CONTRACTOR REPORT

SAND80-7017/1 of 2 Unlimited Release UC-63a

Analysis and Design of • Residential Load Centers

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Final Report

Volume 1. Technical Volume

General Electric Energy Systems and Technology Division King of Prussia, PA 19406

Prepared by Sandia National Laboratories Albuquerque, New Mexico 87185 and Livermore, California 94550 for the United States Department of Energy under Contract DE-AC04-76DP00789

Printed March 1982

Issued by Sandia National Laboratories, operated for the United States Department of Energy by Sandia Corporation. NOTICE: This report was prepared as an account of work sponsoted by an agency of the United States Government. Neither the United States Govern­ment nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty. express or implied, or assumes any legal liability or responsibility for the accurac}. completeness, or usefulness of any information, apparatus, product, or pro­cess disclosed. or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof or any of their contractors or subcontractors. The views and opinions expressed herein do not necessarily state or reflect those of the United States Government, any agency thereof or any of their contractors or subcontractors.

Printed in the United States of America Available from National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161

NTIS price codes Printed copy: A12 Microfiche copy: AOi

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SAND80-70l7/l of 2 Unlimited Distribution

Printed March 1982

ANALYSIS AND DESIGN OF RESIDENTIAL LOAD CENTERS

FINAL REPORT VOLUME 1. TECHNICAL VOLUME

Distribution Category UC-63a

E. M. Mehalick, R. Landes, G. O'Brien, G. F. Tully, J. Parker

General Electric Energy systems and Technology Division King of Prussia, PA 19406

ABSTRACT

This report presents the results of a study on Residential Load Centers (RLC) which include photovoltaic arrays for elec­trical power generation. Twelve specific climatic regions across the united States were used. Current and future load centers were classified, and the electrical and space condi­tioning loads were developed. Economic evaluations and cost scenarios are projected for the mid-1980's. The five load center types selected for this study are single family detached homes, townhouses, garden apartments, housing for the elderly, and mobile homes. The study concludes that (1) Limited land availability and cost dictate roof mounted arrays for RLC's; (2) Condominium type ownership of the array seems most viable; (3) RLC with buildings of more than three stories complicates the architecture; (4) Systems without batteries are preferred; and (5) Combined PV/thermal collector systems must show improved performance to be com­petitive with separate PV and thermal systems for residential load centers.

Prepared for Sandia National Laboratories under Contract #13-2283 .

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FOREWORD

This report presents the results of a study on the Analysis and Conceptual Design of Residential Load Centers. The program was performed for Sandia Laboratories,

Contract Number 13-2283, under the guidance of C. Rogers.

The study was conducted by the Advanced Energy Programs Department of the General Electric Company, Energy Systems and Technology Division. M. Mehalick served as Program Manager during the program. The program was supported by several subcon­

tractors including Massdesign, Architects and Planners, Inc. of Cambridge, Massachusetts, responsible for all building designs, site layouts and building construction data; R. D. Woodson of the University of Florida, Center for Government Responsibility,

who reviewed the legal and institutional issues related to PV residential load centers;

and General Electric Corporate Consulting Services, which provided the background market and inventory details of current residential load centers. The report was

prepared with contributions from the following individuals: R. Landes, G. O'Brien,

J. Parker, G. F. Tully of Massdesign, Architects and Planners, Inc., R. D. Woodson of the University of Florida, Center for Government Responsibility, and C. Durgin of

General Electric's Corporate Consulting Services.

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TABLE OF CONTENTS

SECTION 1 - INTRODUCTION .

Background .. Report Format Results Conclusions

SECTION 2 - STUDY APPROACH

Summary Requirements and Constraints

Regionalization ... . Weather Data .... . Residential load Center Characterization RlC Building Characteristics Loads . . . . . . . . Photovoltaic Systems Solar Thermal Systems Economics

Study Plan ....

Task 1: Cl assification of Resident; al Load Center Types and Determination of Loads

Task 2: Definition of System Configurations Task 3: Subsystem Tradeoffs and Final Ranking Task 4: Conceptual Designs ...

SECTION 3 - RESIDENTIAL LOAD CENTER CLASSIFICATION

Summary

Single F ami ly Mult i -F ami ly Mobile Home. Housing for the Nurs ing Homes Dormitories .

Selection Criteria

. . Elderly

SECTION 4 - Residential Load Center Building Designs

Summary . . . . . . . . Architectural Guidelines for Designs

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1-1

1-1 1-2 1-2 1-3

2-1

2-1 2-1

2-1 2-1 2-1 2-1 2-1 2-1 2-3 2-3

2-3

2-3 2-3 2-3 2-3

3-1

3-1

3-1 3-2 3-2 3-2 3-3 3-3

3-7

4-1

4-1 4-1

TABLE OF CONTENTS (Cant.)

Northern Single Family Detached, Northern Row House, Southern House Detached . . . 4-1

Southern Multiplex . . . . . . . . . . 4-3 Multi-Family Low Rise Garden Apartments 4-4 Housing for the Elderly 4-4 Mobile Home. . 4-4

Site Characteristics Description of Building Designs

Single Family Detached - Northern House Single Family Attached - Southern House Garages . . . . . . . . . . . . . Single Family Attached - Northern Row House Single Family Attached - Southern Multiplex Multi-Family - Low Rise Garden Apartments Housing for the Elderly ....... . Mobile Homes - Single Width Unit

Description of Energy Conservation Features

Sin9le Fami ly Detached Homes (Northern and Southern) ............ .

Northern Row House, Southern Multiplex, and Multi-Family Garden Apartment

Housing for the Elderly Mobile Homes

4-5 4-7

4-7 4-12 4-12 4-17 4-21 4-28 4-28 4-39

4-39

4-39

4-42 4-44 4-46

References . . . 4-47

SECTION 5 - RESIDENTIAL LOAD CENTER ELECTRICAL LOAD DEFINITION 5-1

Summary 5-1 Electrical Loads 5-5

Single Family Detached House 5-5

,Baseload ....... . Domestic Hot Water .. . Cooking and Clothes Drying Total Electrical Load

Single Family Attached House Apartment . Mobile Home ........ .

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5-5 5-9 5-9 5-16

5-18 5-18 5-20

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TABLE OF CONTENTS (Cont.)

Housing for the Elderly ........ . 5-22

Baseload, Cooking and Clothes Drying 5-22 Elevator . . . . . . 5-23 Domestic Hot Water. 5-23

Projections for Years 1986 and 2000 5-27

Baseload Projections 5-27 Cooking, Clothes Drying and Domestic Hot Water

Projections . . . . . . . . . . .. 5-29 Summary of Electrical Demand Projections for

1986 and 2000 5-29

References . . . . . . .

SECTION 6 - SPACE CONDITIONING LOADS

Summary . . . . . . . . Analytical Technique .. Building Characteristics and Modeling

SECTION 7 - UTILITY PRACTICE FOR RESIDENTIAL SERVICE

Summary . . . . . • . . . . . . . . . . Residential Service ......... .

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6-1

6-1 6-2 6-8

7 -1

7-1 7-7

Overhead and Underground Distribution Service 7-7

Overhead System Underground System .

7-7 7-8

Distribution Transformers and Service Cabling 7-8

Distribution Transformers 7-8 Service Cabling ... . . 7-14 Transformer and Service Cabling Costs 7-17

Utility Practices for Specific Housing Types 7-17

Single Family Detached ... . . . 7-17 Single Family Attached (Townhouse) 7-19 Garden Apartment Building. . . . . 7-19 Mobile Home. . . . . . . . . 7-19 Housing for Elderly - Mid Rise Apartment

Building 7-19

References . . . 7 -21

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TABLE OF CONTENTS (Cont.)

SECTION 8 - PHOTOVOLTAIC/THERMAL SYSTEM DEFINITION

Summary . . . . . . System Definitions.

Solar Array .. Power Conversion Storage . . . . . Space Conditioning Equipment

System Configurations

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8-1 8-1

8-1 8-4 8-4 8-4

8-4

PV-Only Systems . 8-5

Configuration I(a) - PV-Only, Battery Direct Charge, All-Electric Load. 8-5

Configuration I(b) - PV-Only, No Storage, Sellback . . . . . . . . . .. 8-5

Configuration I(c) - PV-Only, No Storage, Fossil Heating, Vapor Compression Cooling. . .. .......... 8-5

Configuration I(d) - PV-Only, No Storage, Sellback . . . . 8-5

Side-By-Side PV and Thermal Systems . 8-5

Configuration II(a) - Side-by-Side, All-Electric, Solar Supplemented .... 8-5

Configuration II(b) - Side-by-Side, All-Electric, Solar Driven Cooling 8-8

Configuration II(c) - Side-by-Side, Elec-tric/Fossil, Solar Driven. . . . .. 8-8

Configuration II(d) - Side-by-Side, Domes-tic Hot Water Solar System 8-8

Combined PV/Thermal System

'Configuration III{a) - Combined PV/T System, All Electric

References . . . . . . .

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8-9

8-10

SECTION 9 - PERFORMANCE AND ECONOMIC ANALYSIS METHODOLOGY 9-1

Summary . . . . . . . . . . .. .. 9-1 Performance Analysis Methodology . . . . . . . 9-1

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TABLE OF CONTENTS (Cont.)

PV Systems

Solar Array Electrical Model Battery Model Inverter Mode 1

Thermal Systems . .

Vacuum Tube Solary Collector Combined Solar Thermal Collector

Economic Analysis Methodology

RLC Ownership and Assumptions Energy Price Assumptions Economic Model ....

Levelized Annual Cost Levelized Annual Benefits

References .

SECTION 10 - ECONOMIC AND PERFORMANCE ANALYSIS

Summary . . . . . . . Single Family Detached

Conceptual Design Cost Estimates . Performance Results

PV-Only System with Feedback ... PV-Only System with Fossil Heating PV-Only System with Battery Storage Side-by-Side PV/Thermal Systems PV-Thermal Solar Hot Water Heating System Combined PV/Thermal Systems

Townhouses, Apartments and Elderly Housing

Conceptual Design Cost Estimates Performance Results

PV System Without Storage .. Side-by-Side PV/Thermal Systems PV/Thermal Hot Water Heating System Load Sensitivity Studies ..... .

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9-1

9-1 9-3 9-3

9-3

9-4 9-4

9-4

9-4 9-12 9-12

9-12 9-15

9-16

10-1

10-1 10-6

10-6 10-7 10-12

10-12 10-15 10-19 10-27 10-32 10-41

10-41

10-41 10-46 10-49

10-51 10-51 10-51 10-58

TABLE OF CONTENTS (Cant.)

Mobile Home

Conceptual Design Cost Est imates Performance Results

SECTION 11 RLC LEGAL/INSTITUTIONAL ISSUES

SECTION 12 - BUILDING CODE REVIEW.

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10-61 10-65 10-67

11-1

12-1

Summary . . . . . . . 12-1 Building Code Analysis for Residential Load Centers 12-1

Model Code Characteristics . . . . .. 12-1 Code Sections Pertinent to Residential Photo-

voltaic Systems . . . . . . 12-3 The Standard Building Code 12-4 Uniform Building Code. . . . . 12-8 Basic Building Code 1978 (BOCA) 12-12

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LIST OF FIGURES

Figure No .

2-1 Twelve Study Regions Across the U.S ...

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4-13

4-14

4-14a

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4-16

4-17

4-17 a

1976 U.S. Residential Housing Inventory

Single-Family and Multi-Family Construction Trends

Mobile Home Shipments

Selected Southern House Site Layout

Northern Detached House Site Layout

Elevations of Northern House with Roof Mounted PV

Elevations of the Northern House without Roof Mounted PV ..... .

Floor Plan for Northern House

Southern House Elevations

Southern House Floor Plans

Southern Garage Elevations

Northern Garage Elevations

Details of Southern Garage

Details of Northern Garage

Alternate Design for the Northern Garage

Northern Rowhouse Perspective

Northern Rowhouse Site Plan

Northern Townhouse Elevations

Southern Multiplex Perspective

Southern Multiplex Elevations

Southern Multiplex Floor Plan

Southern Multiplex

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Page

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4-13

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4-27

4-29

LIST OF FIGURES (Cont.)

Figure No.

4-18 Garden Apartments Perspective

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4-23

4-24

4-24a

4-25

4-26

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4-28

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5-4

5-5

Garden Apartments Floor Plan

Garden Apartments Elevations and Sections

Garden Apartments Site Plan

Housing for the Elderly Perspective

Section Elevation of the Housing for the Elderly Design ..

Housing for the Elderly Floor Plan

Unit Floor Plans and Site Layout for Housing for the Elderly . .

Mobile Home Elevations and Plans

Mobile Home Site Plan

Mobile Home Energy Conservation Features

Elderly Housing Energy Conservation Details

Single Family Home Diversified Land Profiles

Seasonal Characteristics of Baseload Electrical Demand Profiles. • . .. . ...... .

Domestic Hot Water Electrical Load Profiles for Single Family Homes (4940 kWh/Year) .

Approximate Temperature of Water from Nonthermal Wells at Depths of 30 to 60 feet (Ref. 5-6)

Electrical Load Profiles Cooling and Clothes Drying

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4-45

5-7

5-8

5-11

5-12

Single Family House ... .. 5-15

5-6 Average Daily Diversified Electrical Load Profile (Excluding Space Heating and Cool ing). 5-17

5-7 Retirement Home Electrical Use for a Typical Opera-

5-8

ting Day. . ... 5-24

Electrical Load Profiles Per 1000 Sq. Ft. - 1977 Base Year Housing for the Elderly (Base load, Cooking and Clothes Drying) (Incl. Congregant Facilities) . . . . . .. .

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LI ST OF FIGURES

Figure No.

10-14 Economic Tradeoffs for the All-Electric System with Battery Storage for the SFD RLC in Boston . 10-30

10-15 Performance Summary of Side-by-Side PV?Thermal Systems for Single Family Detached Homes 10-31

10-16 Comparison of Economic Tradeoffs for SFD RLC Side-by-Side Systems in Boxton . 10-33

10-17 Comparison of Economic Tradeoffs for SFD RLC Side-by-Side Systems in Phoenix . . 10-34

10-18 Economic Tradeoffs for SFD RLC Side-by-Side Rankine System •• •... 10-35

10-19 Economic Tradeoffs for SFD Side-by-Side Fossil Heating, DHW, and Absorption A/C System. . 10-36

10-20 Summary of Economic Performance for Side-by-Side PV/

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10-22

10-23

10-24

10-25

10-26

Thermal Domestic Hot Water System for Single Family Detached Houses •••••••••.. 10-42

Combined PV/Thermal Collector System Performance Summary for SFD Houses . ...

Economic Tradeoffs for SFD(s) RLC Combined Collector for All-Electric System ..

Multi-Family Heating and Cooling System Distribution ...•••.•.••.

Monthly Performance of PV Only System Without Storage for Single Family Attached ....

Monthly Performance of PV Only System Without Storage for Garden Apartments (396 m2) ..

Monthly Performance of PV Only System Without Storage for Home for the Elderly (1887 m2)

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10-54

10-27 Summary of Cost to Benefit Ratio for Residential Load Centers . ... . . . . . . 10-56

10-28 Summary of Economic Performance for Side-by-Side PV/ Thermal Domestic Hot Water System on Garden Apartments .. 10-59

10-29 Site Layout for a Mobile Home Park 10-62

10-30 Mobile Home Park Design Layout Concept 10-63

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LIST OF FIGURES

Figure No. • 10-31 Economic Results for Mobile Home Feedback

Sys tern .'. . . . . . .. ..... 10-69

10-32 Economic Tradeoffs for the Grid Connected Mobile Home Park System with Battery Storage in Phoenix 10-70

10-33 Economic Tradeoffs for the Stand Alone Mobile Home Park System in Phoenix • . . . • • . . . . 10-71

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Tab 1 e No.

3-1

3-2

3-3

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5-1

LIST OF TABLES

Classification of Residential Housing Types

Housing Models for Study

Key Characteristics of Selected Housing Models

Summary of Building Characteristics ..

Summary of Average Annual Electrical Energy Consumption

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3-3

3-9

4-2

By Residential Housing Type 5-2

5-2 Seasonal and Regional Effects on Loa8 Definition 5-3

5-3 Summary of Electrical Demand Projections for 1986 and 2000 . . . • • . • . . . • • . • . . 5-4

5-4 Domestic Hot Water Seasonal Correction Factor for Baseline Profile. . .. ....... 5-10

5-5 Regional Correction Factors for Domestic Hot Water

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5-7

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5-12

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6-2

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Use . . . • • • • . . . . . . 5-13

Annual Residential Use of Electricity for Cooking

Single Family Home Electrical Demands - 1977 Base Year . . . • . .• ....

Apartment Annual Electrical Energy Demands (Baseload, Cooking, Clother Drying and Domestic Hot Water).

Garden Apartment Energy Demand Adjustment Factors -1977 Base Year . . . . . . . • . . . . • . .

Mobile Home Annual Electrical Energy Demands -- 1977 Base Year .•...............

Mobile Home Energy Demand Adjustment Factors -1977 Base Year . . . . . . . . . . .

Baseload Electrical Demand Projections

Building Temperature Control Assumptions

Occupancy Schedules for Each RLC

TMY Heating and Cooling Degree-Days for the Study Site s . • . . . . . • . .

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5-14

5-16

5-19

5-20

5-21

5-22

5-30

6-9

6-9

6-11

Table No.

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6-5

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6-7

6-8

6-9

6-10

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6-12

6-13

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7-3

7-4

7-5

7-6

8-1

8-2

LIST OF TABLES

Sunbelt Single Family Monthly Load Profiles

Northern Detached Single Family Monthly Load Profiles . . .

Northern 4 Unit Townhouse Monthly Load Profiles

Southern 4 Unit Multiplex Monthly Load Profiles

Northern 8 Unit Garden Apartment Monthly Load Profi les. . •.•...•.

Sunbelt 8 Unit Garden Apartment Monthly Load Profi les . . .

Northern Mobile Home Monthly Load Profiles

Sunbelt Mobile Home Monthly Load Profiles

Northern Housing for the Elderly Monthly Load Profiles. . • • • .. ..

Sunbelt Housing for the Elderly Monthly Load Profi les . . . . . . . . .. . .....

Utility Electrical Service Practices Related to Specific Housing Types

Standard Transformers • • • . . . . . . . . . •

Typical Primary Feeder Three Phase Distribution Voltage ..••••....

Standard Service Line Voltages

Demand Factors and Watts per Mobile Home Site (Minimum) for Feeders and Service-Entrance Conductors . • . . . . . . . . . . .

Typical Distribution Transformer and Service Cable Costs .••... . .•

Summary of Selected System Configurations

Subsystem Definitions ..•. . ...

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7 -3

7-11

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Tab le No.

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9-2

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9-4

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10-2a

10-2b

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10-10

10-lIa

10-llb

lO-11c

10-12

LIST OF TABLES

RLC Ownership Operating Scenarios

Economic Assumptions for Different Ownership

RLC Ownership Advantages and Disadvantages

Summary of Energy Prices

Relative Ranking of Residential System Performance and Economics Through Cost-to-Benefit Ratio for Single Family Detached Houses

Concept Ranking Economic Assumptions

Summary of System Cost Estimates for RLC Types

Summary of Cabling Requirements for SFD House Layouts ....... . .... .

Cost Estimates for Module Installation

Electrical Component Cost Estimates in 1980$

Summary of System Costs for SFD-RLC

Battery System Additional Fixed Costs

PV-Only Systems Performance System for All-Electric Loads with Feedback ............ .

System Performance Comparisons for Single Family Detached Homes. .......... .

Summary Performance of PV System with Battery Storage for the SFD-RLC. .

PV/Thermal Side-by-Side Systems Performance SYSTEM II(a): PARALLEL HEAT PUMP SYSTEM

PV/Thermal Side-by-Side Systems Performance SYSTEM II(b): FOSSIL HEATING/ABSORPTION COOLING

PV/Thermal Side-by-Side Systems Performance SYSTEM II(c): RANKINE DRIVEN HEAT PUMP

Summary of Performance Results for PV/T SOLAR DHW SYSTEMS IN SFD RESIDENCES

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9-8

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9-13

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Table No.

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LIST OF TABLES

Combined PV/Thermal Systems Performance SYSTEM III(a): PARALLEL HEAT PUMP SYSTEM

Summary of Peak System Output for Available Roof Are a . • . • • • • . • . . . . . . • . .

Residential Load Center - Block IV PV Single Modules . . . . . . .

Electrical Equipment Cost Estimates

Summary of System Cost Estimates ..

Summary of System Performance for Different RLC's -

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10-50

All Electric System Without Storage 10-55

PV/Thermal Side-by-Side Systems Performance for Garden Apartments . .......•. . 10-57

Summary of Performance Results for PV/T Solar DHW Systems in Garden Apartments II(d) 10-58

Summary of Load Profile Variation Effects on Performance . . • • . . . . . . • . • . . 10-60

10-22 Build-Up of the Array Field and Field Characteristics 10-64

10-23 Cost Estimates for 50-Unit Mobile Home Part Photovoltaic System. ....... 10-66

10-24 PV-Only Systems Performance System for All-Electric Loads with Feedback for the Mobile Home RLC . 10-67

10-25 Summary Performance of PV System with Battery Storage for the Mobile Home RLC . " .•..... 10-68

11-1 Outline of Legal/Institutional Issued for Residential Load Center Photovoltaic Systems .. 11-2

11-1 Outline of Legal/Institutional Issued for Residential Load Center Photovoltaic Systems ..•.. .• 11-3

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SECTION 1 INTRODUCTION

Background

This report presents the results of a study on Residential Load Center (RLC) solar energy systems which include photovoltaic (PV) solar arrays for electrical power generation. General Electri c Company /'Advanced Energy Programs Department conducted the study for Sandia Laboratories with C. Rogers providing program direction and guidance.

The objective of the program is to evaluate the application of solar PVand solar thermal systems to residential load centers in twelve specific regions across the United States. Current and future residential load centers are classified and elec­trical and space conditioning loads are developed for each of the RLC types. The tech­nical and economic evaluations consider RLC designs and cost scenarios projected for the mid-1980's. The analyses consider regional differences in climatic conditions and in' conventional energy costs to identify where PV and thermal systems may be most attrac­tive. Conceptual designs for selected load center types and regions of the country are presented.

Residential load centers potentially offer several advantages when considering the implementation of solar systems. First of all, implementing larger size systems may provide economics of scale benefits for the balance of system equipment. A higher en­ergy utilization may also be possible. An increased number of users may result in more energy being used directly to meet the load demands and less energy being fed back to the utility. Final1y,RLC's may minimize the retrofit barrier, especially if the sys­tems are ground-mounted.

On the other hand, RLC's potentially offer several 'disadvantages. Ownership becomes a significant problem area, especially in single family detached units. A con-

'dominium type arrangement is conceivable, but each user/owner must also be assured equal benefit from the system. The attractiveness of these systems must be accepted by build­er/developer sin'ce they will be the ultimate implementer. There must be an advantage to the builder/developer in building solar developments, especially if they do not retain ownership. Finally, land availability is a serious problem area. The reason for cluster developments is to increase the density of living units per unit area due to the high

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cost of the land. The land has more value to the developer for building additional units than to construct an energy system for the tenants.

These advantages and disadvantages are basically non-technical issues, but can seriously affect the implementation of these systems.

Report Format

Sections of the report are ~evoted. to different topic areas. Section 2 provides a synopsis of ~he approach to the study program. Section 3 discusses the classification of the RLC's. A great deal of data is available on the different RLC types, housi.ng inventories, and trends for RLC's. The results presented in Section 3 are supplemented with more detail in Appendix A. Section 4 provides the new construction, energy con­servative architectural designs of all the selected RLC types along with building draw­ings (perspectives, elevations, floor plans, and site plans). This section is supple­mented with Appendix B which provides additional detail in site layouts for single fami­ly detached home RLC types. Sections 5 and 6 discuss the loads for the selected RLC types--both electrica.l. loads (Section 5) and space conditioning loads (Section 6).

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Section 7 is devoted to discussing general utility practices for servicing resi- • dential load center types of installations. A study of current practices is discussed with several tables of data. Section 8 discusses the basic solar system configurations analyzed in the study. Sections 9 and 10 discuss the approach, assumptions, and results to the performance and economic analyses.

An outline nf a review of RLC legal and institutional issues is presented in Section 11. A complete summary report to the outJine is included in Appendix C. Final­ly, Section 12 addresses some of the building codes potentially affected by the PV/ building interface.

Results

The five·load centers selected for .study include single family detached homes, townhouses, garden apartment~, housing for the elderly and mobile homes. Several owner­ship arrangements are considered, but the cond·ominium type arrangement shows the best potential for ownership. The ownership issue, relevant to providing equal benefits from

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the PV system, is a disadvantage of the load center concept. Land area available for siting large collector arrays is another key concern for load centers. The reasons for

townhouses, mobile home and apartment type residential housing is usually for higher unit density due to the lack of and cost of available land area. This factor leads to

roof-mounted arrays as in single family homes. The dc power distribution losses from dispersed roof-mounted arrays tend to preclude centralized power conversion units for a

group of load center building types. The conceptual designs developed therefore con­sider power conversion equipment located in each building type.

To roof mount the PV arrays for single family detached houses (in the RLC con­

cept), a centralized garage is used. Garden apartments, rowhouses, and multiplex multi­family units can be designed to provide large south facing roof areas. Mid-rise build­

ings, as typical for Housing for the Elderly, became more complicated with limited roof area availability. Mobile home units require a centralized, ground mounted array.

The performance and economic analyses indicate similar results to the single

family detached houses from previous studies. The most attractive regions are the Southwest, Northeast, and Southeast, regions of high insolation or high energy costs.

The PV-only system shows the best economic viability in all regions with sellback rates of 50% or greater. Specific conclusions from the study are listed in the following

section.

Conclusions

The study has led to the following principal conclusions:

• Similar to residential single family detached study results, most sites studied show economic viability of PV systems in the 1986 time frame at

70¢/peak watt array costs with the economic assumptions used in the study.

• Limited land availability and land costs in high density family housing areas 1 eads to roof mounted PV arrays for most Res i dent i a 1 Load Center types.

• Condominium type of ownerships of the PV systems is required to provide the homeowner tax advantages for economic viability of the systems .

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• There is no incentive for commercial ownership of the systems for most RLC types. Mobile home parks are possibly the exception; however, the economics

are not as attractive.

• System sizing becomes limited by the amount of available roof area.

• • Including large roof array areas on RLC buildings with more than three stories

complicates the architectural design and the resulting electrical circuit

layout. In addition, only small portions of the total building loads can be ~ serviced.

• Large economies of scale of balance of system equipment are not realized in RLC's when the arrays are roof mounted and service only the loads of that

particular building.

• Equal distribution of the benefits from the solar system to each condo owner can be difficult. Equitable metering is a major problem with residential load

centers. •

• PV-only solar energy systems for residential use should be emphasized since their potential economic viability was as good as or better than other solar energy options evaluated in all regions.

• On the basis of costs and benefits assumed, residential systems without bat­teries are preferred over systems with batteries. Systems without batteries,

however, require that utilities accept excess PV output with sellback rates in the range of 40 to 50 percent of the electricity buy rate.

• Side-by-side PV/thermal systems require approximately equal PV system and thermal system $/m2 costs to show economic viability. PV/thermal domestic hot

water systems show better economic potential due to the year-round thermal

load and thus higher thermal utilizations.

• Combined PV/thermal collector system must show improved performance and costs over those assumed in this study to show economic viability.

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•

•

•

•

SECTION 2 STUDY APPROACH

Summary

This section presents a brief synopsis of the approach taken for the RLC study. The requirements and constraints are discussed initially and then a descrip­tion of the study plan is presented.

Requirements and Constraints

Basic requirements and constraints used in this study are enumerated below.

Regionalization

Analyses are performed for twelve regions, thirteen sites, considered to be representative of various climates within the continental United States (see Figure 2-1).

Weather Data Typical Meteorological Year (TMY) weather tapes for the thirteen sites are

used as the input for the performance analyses.

Residential Load Center Characterization RLC's are selected for the 1983-1986 time frame assuming new construction.

RLC Building Characteristics

Architectural designs for new construction are developed by Massdesign. • Building styles reflect those prevalent in the selected regions. Average size units

are assumed for each building type.

•

Loads

The magnitude and temporal characteristics of the loads are defined in suf­ficient detail to enhance the acceptance and validity of the final results.

Photovoltaic Systems

Conceptual designs are based on current technology regarding solar cell effi­ciencies. Costs reflect those projected for the mid-1980's or those required to achieve overall system economic viability.

2-1

"" , '"

•

X>X> 00 NOT ""N~RALIZ~ IN ~ MOUNTAINOUS AR12AS

o SOlMF;y SITeS

BISMARCK o

Fig,,, 2-J. T."" Sto'" Regi,", A"", the u.s .

• • • •

~ Solar Thermal System~

•

~

Conceptual designs are based on current technology regarding solar collectors

and supporting subsystems. Cost projections to the mid-1980's were used in the eco­nomic evaluations.

Economics

Economic analyses are based on 20-year payback periods with start of opera­

tions assumed to be in 1986. Appropriate projections of electricity and fuel esca­lations are considered. Resident ownership of the solar energy system is assumed in most cases. Commercial and utility ownership are also considered. For those sys­tems involving the sellback of electricity to the local utility, sellback rates are treated parametrically in establishing economic breakeven levels.

Study Plan

The program consists of four primary tasks:

Task 1: Classification of Residential Load Center Types and Determination of Loads

Multi-family dwelling units are categorized and average electrical and ther­mal loads appropriate to them are quantified.

Task 2: Definition of System Configurations The constituents of the solar systems for these residential units are identi­

fied and preliminary ~creening completed.

Task 3: Subsystem Tradeoffs and Final Ranking The performance of the promising systems is analyzed and a final ranking and

... application selection made.

•

Task 4: Conceptual Designs

The physical appearance of the selected dwellings is depicted in architec­

tural drawings and the arrangements of the identified solar energy systems characterized.

The conceptual designs for the building types are formulated during the per­formance analyses to provide the base for the analyses .

2-3

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•

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SECTION 3 RESIDENTIAL LOAD CENTER CLASSIFICATION

Summary

An extensive literature search is conducted to classify residential housing into a set of appropriate categories. Six major categories are identified and hous­ing types within each of these categories defined. The initial list of residential housing types is presented in Table 3-1. Each of these categories is defined below.

Table 3-1 Classification of Residential Housing Types

• Single Family • Single Family Detached

• Single Family Attached • Townhouse (Row House)

• Duplex • Triplex • Fourplex (Quad)

• Patio House

• Mu lt i -Fami ly • Garden Apts. (Low Rise)-l to 3 Stories

• Mid-Rise -4 to 8 Stories

• High-Rise -Over 8 Stories

• Mobile Home • Single Width

• Double Width • Expandable

Single Family

• Housing for the Elderly • Independent Living

(Multi-Family) • Dependent or Congregate Living

(Mu lt i-Family)

• Nursing Homes • Personal Care • Intermediate Care

• Sk i 11 ed Care

• Dormitor i es • Single Family Attached

• Multi-Family

The single family category includes the single family detached house which

sits on its own lot, and a number of different types of attached dwellings. The • most widely known attached dwelling is the townhouse. With its characteristic party

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wall (a wall common to two houses) and linear lineup, townhouses are usually built in a series of five to ten units. Plexes, which encompass the duplex, triplex,

fourplex (or quad), etc. are similar to townhouses, but have many ch~~acteristics of the single family detached dwelling. The plexes are attached in a number of unique

ways, which enhance privacy and the detached look. Another single family attached type dwelling is the patio house. The U-shaped or L-shaped structure encompasses the entire lot, with attachment to the adjoining dwelling at the lot line. Their garden courts are enclosed either by the house or by walls, with rooms bordering the

courts. Thus, both interior and exterior secluded living space is provided. A variation of the patio house is the atrium house which has an open court within the

interior onto which rooms open.

Multi-Family The multi-family category includes the low rise garden apartments and mid and

high rise buildings. Structure height being the distinguishing feature that sepa­rates these apartment buildings into a particular type. Three stories is the maxi­

mum height for the garden apartments, with the mid-rise encompassing buildings from

•

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four to eight stories. •

Mobile Home

Mobile homes are commonly divided in three types, the single wide unit, the double wide unit and the expandable. The predominate single unit types are 3.66 m.

and 4.27 m. wide, with double units made up of two single wides tied together to form a dwelling. In recent years some triple wide units have been built, but these

very large mobiles represent, at this time, a specialized and almost insignificant portion of the mobile home market.

Housing for the Elderly

Housing for the elderly includes two types, independent living facilities and dependent (or congregate) housing. Independent living facilities are primarily pro­

vided in the form of conventional apartment type buildings. Dependent living in­volves provision of congregate facilities including a common dining hall as well as

social and recreational centers and possibly a small infirmary.

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• Nursing Homes Nursing home housing falls into three types, depending on the degree of pro­

fessional medical and nursing care provided. The three types are designated as skilled care, personal care and intermediate care units. The skilled care unit provides varying

levels of health care for ailing long-term aged residents who range from ambulatory and fairly active to completely bed ridden. Medical and full nursing services are available. Intermediate care nursing homes house long-term elderly residents who are

well enough to move about on their own. An infirmary and some nursing care is avail-• able. The personal care unit is primarily residential facilities with some services

and care. It very closely resembles the dependent (congregate) housing for the elderly

•

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•

with additional support in the form of housekeeping and personal health services.

Dormitories Campus housing constructed during the past decade generally resembles conven­

tional housing. Two categories primarily utilized were the single family attached

units such as townhouses and multi-family housing in the form of garden apartment and mid-rise buildings. Inner city colleges and universities have constructed some high­rise residences since land costs are exceedingly high in urban areas.

The selected RLC types from these categories are listed in Table 3-2. The following subsection describe the rationale for the selection.

Table 3-2 Housing Models for Study

• Single Family Detached • Single Family Attached - Townhouse • Multi-Family - Garden Apartment (Low Rise) • Mobile Home - Single Width Unit • Housing for Elderly - Congregate Living -

Mid-Rise Building

Housing Characteristics and Trends

Having classified housing types, characteristics and trends associated with each type are analyzed to permit selection of appropriate 1986 models for the study. The results of this analysis are briefly summarized below. Appendix A discusses in more detail the residential development trends.

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With more and more consumers being priced out of the housing market, developers will be turning to somewhat smaller houses, attached units, and cluster plans. Closer­in, higher density residential developments seems to be the trend in residential housing. Sophisticated design techniques are being applied to maintain the privacy, individuality, and other advantages of the low-density housing that predominated during the 1946 to 1975 period.

Land development has changed. The single lot is no longer the typical unit of growth. Instead, residential subdivision is now the basis of land development.

Setting, landscaping, and surrounding uses of land are of prime concern. Residen­tial housing is being arranged in closely related groups, defined as clusters, in­stead of spreading houses uniformly over a tract. To reduce installation and total

land costs, structures are placed on appropriate terrain at higher densities, pre­serving, to the greatest extent possible, surrounding natural features.

Single family detached homes, though exhibiting a rather level rate of con­struction in the 1970's, continue to dominate the residential market, representing

•

•

68% of the total U.S. inventory (Figure 3-1). The housing consumer still continues • to make the single family detached home his first choice. Single family attached homes (i.e., townhouses) are the fastest growing segment in the housing market though 1976 census data indicates that this category represents only 4% of total inventory. Industry projections indicate the attached homes will steadily increase their share of the single family market.

Multi-family dwelling units, which account for 28% of the inventory, have, since the early 1970's, been losing market share to the single family home (Figure

3-2). Industry projections indicate this trend will continue. In the multi-family category, low-rise buildings (i.e., garden apartments) are the predominant type

being constructed. Since 1973, approximately 99% of multi-family buildings con­structed were in the one to three story class. The average floor area per apartment continues to decrease.

• Mobile home shipments, after a phenomenal growth period during the 1960's and

early 1970's (Figure 3-3), tumbled during the 1973-1975 recession period. Shipments in the latter half of the 1970's indicated a resurgence in demand for mobile homes,

probably accounted for by the current explosion in cost for conventional single ~

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Number of Dwell ing Units Percent (%) Of • Category (Thousands) Total Inventory

Single Fami ly Detached 50,475 63.6 Single Family Attached 3,136 4.0 Multi-Family 22,078* 27.8 Mobile Home or Tr a il er 3,627 4.6

Total Inventory 79,316

, * to 4 units - 10,175 • 2 5 units or more - 11,883

, ONE FAMILY DETACHED UNIT 63.6%

• HOMES, TRAILER 4.6%

ONE FAMILY ATTACHED UNIT 4.0%

• Figure 3-1. 1976 U.S. Residential Housing Inventory

• 3-5

100

90

" 80 • 0 ...., Single-Fami ly u

" 70 ... ...., V>

'" 0 60 u

-.;; ...., 50 0

>-~ 0

40 ..., " <1J U

30 ... Multi-Family OJ

Q.

20

10 • 1964 65 66 67 68 69 70 71 72 73 74 75 76

Year

Figure 3-2. Single-Family and Multi-Family Construction Trends

600000

550000 • 500000

450000

-0 OJ

400000 Q. Q.

.<= Vl

'" 350000 OJ E 0 :J:

~ 300000 .c 0 :E 250000 • 200000

150000

100000

50000 "II., 9'""5-=-9 --;"19""6""1--;-19~6:-:;3-""'-;19~675 --'1;;;976 7:;--'1;;;9:;;-69;;-'1"*9 77'i1"1c;9 77'3"1;;-:9 7"'5-'1t9 7777-1,19 7 9

Year

Figure 3-3. Mobile Home Shipments • 3-6

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family homes. Though representing somewhat less than 5% of the total U.S. housing inventory, mobile homes, nevertheless, rose significantly from only 2.3% in 1970. At the end of 1978 there were approximately 4.2 million mobile homes in the U.S.

Housing for the elderly is another residential housing type that has gained prominence in the 1970's and promises to continue to gain in importance in the fut­

ure. Our elderly population, 65 years and over from 1950 to 1976 while the U.S. total population has grown. The predominant housing types constructed for the el­

derly are mid and high-rise apartment buildings.

Selection Criteria

The criteria used in selecting housing types as models in the study include:

(1) Housing types that represent a significant number of units in the U.S. housing inventory and indicate maintenance or improvement of that posi­

tion well into the 1980's.

(2) Types that are rapidly increasing their market share and will represent a significant portion of new residential housing starts in the next de­cade.

(3) Types that are readily grouped or already form a potentially viable re­sidential electrical load center.

Based on this criteria, five residential housing types are selected for study

(Table 3-2). The nursing home and dormitory categories are eliminated for the fol­

lowing reasons. Nursing homes of the skilled and intermediate care type are specialized institutional facilities numbering less than 20,000 in the U.S. Personal care nursing homes are similar to congregate living - housing for the elderly which has been se­

lected for study. With the decreasing birth rate in the U.S., college enrollement

rates are projected to continue their decline well into the next decade, which would indicate little possibility of a resurgence in on-campus residential construction in

the future. Campus residential housing facilities, built in the late 1960's and

early 1970's predominantly represent conventional housing of the single family attached, garden and mid-rise apartment types which have been selected for study.

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Models are defined for each residential housing category selected, based on a composite of characteristics typical of hbusing built since mid 1960, as well as pro­jected characteristics of buildings to be constructed in the 1980's. A summary of

key characteristics of the selected housing models is provided in Table 3-3.

• The results of the screening process indicated high rise apartments as a poor

application for solar systems. Selecting the housing for the elderly as a mid-rise building type is a comprise to address the issue of solar systems for this building type. •

Residential load centers of the types classified are normally located in areas

of limited land area availability. In most of the cases, roof mounted arrays are con­

sidered. The mobile home park, where the units in many cases are mobile and there is available land area, ground mounted arrays are possible. The housing type designs discussed in the next section consider these characteristics.

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W I ~

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SINGLE FAMILY DETACHED

SINGLE FMlILY ATTACHED

tlUL TJ- FAr4I LY

tlOBILE HOME

_.

HOUSING FOR ELDERLY -CONGREGATE LIVING

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_.-NO. OF OCCUPANTS

4

4

I 3

I 3

I I

120-180

I ,

• • • Table 3-3

Key Cilaracteristics of Selected Housing Models

KEY CHARACTERISTICS --- ---

APPROX. DEVELOPNENTI TYPE OF NO. OF NO. OF NO. OF APPROX. TYPE OF r4AJOR STRUCTURE ROOf'lS BEDROOflS BATHROOMS FLOOR SPACE GARAGE APPLIANCES DENSITY

( FT2) IN DlV. (DIV./ACRE) 2 STORY-N ATTACHED 1 STORY-S 6 3 2 1600 OR ALL 4-6

(OPTIONAL DETACHED DEN)

2 STORY ATTACHED TmmHOUSE 6 3 2 1600 GARAGE ALL 8-10

(OPTI~~AL DEN

2-3 STORY GARAGE! GARDEN 4 2 1 900 CARPORT ALL 12-16

~mb~~~T DETACHED

SINGLE WIDTH 4 2 1 980 - ALL 6-8 14 FT x (OPTI~~AL 70 FT DEN

4-5 STORY 100-150 80%-1 BED I/APT. 700 CENTRAL MID-RISE PLUS 10%- 1 BED/, 750 '- UTI L1TY .-ELEVATOR(S CONGRE- 10%-2 BED 900 ROOM

GATE CONGREGATE (WASHERS/ DINING, 50-100/APT. DRYERS) SOCIAL & RECREA-TJONAL - -

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SECTION 4 RESIDENTIAL LOAD CENTER BUILDING DESIGNS

Summary

Building and plot designs are developed for the five study building types se­lected in Section 3, Residential Load Center Classification Massdesign Architects and Planners, developed the building designs with Northern and Southern designs within an RLC type where appropriate. A listing of the specific building types follows:

• Single Family Detached - Northern House - Southern House

• Single Family Attached - Northern Row House

• - Southern Multiplex

•

•

• Multi~Family -- Low Rise Garden Apartment • Housing for Elderly -- Mid-Rise Building • Mobil~ Home -- Single Width Unit

Table 4-1 summarizes the building characteristics for each of the designs.

Architectural Guidelines for Designs

The architectural designs for the various categories of residential buildings included energy conservation and passive solar features appropriate for 1986. Speci­fic requirements for each design are discussed in the following sections.

Northern Single Family Detached, Northern Row House, Southern House Detached These three residences, in general, share the following requirements: • 1500 to 1700 square feet of floor plan area which includes three bedrooms,

two full baths, living room, dining area, eat-in kitchen, and equipment room.

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'"

Table 4-1 Summary of Building Characteristics

RESIDENTIAL LOAD TOTAL TOTAL NO. UNIT ROOF ROOF LOT SITE FLOOR ROOF AREA AREA AREA

CONSTRUCTION ENERGY CENTER TYPE OF FLOOR SLOPE CONSERVATION AREA AREA AREA /UNIT fUNIT fUNIT

FT2 FT2 UNITS FT2 FT2 FT2 FT2

NORTHERN HOUSE 16440 9930 10 3BR 1644 993 40· 6000 7500 Wood frame; slab R-19 wa Is; R-30 clg PV ON ROOF +504 on grade: wood wind 2 & 3 gLazing: very

Garag ) frms; gyp bd inter tight; i.nsulated sla --

NORTHERN HOUSE 17310 10000 10 3BR 1731 1000 40· 6000 9083 Same as Northern House with PV on Roof PV SEPARATE 8250)* I

I SOUTHERN HOUSE 15070 10000 10 3BR 1507 1000 28· 6000 8845 Same as Northern Houses PV SEPARATE I NORTHERN 9984 5958 6 3BR 1664 993 40· 4000+ 6000+

! . Same as Northern Detached Houses

ROWHOUSE

SOllTIIERN 6298 3554 4 3BR 1606 889 28° NA 7000+ Same as Northern, Same as Northern MULTIPLEX (part shade) 1543 but with fireproof

3000 I 750 gypsum part Ins • (min. shade) where req'd.

GARDEN 11280 7236** 12 2BR 920 603** 35· NA 2500+ Same as Southern Multiplex APARTMENTS (bldg) 960

I 2064 172 (gar.)

_I __ ~-

HOUSING FOR THE 137932 27980 61 lBR 640 182 28° NA 900+ PC conc plank; c( i » II urethane in ext. ELDERLY 80 IBR 588 ment bearing wallb, walls; 3" urethane

13 2BR PC conc balconies; on roof deck: 2 ble blk & brk curtain glazing; structure wall; bIt-up roof; entirely inside in--PV on stl frames sulation; thermal w/metal shrouds b ,-,·ak window frames

.. _--. MOBILE HOME 105840 70000 108 980 M8 35· ~OOO±. 7450 Wood stud and jsts; R-ll walls; R-19

3 BR wd. truss roof; sht roof and floor; metal siding/roof; 2 ble glass; moder-stl bm supports:ply ate infiltration & gyp bd into fin. control.

- _ .. _. _ .. _. --* Minimum possible eite plan (unacceptable designr-**r.his area usee both upper and lower roofe; omits upper, partly Bhaded area of lower roof •

• • • • •

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A plan which allows north or south entry without major layout changes.

Maximum amount of passive solar gain from the south, contingent on a large

roof area.

In addition to the above basic requirements, certain elements vary for the different house styles:

• On the northern and southern detached house, the array is mounted on a de­tached garage or garage complex. Mounting collectors on the roofs of the

detached houses was initially considered but eventually rejected because

of associated PV system distribution losses. This is discussed in Section 10 in more detail.

• On the northern row house the array is mounted on the roof which slopes at a 400 tilt to insure snow shedding.

• An equipment room to house the balance of system equipment .

• Northern houses are designed in a more compact form. This responds to a need for longer, narrower lots running north-south to permit increased solar gain in the northern latitudes where sun angles are lower in the

winter months. It also responds to a stylistic preference of two-story

houses in the northern tier.

• A basement option for northern houses.

~ Southern Multiplex

•

This type of dwelling clusters four three-bedroom units together with a single garage for each unit. Detailed requirements for these units are grossly the same as those for detached houses:

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Three bedrooms, two full baths, living room with dining area, kitchen,

generous storage area.

A central equipment room for the clustered PV array. A private yard for each unit.

• Construction similar to the detached houses, with appropriate adjacent walls.

• Slab-on-grade construction. • Roof Pitch, consistent with southern designs, 280 from the horizontal.

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• PV array area target of 70 square meters per unit.

Multi-Family Low Rise Garden Apartments In this category of the "entry walk-up" type, four units are clustered around

a single entrance, sharing a single staircase. • Unit floor area of 900-1000 ft2.

• Living room, dining area, small kitchen, two bedrooms, and a single bath.

• Elevated unit to be provided with a balcony or roof deck.

• Within the limits of the roof mounted PV array, passive solar gain to be maximized.

• On the upper floor, which is under the roof and likely to receive an ex-cess of summertime solar gain, clerestories are provided to encourage thermo­syphoning ventilation in the summertime when the air-conditioning is not needed.

• PV array target area of 70 square meters per unit, with as much as possible on the building and the remainder on the clustered garages.

Housing for the Elderly In this de~ign the guidelines are much freer. State-of-the-art one and two

bedroom elderly housing units are to be clustered in a building which maximizes the amount of roof mounted PV array.

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• Construction appropriate for the height of the building and for its layout, but definitely non-combustible, with two to three hour fire-resistive con- ~ struction.

• No target PV roof area goal, except the maximization of the area.

Mobile Home

A standard single-wide (14' x 70') mobile home is specified. After investi­gating mobile home construction techniques, it was decided that PV cells should not be roof mounted. The only basic changes to the standard single-wide unit was an in- • crease .in energy conservation level to approximate that expected by 1986.

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Site Characteristics

The site layouts for roof mounted solar arrays on RLC's present many design limitations and problem areas. These limitations are even more severe for single family detached homes. Several site layout schemes, considering individual house mounted arrays, ground mounted arrays and garage mounted arrays, are developed.

The site designs are generated based upon a group of single-family homes, each on a 60 x 100 foot lot, having separate detached garages and lots fed by a cul­de-sac. Each of these designs are evaluated against the following criteria to select the appropriate baseline for this study.

o Total land area per unit required for the entire site plan. o Amount and cost of additional roadway required (if any). o Extent of shading caused by the PV array onto the adjacent property. o Aesthetic impact of the PV array. o Accessibility of garages to the individual units. o Additional cost for separate PV ground mounted arrays (as opposed to mount­

ing the PV arrays on detached garages).

A total of six alternate layout schemes are evaluated. Appendix B includes plots of each of the schemes and discusses advantages and disadvantages of each arrangement. The site layout ultimately selected is shown in Figure 4-1. The PV arrays are located on jointly owned garages located at the back of the detached houses. The basic advantage of this arrangement is that the array is mounted off the ground (away from vandals) and on a useful, maintained building. The aesthetics of the lay­out is also acceptable. The major disadvantage is the higher land use compared to some of the alternate schemes. Figure 4-2 shows the same layout for the Northern house with an adjacent cluster. The corresponding garage and house units are identi­fied by numbers. The houses at the end of the cul-de-sac are the most removed from access to the garages.

In general, the use of detached separate garages in a cluster is common with attached housing developments but is seldom used with detached dwellings. One of the reasons for the purchase of detached homes is the possession of a private domain . Locating garages remotely from the residence is not appealing to the detached home

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Scheme IIFIl

10 lots @ 6000 s.f.l.a. avg. Road R.O.W. P.V. land area 78'x17S' Tota 1 land area

Shading control area

Total land area/d.u. Total road R.O.W./d.u. Total P.V. area/d.u.

" I '¢' I P.V. cell area '" II' P.V. array angle Qt 1h P.V. array max. he'gnt ~ b: ~ Min. angle far no shading ;~ ';:: I ~.1'It>N COl11llents

60.000 s.f. 14.800 s.f. 13.650 s.f. 88.450 s.f.

approx. 5.000 s. f.

8.845 s.f. 1.480 s.f. 1.365 s.f.

10.000 s.f. 28' 20' 26'

~ 'parking road lncl. 1" P.V. land area , 'garages under P.V. array

L..... - _ • length of P. V. arrays visually objectionable -requires additional area for shading control

; za' - qz! _~_.n __ -J :z.$~_J. .. ~' __ l LEI -of-~~~'~\I-r--- ~ - . I"':'v, A~"'"

't5!:ip.Me. 11~11 ~ 211&= :zec::.Tl0N _ IS; 4' .. 40'

Figure 4-1. Selected Southern House Site Layout

t.:iLJ1 t-----

Figure 4-2. Northern D~tached House Site Layout 4-6

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buyer. However, the alternative of mounting the arrays on separate structures which use valuable ground space does not provide any function other than array support and negative aesthetic aspects, is much less likely to be accepted than the garage mount­ing of the arrays.

In summary, if separate PV arrays are used for a cluster of detached dwell­ings, it is prudent to mount the arrays on buildings that will have a useful func­tion. The only available accessory structures associated with detached residences

are garages. If a requirement of a 75 to 95 square meter array per dwelling unit is needed, a normal garage roof is not adequate to accommodate the array. While the additional space under the array can function as useful storage space, it does im­

pose an added cost. The additional size of the garage allows a substantial storage

area. However, its remote location from the house somewhat reduces the security of the storage area. On the positive side, with a separate cul-de-sac for automobile

parking, the main access street to the buildings can be pedestrian-oriented, with pavements, a narrower street, and a visual barrier for casual automobile traffic.

With the garages clustered together in a separate cul-de-sac, each of the units

• would have more available yard space around the house, or conversely, the units could be placed closer together with the same amount of yard.

•

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Description of Building Designs

This section provides a description of the residential dwellings selected for this study.

Single Family Detached - Northern House An initial design was prepared for a house with the PV array mounted on the

dwelling unit. This design (Figure 4-3) is briefly described as it represents a point of departure for several of the other designs.

The primary design requirement for the Northern house is a need for a large

rectangular roof area, tilted at 400 from the horizontal, with a floor plan area of 1600 to 1700 square feet. Because of the relatively steep roof slope, the large roof area either has to be nearly square, covering two full stories of a two story

building or has to have a short slant height and be relatively long for a one story structure. A two story unit is chosen because of the need to accommodate narrow

4-7

..,. I

co

•

_t c.&e".tiotl

- --

" , " . ;, I I I ';, .

II] lJll] I' ' : ;. ',I

,

r= ,,:

i~ I :1 i .,

, - --,-- , , Ii .,j I

:['1 1 , .• ! •• '

'-u' ,i' , :",'

I;,!! I: '

II

lm [D ..

I ;i' 1" ;,

CO [[[]

~t .&e"atior\

South Facing Roof Area 993 ft2

, ,~o/ '-"-.0",

"

t---

ITTI I

D rr=

~D !

tIOt't~ .!-uatiOI/l -~ eiouatiof'l

Figure 4-3. Elevations of Northern House with Roof Mountpd PV

• • • •

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•

sites. A two-story building is also more common in the Northern tier. This approach allows the possibility of attaching several of these buildings together to produce a row house. The plan that is developed can be entered either from the south or the north, making it necessary to separate designs for the two sides of the street.

The large roof area required results in a second floor which is wider than the first floor. For this reason. the two car garage attached to the house is par­tially covered by the master bedroom. The garage, like the front door, can be located either on the north or south side of the house. If the garage is on the north side, a small den or greenhouse is provided next to the living room on the south. For the garage on the south side, a den is provided on the north, but with fewer windows because of the non-solar orientation. An equipment room is located between the greenhouse/den and the garage.

Besides this small extra space, the first floor has a 1 iving room, a dining area, and a kitchen; the second floor has three bedrooms and two full baths. A central feature of the plan is the staircase, which floats freely in the middle of the space. The popular option of a basement (desired by most homebuyers as of 1980)

is provided by extending the stairway down. The basement extends only beneath the kitchen, dining room, and staircase -- the living room, garage and den are all on a s 1 ab-on-grade.

When the requirement for the PV array is removed from the house, and mounted on a detached garage or cluster of garages, the plan changes dramatically (Figure 4-4). First, the roof slope is reduced and clerestories are broken through to provide south light into the second floor and an increased amount of passive gain. Second, the space liberated by the removal of the garage is occupied by the master bedroom, which is brought down to the first floor. This leaves only two bedrooms upstairs, and changes the design into something approaching a classical "Cape Cod" design (Figure 4-5). The master bedroom is always on the south side of the house, with a mechanical and storage room on the north side and a bathroom and closet in between. If a basement option is desired, it could extend under the entire house (although leaving a strip of concrete slab along the south side of the house can provide storage for the passive gain through the windows). North windows on the second floor are provided for both bedrooms, to add light and to provide for thermosyphoning

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In other respects, the house is similar to the design with PV on the roof. The area is increased by 90 square feet; however, the simpler construction (there is no cathedral ceiling in the living room) and more compact design will probably re­sult in a cost similar to the original design.

Single Family Attached - Southern House The southern house design (Figure 4-6) is similar to that developed in Ref­

erence 1 with the PV array removed. There are two floor plans. One plan has a southern entry and the second plan has a northern entry (Figure 4-7). In both plans, the house is broken into two zones. A living/dining/kitchen zone is on the east side of the house, and the bedrooms and baths zone is on the west side of the house.

In the south entrance plan, a corridor runs from the south front door to the north rear door. Adjacent to the entry is the living room which has a large dining alcove. The dining alcove is adjacent to the U-shaped kitchen containing an eat-in breakfast area. Acting as a central divider is the equipment room and laundry. A

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branch corridor leads to the three bedrooms, two of which are on the south for passive • solar gain. The master bedroom is located on the north with its own bath. This bath is next to the second full bath which serves the entire house. The living/dining area has a cathedral ceiling, with a clerestory facing north, which can be seen on the elevation. These clerestories provide thermo-syphoning ventilation in the summer­time. The elevations also show generous overhangs to protect the south windows from summertime sun. The entry recess and the offsets in the plan help to add interest to the basic rectangular layout.

The floor plan for the north entry design yields a larger living room because the corridor from north to south is absent. Both the living and dining rooms face south, with the equipment room between the entry and the kitchen. This layout is generally a more satisfying arrangement than the southern entry plan. The bedroom portion of the house remains the same.

Garages

There are four combinations of location and orientation of the garage accord­ing to the suggested site layouts shown in Figures 4-1 and 4-2. These combinations

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the garage located on the north of the parking area (labeled "North Garage" in Fig­ure 4-8) has the PV array area facing the parking lot. The "South Garage" has the PV array area facing the back of the house. Figure 4-9, labeled similarly, shows the Northern garage elevations. Additional details are shown in Figures 4-10 and 4-11 for the Southern and Northern garages respectively.

The Northern garage located to the north of the parking area poses a serious visual problem because of the height of the ridge above the ground. The ridge can be as high as 26 feet from the ground depending on the array area required. This produces a very high and very wide blank wall facing the backyards of the houses on the south side of the street. These houses have south facing windows which look di­rectly at the blank wall.

To produce a tolerable visual appearance, an alternate scheme, with a 22 foot slant height is suggested. This change allows the north side to be stepped, by the introduction of a ventilating clerestory and a short roof sloping north. See Figure 4-12. The "South Garage" can still retain the design shown in Figure 4-9, because it faces only onto the driveway serving the garages.

The southern climate design does not pose the same height problem, because

the slope of the roof is much lower (6 on 12 instead of 8 on 12). Even so, the north wall of the north bank of garages is still very austere. A small break in the surface of the wall and introducing small roofs over the entrances, break up the monotonous visual character of the wall.

In all cases, there are continuous louvers at the ridge to provide ample ven-

• tilation. Because the garages are longer than needed for two cars per house, the extra space is used for storage. An equipment room is located near the middle of the plan. Three of the garages are entered directly from the backyards of the abut­ting houses; two are entered via a passage from the east (or west), in the northern design. In the southern design, the two end garages are entered via the garage door side, with a path serving the end units.

• Single Family Attached - Northern Row House

The floor plan of the Northern townhouse is identical to that of the northern detached house with PV on the roof, except that the three bedrooms on the second floor

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are arranged such that they all face north. This eliminates the need for east or west windows. As can be seen in the perspective of a four unit cluster, Figure 4-13, it is desirable to offset the units to avoid the monotony of a continuous 400 square meter PV array. This produces some self-shading, and may require the elimina­tion of the array from part of the roof.

In the rowhouse design, one of the two garages is removed to allow the build­ings to adjoin. However, by flipping each alternative plan end-for-end, it is possible to put two garage doors adjacent, allowing two driveways to be consolidated. The extended projection on the north side helps to relieve the monotony of that elevation.

The northern rowhouse site plan, Figure 4-14, illustrates several clusters of six and eight buildings, with the beginnings of four building clusters shown on the right side. An actual site would exhibit more physical constraints, and might require the buildings to be slightly off-south or might require more severe offsets in the rows. Notice that landscaping, especially tall trees is generally restricted to the north side of the buildings, in order to avoid shading the PV arrays. Figure 4-14a shows an elevation of the rowhouse.

Single Family Attached - Southern Multiplex As shown in the perspective (Figure 4-15), the southern multiplex is made up

of a series of very large sheltering roofs containing the PV array. Again, for visual interest, the roofs are offset resulting in some self-shading and the necessity for deleting the array next to the notch. In Figure 4-16, a pair of shared garages are seen at both the east and west sides of the building, with the entries adjacent to the driveway. The units to the south have a private yard facing south. The entry is adjacent to the two lower bedrooms (Figure 4-17) with stairs to reach the third bedroom on the second floor. From the entrance, a hall passes the kitchen to reach the living/dining room. A compartment bath is located downstairs and another full bath upstairs. Some passive solar gain is available in the living/dining room and the master bedroom.

The units to the north have the master bedroom suite downstairs and two bed­rooms upstairs, located over the garages. As shown in the north elevation (Figure 4-16), these bedrooms have windows to the north in addition to clerestory windows which provide summertime ventilation. Downstairs, the living room and kitchen are

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Multi-Family - Low Rise Garden Apartments Figure 4-18 shows a perspective of the low rise garden apartments. Two roof

areas are available for the PV array. Space available on the lower roof is basically an optional area. Utilizing this· space, due to the differences in slant height from the upper roof, can present design problems for module electrical layouts. The units are clustered in groups of four around an entry, and therefore are categorized as "entry walk-up" units. The lower unit in the plan (Figure 4-19) is a two-bedroom apartment entered by walking down a half-level from the entrance. The living and dining areas face south, with the kitchen in the center of the plan behind the dining area. These three spaces are located one half level below the two bedrooms and bath which occupy the northern half of the floor plan. As shown in Figure 4-20, Section "A-A", this results in a one-and-one half story living space, partially covered with a cathedral ceiling under the lower sloping roof.

The upper unit has the living space on the first level, with a generous roof deck facing south. The kitchen is to the left of the entry, the living room straight ahead to the right and the dining room straight ahead to the left. A small deck is also located off the dining room for outdoor eating in the summer. To the right of the entry, there is the entrance to the southern roof deck, and the stairway to the two bedrooms and bath on the second floor. One of the two upper units also gains

access to the roof deck located over the public hall. As shown in Section "A" of Figure 4-20, the living room in the upper unit also has a cathedral ceiling. Clere­story windows are included in the upper bedrooms, which provide thermo-syphoning ventilation for summertime cooling, an important feature for spaces under the roof.

While the units can be attached in groups of any length, groups of two and three entries (eight and twelve units) are shown in the plan and perspective. Garages

would occur in separate buildings as shown in the site plans and described elsewhere in this report.

The site plan for the garden apartments is shown in Figure 4-21.

Housing for the Elderly

The perspective (Figure 4-22) shows a view of the housing for the elderly building from the south (entry) side. The basic concept consists of a series of steps

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leading up to the main block of the seven story building at the north as seen in the elevation of Figure 4-23. At each step, there is a large PV array with the space under the array closed by metal panels. Balconies off all the units provide shade

and protection from the strong sun in the southern climate for which this building was designed, and also provide substantial additional roof area for the PV arrays.

Taking advantage of slight variations from optimal true south orientation,

the main block of the building and the eastern wing face 150 southeast, while the western wing slants 150 to the southwest. This opens up the entry court, and re­duces the stiffness and congestion that would take place if the building were recti­linear. In addition, each step also offsets to the side, further opening up the

entry court and providing additional privacy for the units.

As shown on the floor plan (Figure 4-24), elevators are located at the cen­ter, equally accessible from all the units. Public spaces are located on the south

side of the first floor. There is no central eating facility in this design.

There are two basic one-bedroom unit plans (see Figure 4-24a). One floor plan for the main block of the building and a second plan for the stepped wings of

the building, where the corridor runs at an angle to the units. In the latter units, some space is taken out of the living area to provide a generous U-shaped

kitchen, while additional space is added to form a corridor between the bedroom and the bathroom. This unit is about 10% larger than the former unit, which follows the well-developed format of other Massdesign Housing for the Elderly projects. Some of the features of this plan are a generous amount of storage space; a pass-through

between the kitchen and a small dining table in the living room; good privacy; ample furnishable walls; and other detail features. The few required handicapped units

can easily be accommodated in the same space by suitable plan modifications.

The two-bedroom units which account for 9% of the 154 units in the building, all occur in the main block, and consist of the addition of a second bedroom to the

standard one-bedroom plan. The space previously occupied by the bathroom now be­comes a large storage cabinet. These units all occur at corners, so that the second

bedroom does not have access to the balcony .

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The mobile home (Figure 4-25) is a standard single-wide 14' x 70' unit. The front door opens into the end of the kitchen, with a dining space to the left and living space to the right. A corridor runs along the back wall of the mobile home connecting the bedrooms and opening to a back staircase. The single bathroom, with the adjacent laundry, is located between the last two bedrooms. No attempt has been made to provide for passive solar gain, or to modify the standard plan of a mobile home unit. All of the innovations in the mobile home design occur in the detailing .

The mobile home site plan (Figure 4-26) shows 100 units, and is typical of a contemporary mobile home layout. In this design, the road network is quite irregu­lar, while the mobile homes themselves are all oriented orthogonally to create a certain amount of order in what is otherwise naturalistic pattern. A community building is located at the entrance. A plan for locating all the units with a south facing roof area would be impr"actical. A centrally located array would therefore be used for this RLC type.

Description of Energy Conservation Features

Single Family Detached Homes (Northern and Southern) Wood frame construction with a slab-on-grade is assumed, modified to meet or

exceed good energy conservation construction for 1980. The walls are six-inch stud construction, filled with R-19 fiberglass. Exterior insulating sheathing is not used, partly because of problems in controlling vapor, and partly because it is felt that the wood membrane on the exterior of the building contributed substantially to its overall structural integrity. Some special features made possible by the use of six inch studs are included. For example, headers over the window are either sepa-

• rate 2 x 4 members with two inches of urethane insulation between them or a built-up beam using plywood nailed and glued to a top and bottom cord, filled with fiberglass insulation. Either method substantially reduces the heat loss through headers. In addition, at points where a second floor frames into the wall, the joists are held

back two inches from the outside face, and that space is filled with two inch ure­thane insulation. This again removes a serious cold bridge in a two-story building.

• At the edge of the slab-on-grade, the foundation wall is held back two inches

from the face of the sheating, and the space is filled with two inches of polystyrene

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•

•

•

•

.t:> I

.t:> .....

• • • • +

" 11:3<l' . "-" . __ .- ----,. ------

-+ 1000' ~----- .~---.----"---"------- ----- --- -----==-=:--=::~_=___===~~----f--

_ , -r--- ell CoLL=TOJO:.. MI<A'l''' ~ , III .j)

s "

SIT~ FLAN ~~ I" ~ KD'

, I

I-I:lf::nI

$

Figure 4~26. Mobile Home Site Plan

,

", .. ?"" I --iI!-..

,

Scheme 8.1

lOB lots @ 4000 s.f. ov9. Roads, recreation. open space Subtotal land area (14.2 acres) P.V. land area 165 1 x 1130' Total land area (IS.5 acres)

7.6 Idts/acre w/o P.V. area 5.8 lots/acre wi P.V. area

Total land acres/lot Total P.V. land area/lot

Total P.V. cell area P.V. cell area/lot P.V. array angle P.V. array maximum height Minimum angle for no shading

•

432.000 s.f, 186.100 s.f. 618,100 s. f. 186.450 2.o!, 804,550 s. f.

7,450 s. f. 1,726 s.f.

70,000 s. f. 650 S.f.

35 0

24 ' 21 0

insulation, running down the outside of the foundation wall. This, in turn, is covered with weatner and rodent-proof protective material.

At the roof, specially fabricated one inch-deep panels of inexpensive cardboard

are nailed to the underside of the sheathing. This provides a guaranteed ventilation air passage directly beneath the sheating. This leaves approximately 8 inches of

space in a cathedral ceiling situation. Nine inches of fiberglass insulation can be

compressed in this space yielding an insulation R factor of 25. In the attic, two

layers of R-19 insulation are laid down on the ceiling, with cardboard air passages

nailed to the underside of the roof where the fiberglass meets the eaves (thus guar­anteeing air passage at the edge of the ceiling). All attics are amply ventilated at the gable end.

Exterior doors are thermal-break metal with urethane insulated cores. Based

upon a number of references, it was felt that air-lock entries were not cost-effective. For additional insulation, storm doors are applied outside the insulated main doors.

•

•

Windows are tight-fitting wood sash, either fixed or casement, with double- • glazing on the southern exposures and triple-glazing everywhere else.

R-7 insulation is used below the concrete floor slab. Where the slab is ex­posed to passive solar gain, a hard surface such as quarry tile, brick, tile, or ex­

posed concrete is used. Elsewhere, the slab is covered with carpet and padding. Figure 4-27 summarizes the conservation features.

Northern Row House, Southern Multiplex, and Multi-Family Garden Apartment

The construction of these buildings is identical to that in the group above, with the exception that between each dwelling unit it is necessary to provide code­

required fire-proof partitions. These partitions have to extend out to the exterior sheathing of the building, and no floor framing is typically allowed to rest on these

partitions. This wi 11, in a minor way, modify the insulation at the party wall, but is not considered to affect the thermal load in a way which could be detected. With

buildings of this scale, it is not necessary to extend the party wall thorugh the

roof to form a parapet wall, which would case shadows on the PV array and interrupt it.

4-42

•

•

+> I

+> W

• • • • p /

I R-25 (8") F.G. J-UPPER CHORD OF

,ROOF TRUSS COMPOSITION SHINGLES ~~

1/2" PLYWD~~ SHTHG g.' 2 LAYERS R-19

" FIBERGLASS INSULATION

, ,LOWER CHORD OF METAL ROOF AN~

~TERIOR FIN,ISH"

ROOF TRUSS"

GUTTER-

OUTSIDE JOISTS

TRIPLE GL ~-

I'. OOF TRUSS

ATTIC CONDITION

1/2" GYPSUM BD.

I----·

INSULATED -METAL EXTER. . DOORS

2x6 STUDS --l1F=11 W/R-19 F.G. INSULATION

R-10 INSUL. OUTSIDE FOUNDATIONS (PROTECTED)

-4" FLOOR SLAB

'~~iI2qH¥"'- R-7 INSULATION BELOW SLAB

TYPICAL WOOD FRAMF. CONSTRUCTION

~ m\ri~ " ", i '",,~R-19 INSULATION

"'GYPSUM BD CLG.

1 1/4" INSULATED METAL DOOR wI STORM DOOR

']1, .

-j -------METAL SASH wI THERMAL BREAK

2x6 FLOOR JSTS

& DOUBLE GLAZING

DROPPED FLOOR SECTION WI WARM AIR DUCT I (INSULATION SQUASHED

TO 4" @ DUCT)

SCALE: 3/410 .., 1'-0"

Figure 4-27. Mobile Home Energy Conservation Features

•

Housing For the Elderly Because the housing for the elderly is a seven-story, mid-rise building, it

must be made of fire-proof, non-combustible materials. There are a number of struc­

tural systems which would satisfy the code requirements. Based upon recent experi­ence, concrete block bearing wall construction with pre-cast concrete floor slabs

resting on the bearing walls is used. The exterior skin is a concrete block and brick cavity wall.

•

In order to control heat loss in a building of this type, it is necessary to ...

make sure that a continuous skin of insulation surrounds the building structure. The exterior finish brick must be outside this insulating layer, and it is important

that the steel which extends through this layer to support the brick not be con­tinuous. Rather, the shelf angle that supports the brick must be held away from the

concrete block, and supported by intermittent metal angles, allowing the insulating blanket to run behind the angle to prevent a serious cold bridge. At the roof, the

insulation continues up and over the roof deck, with the built-up roof on top of the insulation. Two inches of urethane (or polyisocyanurate) are used on all walls;

three inches of urethane are used under the roof membrane.

The windows are thermal break aluminum sash with double glazing. Metal win-

dow construction is undergoing many changes, and the choice of sliding units or

casement sash is contingent upon whatever unit is available with the lowest infil­tration rate. Double-glazing is used throughout, since most of the units will pick

up some solar gain during at least part of the day.

The balconies which are a major feature of the design, and which extend the available roof area for applying photovoltaic modules, are not supported from the

•

main building frame, as is typically done. Supporting the balconies from the build- • ing frame creates serious cold bridges and reduces the effective insulation level of the building. Rather, the balconies are carried on separate six-inch thick pre-cast concrete sidewalls which are used instead of the brick facing as shown on the plan

detail (Figure 4-28). These sidewalls are tied back periodically to the main build-ing bearing walls and floor structures.

At the vertical offset which occurs whenever the building steps, the collector

array creates a void space covering units at different levels, and also covering the •

4-44

""" , """ (J1

• • 1/2" GYP BD =lm 2" URETHANE

• METAL THERMAL BREAK --ALUMINUM SASH WInl DOUBLE GLAZING

INSULATION ',I~~~lft~~ pjj ==I

In"GYPBD~

4"

._--''-'--L_. ____ ... _____ .. __ _

BALCONY FLOOR

TYPICAL PLAN SECTION THROUGH OFFSET BETWEEN UNIT AND BALCONY IN STEPPED WINGS OF ELDERLY HOUSING

• VOID SPACE BELOW COLLECTOR ARRAY

BUILT-UP ROOF ON URET~NE INSULATION

1

,,111, 111""1 '"'' """" ".:W:': ':~- i~S~~~~E r.--------------__ .~~r.-~~~-~~=i---MOISTURE-PROOF

8"

8" P.C. CONG FLOOR PLANK7

./

1/2" GYP ON 8" eMU

COVERING

--8" eMU

TYPICAL VERTICAL SECTION THROUGH OFFSET (SEE LOCATION HARKED IN PLAN SECTION AT LEFT)

•

SCALE: 3/4" = 1'-0"

.E1JlJ!ll.CONSERYAUlltLEfATURES MASONARY CO~.STBI.!CT!ON

Figure 4-28. Elderly Housing Energy Conservation Details

balcony ceilings. While it is assumed that some moisture will penetrate the skirt walls which are dr0poed from the plane of the array to meet the roof of the building, the brick or pre-cast concrete exterior veneer is replaced by a simple moisture­

proof covering over the insulation. Thus, wind and sun are excluded from the void space. Likewise, a simple suspended ceiling occurs over the balconies. The skirt panels below the arrays are made of painted metal on a metal frame -- the entire

structure is outside the thermal envelope of the building.

•

A maximum of energy conserving fluorescent lighting is used in the building, • especially in the corridors and public lobbies. If ground conditions permit, hy-

draulic elevators are used to cut energy consumption for elevator motors. Toilet

exhaust air is collected at central points and run through an air-to-air heat ex-changer, where heat from the exhaust air is given up to pre-heat the ventilation air coming into the building.

Mobile Homes Mobile home construction, because of severe cost constraints and because of

the small size of the dwelling unit, is notably behind ordinary site built construction in energy conservation features. It is, therefore, assumed that by 1986 the mobile

home industry will have reached the 1978 level for high-quality, site-built homes.

Exterior walls retain the 2 x 4 construction of current practice, but with

the wall cavities completely filled with R-11 insulation rather than the current standard of R-7 (Figure 4-27). The cornice height of the roof truss is raised to

allow a continuous blanket of R-19 insulation to run all the way to the exterior walls, rather than current practice which compresses the insulation at the eaves.

Similarly, a continuous blanket of R-19 insulation runs under the entire trailer, and drops down below the warm air duct, where the insulation is slightly compressed

to four inches in thickness (compared with current practice of compressing the in­sulation to about three-quarters of an inch).

The front door is an insulated thermal break metal door with a weatherstripped storm door. Windows are sliding metal sash with a thermal break and double-glazing. It is assumed that the sliding sash will be substantially better than current models, with improved infiltration control. In general, an increased use in caulking re-

•

•

duces the already relatively low infiltration rate in the trailers. Because of the ~

4-46

•

•

•

•

•

confined space in the mobile home, the low infiltration rate requires the addition of a small air-to-air heat exchanger to maintain air quality.

Fluorescent lighting is used wherever possible, with portable task lighting

rather than built-in lighting favored throughout. The water heater, which is nor­mally put in an exterior compartment, is included within the heated envelope of the building, so that skin losses will be useful in the wintertime. The heating plant will not change, except that more efficient units will be used. Typically, the heater is located more or less in the center of the plan.

All designs assume the use either of thermal curtains, thermal shutters,

thermal drapes, or more sophisticated glazing which can trap radiative heat. The buildings were modelled with an overall R factor of 5 at the windows for ten hours per day.

4.1.

References

E. M. Mehalick, et. al., The Design of a Photovoltaic System for a Southwest All Electric Residence, SAND 79-7056, February 1980.

4-47

•

•

•

SECTION 5 RESIDENTIAL LOAD CENTER ELECTRICAL LOAD DEFINITION

Summary

Residential electrical loads, other than space heating and cooling, are divided into three categories: baseload (i.e., miscellaneous appliances and lighting); cook­ing and clothes drying; and domestic hot water. This division facilitates the sub­stitution of other primary energy sources for electricity in conducting comparative performance/economic analyses.

Hourly load profiles are developed in each electrical use category for the residential housing models selected for evaluation in the study.

• Single Family Attached • Single Family Detached - Townhouse • Multi-Family - Low Rise, Garden Apartment • Mobile Home - Single Wide Unit • Housing for the Elderly - Mid Rise, Congregant Living

Diversified electrical load profiles are developed for a single family detached home of approximately 1600 sq. ft occupied by a family of four. These profiles are also applicable to the single family attached townhouse having approximately the same floor area and number of occupants. Utility data indicates that apartment and mobile home electrical consumption patterns resemble the patterns found in single family attached/detached units. The primary difference being the level of use which is

• strongly influenced by the floor area and number of occupants in a residence. A summary of average annual electrical energy consumption by use category, for a single family home, apartment and mobile home is presented in Table 5-1.

• Electrical consumption profiles for the congregate living housing for the

elderly were developed separately, in view of the different life style of this group as well as the special facilities found in retirement housing. Though basically an apartment building containing primarily single bedroom apartments, the congregant facilities impose additional energy loads. These additional loads are defined in com­bination with the apartment loads on the basis of one thousand square feet of build­ing floor space. In addition, a daily elevator load profile is developed. Domestic

5-1

Ul r

N

•

RESIDENTIAL CATEGORY

SINGLE FAMILY

APARH1ENT

t·lOBILE H0I1E

HOUSING FOR ELDERLY

CONGREGANT LIVING

•

Table 5-1

Summary of Average Annual Electrical Energy Consumption By Residential Housing Type

1977 BASE YEAR

-

APPROX. CLOTHES DOMESTIC FLOOR AREA BASELOAD COOKING DRYING HOT WATER

(FT 2) (kWh) (kWh) ( kWh) (kWh)

1600 5540 1190 1030 4930

900 4080 1190 980 4360

980 4175 1190 980 4360

I

BASELOAD, COOKING & CLOTHES DRYING DOMESTIC (INCL. APARTMENTS & CONGREGANT FACILITIES) HOT WATER

(kWh) (kWh)

7000/1000 FT2 OF BLDG. 1970/APT. FOR

ONE 3940/ APT. FOR

TWO

• •

TOTAL (kWh)

-,

12700

10610

10705

ELEVATOR (kWh)

8395/ELEV.

•

•

•

•

hot water profiles are derived based on typical apartment use, adjusted for one or two persons, as appropriate for the smaller apartments in a retirement home. Table 5-1 also summarizes the annual loads for housing for the elderly.

Seasonal and regional adjustment factors are developed as necessary for each category of electrical energy consumption. As presented in Table 5-2, seasonal pro­files are identified for base load and domestic hot water. No significant seasonal variation could be discerned for the combined cooking and clothes drying category. For regional differences, only domestic hot water adjustment factors are identified.

Table 5-2 Seasonal and Regional Effects on Load Definition

Seasona 1 Regional Variations Differences

Base load Profiles for None 4 Seasons Significant Ident ifi ed

Cooking & None None Clothes Drying Significant Significant

Domestic Prof il es for Regional Adjustment Hot Water 4 Seasons Factor Identified

Ident ifi ed

Projected reductions in the 1977 base year energy use are postulated for each electrical use category for the years 1986 and 2000 and are presented in Table 5-3.

• These reductions are based on anticipated changes in use patterns (i.e., conservation) necess itated by hi gher energy costs, mandated app 1 i ance effi ci ency improvements and

•

a continued trend toward reduced family size.

All of the profiles discussed in the following subsections are plotted for the 1977 base year. The projected adjustments in Table 5-3 can then be imposed as re­quired •

5-3

• Table 5-3

Summary of Electrical Demand Projections for 1986 and 2000

1986 Projection Effects 2000 Projected Effects From 1977 Base Year From 1986

(9 Year Period) (14 Year Period)

Baseload Reduce by 1-1/2% Per Year Reduce by 1/4% Per Year Total = 11-1/4% Total = 3-1/2% •

Cooking & Reduce Cooking 1% Per Year Reduce by 1/4% Per Year Clothes Drying Reduce Drying 1/2% Per Year

Total = 6-3/4% Tota 1 = 3-1/2%

Domestic Reduce by 1-1/4% Per Year Reduce by 1/4% Per Year Hot Water Total = 11-1/4% Tota 1 = 3-1/2%

•

•

• 5-4

•

•

•

Electrical Loads

Single Family Detached House The electrical loads defined in this section are those attributed to a single

family detached home of approximately 1600 sq. ft., having three bedrooms, two bath­rooms, the normal complement of major appliances and occupied by a middle income fami ly of four.

Baseload -- In GE's Regional Conceptual Design and Analysis studies of Resi­dential Photovoltaic Systems (Ref. 5-1), data for a single family house taken from sixteen different sources is averaged to estimate annual base load consumption. This annual value is then used to adjust seasonal diversified 24 hour profiles. The seasonal profiles represented an average of data obtained from MIT Lincoln Labora­tory (Ref. 5-2) and Public Service Gas & Electric Company of New Jersey (Ref. 5-3 and 5-4). The information from both these sources was based on metered data from statistically sampled groups of homes (usually thirty to forty homes used in most load research studies).

Since these seasonal baseload profiles represent both diversified demand as well as average annual consumption, they are deemed appropriate for use in the ana­lysis of residential load centers. However, an evaluation was undertaken to deter­mine what adjustments, if any, to these profiles, may be necessary as the groups of homes comprising a load center are varied from approximately four to twenty units.

Diversified average daily profiles for groups of three to fifteen homes, each with the same basic major electrical appliances were obtained from Arizona Public

• Service Company (Ref. 5-5).

•

Arizona Public Service Company has been collecting metered data from single family residences since August 1977 in connection with an on-going data collection program. The metered data, as well as the characteristics of each home and its as­sociated complement of appliances, are stored in a computer for use by the Utility in conducting a variety of load research studies. A number of existing computer printouts of diversified average daily load profiles for each month of the year for small groups of homes (i.e., three to fifteen), each with the same set of appliances, were made available to G.E.

5-5

Diversified demand plots were drawn for each of three house classes, a class being defined by its set of major electrical appliances. Data was available for two different size groups of homes in each of the three classes, which fortunately per­mitted comparison. The average daily demand profiles for January are presented in Figure 5-1.

Analysis of these plots indicates that for groups of up to 15 homes no trend

•

could be identified with regard to lowering of peaks or the shift of peak demands ~

with increased number of homes in a group. In one of the three cases, Group #11, where both groups had the same average floor area, the larger group of homes had higher peaks and larger daily energy use. Where the larger group of homes may have exhibited lower peaks, as in Group #10 case, we note the larger group had an average

home size 300 sq. ft. less than the smaller group and used less daily energy. In Group #8, each of the groups took turns at exhibiting a higher peak during the day.

The conclusion is that a different pattern of energy use or smaller average home size may have accounted for lowering a larger group's peak rather than in­creased diversity due to increased number of homes. Therefore, no definitive trend in change of shape or magnitude of the daily load profile could be established when group size increased from three to fifteen homes.

As a result of this evaluation, the seasonal profiles prepared in the Re­gional Conceptual Design and Analysis Study are used directly since they represent an average daily use based on many.sources of information and are developed from di­versified hourly data.

•

These seasonal load profiles are presented in Figure 5-2. The vacation per- • iod profile superimposed on the summer daily profile reflects the operation of the refrigerator/freezer and miscellaneous clocks, night lights and dehumidifier which in most cases continue to operate when the occupants leave.

The impact of weekends is also evaluated in the Regional Conceptual Design and Analysis Study. It was determined that a 7.5% variation from average daily use was possible on weekend days. In view of the limited weekend data available and the fact that the variation fell within the spread of data on annual energy use, it was decided to use the average weekday profile for weekends.

5-6 •

•

•

•

•

•

~ /'

/ _/ <- ,C __

~ ~-:::..",)---, '." -I

,

'. )

5-7

V1 <lJ

!6 u.. <lJ

en c: (/)

~

3: ~ I

0 W Ul ~

G It: w Z w

1.1

1.4

I.Z

o

."REPRESENTATIVE" HOUSE - 3 BEDROOMS

.4-MEMBER FAMILY

.ANNUAL ENERGY USAGE FOR 1977 - 5540 kW HR/YR

1.6

'0. WINTER 1.4 (b) SPRING

i.2

1,0

0.8

0.6

0.4

0.2

M lAM 4. 6 8 10 NOON 2PM" 6 o 8 10 N

o o

'N

2 4 6 8 10 M PM

1,6

1.4

1.2

1.0

0.8

(0,6

0.4

0.2

0

HOURS OF DAY

1.6

(c) SUMMER 1.4

1.2

1.0

0.8

0.6

.r.r-......... 0 4 ~ _____ r ~~ •

~, __ J_-_~ ____ ~r- _

ENERGY USED: 13.00 kWh/DAY 0.2 __ VACATION ENERGY USED:

8.05 kWh/DAY , I , , I ! 0

M 2 4 S 8 10 N 2 4 6 8 10 M AM 0 PM

o N

HOUR OF DAY

6

R , , , , (d) FALL , I

Jb R P b , I I I , I I I ! I I I I I rl I q I I I I I L I I J I r, I I I r L_ .. .J I _, I I! !.... I

I 0UlJi-J~- I f L~ QI , L ,

ENERGY USED: 15.58 kWh/DAY -WEEKEND ENERGY USED: 16.75 kWh/DAY

Figure 5-2. Seasonal Characteristics of Baseload Electrical Demand Profiles

5-8

•

•

•

•

•

• No regional variation that would significantly affect these baseload seasonal profiles has been identified. Consequently, the same baseload profiles is used for

all regions to be studied.

Domestic Hot Water -- The Regional Conceptual Design and Analysis Study also

developed a dai ly profi le for domestic hot water usage and

sumption value based on averaging several sources of data. without adjustment for seasonal effects because of lack of

an average annual con­

This profile was used

data. However, addi-

tional data has since become available to permit adjustment of this yearly average

• domestic hot water profile for seasonal variations. These seasonal variations are due primarily to the changes in ambient temperature over the course of a year.

•

•

Average daily demand profiles, by month, are available from the Alabama Power

Company. Also monthly variations in load levels are available from a MIUS study conducted by the Oak Ridge National Laboratory (Ref. 5-17). Both sets of data are averaged in terms of a monthly percent of annual use and seasonal correction factors

are derived as shown in Table 5-4. The final seasonal profiles used in the study

are shown in Figure 5-3.

An adjustment to the summer profile to account for a reduction in domestic hot water use during the vacation period is indicated on the summer chart .. The vacation period energy use represents the continuous losses of heat transfer through the tank walls and adjoining piping. These losses are based on the assumptions that

electrical power to the domestic hot water heater will not be switched off when the

residents depart for vacation. The average daily summer profile has been reduced by

78.8% based on estimated energy losses of 21.2% specified in Reference 5-7.

These basic seasonal profiles must also be adjusted to account for diffe­

rences in well water temperature throughout the U.S. Figure 5-4 (Ref. 5-6) provides approximate average well water temperatures to be found across the U.S. Correction

factors, to be applied to the basic domestic hot water seasonal profiles, for each

of the thirteen representative cities in the regions studied in presented in Table

5-5. The profile and absolute load level can be reduced significantly with the addition of a solar hot water system as discussed in Section 10, Table 10-12.

Cooking and Clothes Drying -- Cooking and clothes drying energy loads differ

• from baseload electrical use in that they may be satisfied by energy sources other than electricity. Consequently energy use profiles for these applications are de­veloped separately.

5-9

Table 5-4 • Domestic Hot Water Seasonal Correction Factor for Baseline Profile

Percent of Annual Use Alabama Seasonal

MIUS Power Correction Study Co. Study Average Factor

Dec 10.5 10.6 10.6\ Jan 11.4 11.8 11.6 32.5 Winter Feb 11.0 9.5 10.3 1.28

• Mar 10.3 9.4 9.9) Apr 8.8 8.4 8.6 } 26.3 Spring May 8.2 7.4 7.8 1.04

June 6.2 6.3 6.3/ July 4.8 6.0 5.4 ) 17.9 Summer Aug 5.9 6.5 6.2 0.92

Sept 6.0 6.9 6.5\ Oct 7.1 8.0 7.6 23.7 Fall Nov 9.9 9.2 9.6 0.96 •

•

• 5-10

• • • • • 1977 Base Year 1977 Base Year

1.6 Winter 1.3 1.5

Fall 1.4 1.2

1.3 1.1

1.2 .c 3

1.0 ~ 0.9 .c 1.1 3

~

1.0 ., 0.8 ~ :> 0.7 ., 0.9 " ~ m 0.6 :>

0.8 ~

i;l ~ 0.5 ~ 0.7 w .. ~ 0.4 w 0.6

0.5 0.3

0.4 0.2 ~ Energy Used - 13.0 kWh/Oay 0.3 Energy Used 17 • 3 kWh/Oay 0.1 0.2

M 1 2 3 4 5 6 7 8 9 10 11 N 1 2 3 4 5 6 7 8 9 10 11 M 0.1 Time of Day

. M 1 2 3 4 5 6 7 8 9 10

TiRl@ of Day 1.3 1.2L Spring

UI 1.1

I 1.0 .... 1.0 .c 0.9 I-' 3

0."9 Sunmer ~

0.8 .c 0.8 .,

0.7 3 ~ ~ 0.7 :>

" 0.6 m ., 0.6 ~

0.5 f ~ l...r-l 'L ~

~ :> 0.5 w i;l 0.4 ~ 0.4

0.3 ., ~ 0.3 Energy Used 14.1 kWh/Day w

0.2 0.2 Energy Used = 9.7 kWh/Day

0.1 0.1

r-'_ -- . -'---''1 -1- ..J-""""L ~

-.-.-.-.-. J "".,.,.+~ .... e .......... :- ii~::;:;.rl'I..".~?-'";; a..Uh In"u ~_ .,..1-"'"1- -- M 1 2 3 4 5 6 7 8 9 10 11 N 1 2 3 " 5 6 7 8 9 10 11 M

Time of Day Time of Day

Figure 5-3. Domestic Hot Water Electrical Load Profiles for Single Family Homes (4940 kWh/Year)

CJ1 I

...... N

• • Figure 5-4. Approximate Temperature of Water

from Nonthermal Wells at Depths of 30 to 60 feet (Ref. 5-6)

• •

1.

./

•

•

•

•

•

Table 5-5 Regional Correction Factors for

Domestic Hot Water Usp

Representative Regional City_

1. Boston 2. Washington, D.C. 3. Charleston 4. Mi ami 5. Bismarck 6. Madison 7. Omaha 8. Ft. Worth 9. Nashville

10. Phoenix 11. Albuquerque 12. Seattle 13. Santa Maria

Average U.S.

Factor

1.06 1.00

.89

.75 1.16 1.11 1.06

.88

.96

.88 1.05 1.05

.94

1.0

In GE's Regional Conceptual Design and Analysis Study, an annual average energy use of 950 kWh by the range cooktop/oven was based on data obtained from a group of studies. More recent data shows that range/oven use has decreased, with other types of small cooking appliances making up the difference. A 1977 study by the Associa­tion of Home Appliance Manufacturers shows that electricity consumption by the toaster oven, broiler, slow-cooking pot, fry pan, and roaster total 477 kWh per year (Ref. 5-23). Based on this information, a new cooking average annual consumption value is compiled as indicated in Table 5-6. This new annual average value of 1190 kWh was then applied to adjust the diversified hourly cooking profile from the Regional Con­ceptual Design and Analysis Study .

The clothes dryer profile developed in the Regional Conceptual Design and Analysis Study is used in this study since a literature search indicated no signifi­cant variation in annual use or profile shape. The average annual electrical use for clothes drying of 1030 kWh derived from nine different sources of data, is also re­tained.

The combined cooking and clothes drying hourly profile is presented in Figure • 5-5. During the vacation period, no energy is expended for either cooking or clothes

drying.

5-13

Reference No.

1

6

11

17

17

12

14

15

15

16

Table 5-6 Annual Residential Use of Electricity for Cooking

Data Source

Stanford Research Institute

General Electric From A.D. Little Analysis

General Electric From MIT Lincoln

Rand Corp. From Los Angeles Dept. of Water & Power

Rand Corp. From Oak Ridge National

IGT From PSE&G of N.J. (Metered Data From N.J. Homes)

Brookhaven National Lab. (For Typical Home)

GKC Inc. (Avg. of 19 N.J. Homes -1976)

GKC Inc. (Avg. of 4 N.J. Homes -1976)

Edison Electric Institute (1977)

Midwest Research Institute (1979)

Average Rounded Avg. Used For Study

Lab

Lab.

Annual Use (kWh)

ll80

ll43

1205

1200

1175

1124

1200

1178

1235

1177

1259

ll88 ll90

•

•

F01 .477* • F58 477*

COO 477*

(182 477*

*1977 Assoc. of Home Appliance Mgfs. (AHAM) study indicates 477 kWh of energy • used for the following small cooking appliances: Toaster Oven, Broiler, Slow Cooker, Frying Pan, and Roaster.

• 5-14

•

• s:: ::3 -'"

<lJ

'" :::J • >, en !.-<lJ <=

UJ

•

•

0.8

0.7

0.6 -

0.5

0.4

1977 Base Year (2220 kWh/Year)

Cooking Energy Used = 3.3 kWh/Day Clothes Drying Energy Used = 2.8 kWh/Day

Total Cooling & Clothes Drying

I-j I I 1

-i I I

JI I I

n I

1

I I 0.3 - I I

0.2

0.1

Clothes 1 -0

Drying I -1 I

I -0

I ,

I . ,-0

I 1 I I -0 I ,-0 I _._l I I

, __ 0

1 -. .-0, I I -0

1-.-1 Cooking 1_. J I~

I l-

I I I I I I -I

7 8 9 10 11 N 2 3 5 6 7 8 9 10 11 M

Time of Day

Figure 5-5. Electrical Load Profiles Cooling and Clothes Drying Single Family House

5-15

Though one would expect somewhat less cooking during the summer months, no specific data was readily available to substantiate any seasonal variation. On the other hand, it could also be assumed that more clothes drying is required during the summer months due to additional clothes washing during the hot humid weather. As with cooking, no definitive data could be identified to vary the clothes drying load by season. Intuitively, it would seem that since cooking and clothes drying annual energy use are approximately equal, the seasonal variation in one could offset the other. Consequently, for this study the same hourly profiles are used for all four seasons.

Though some minor regional differences in living patterns could affect the baseline cooking and clothes drying profile, none are readily identified for appli­cation as regional adjustment factors. In addition, since any variation would probably fall within the range of values used to determine the annual average use, no regional changes are applied to the cooking and clothes drying profile.

•

•

Total Electrical Load -- Table. 5-7 summarizes the range and average annual • use for each of the designated electrical use categories in the single family home.

Table 5-7 Single Family Home Electrical

Demands - 1977 Base Year

Load Type Range kWh/Yr

Baseload 4620 to 7550

Cooking 1125 to 1230 Clothes Drying 770 to 1350

Domestic Hot Water 2000 to 6800

Total

Average kWh/Yr

5,540

1,190

1,030

4,940

12,700

The average daily expenditure of electrical energy in the home is presented as a twenty-four hour load profile in Figure 5-6. Though baseload and domestic hot water use is varied by season in the study, their average daily profiles for the year are depicted to provide a single composite picture of total electrical energy use.

5-16

•

•

•

• .s:: 3: -""-

u • a.!

'" :::0

>, 0> S-a.! <=

W

•

•

2.7

2.6 -

2.5

2.4 -

2.3" 2.2 ..

2.1 -

o. o.

Single Family Home (Annual Energy Use 12,700 kWh)

1977 Base Year

r Total Electrical Load

" / I ~J

~~~estic I / \ lIJafer (13.5 kWh/Day) \ A (Avg. For the Four Seasons) I ~ \

/A (\ /:;1.,,)\. ' J ~\ \V .Clothes Lj ~DiYiri~L:

V (6.1 kWh/Day)

Base Load (15.1 kWh/Day) (Avg. for the Four Seasons)

Hour of Day

Figure 5-6. Average Daily Diversified Electrical Load Profile (Excluding Space Heating and Cooling)

5-17

Single Family Attached House The electrical loads for the single family detached home presented earlier

are used for the single family attached dwelling. The two story townhouse model in this study has approximately the same floor area as the detached'unit, the same

three bedrooms and two bathrooms, is occupied by a family of four and contains the same complement of major appliances. Therefore, no significant variation in energy

demand (i .e., outside the range already considered in developing the average for the

•

detached unit) or energy use patterns is expected. ~

Apartment

The multi-family model selected for study is the low-rise garden apartment building. Each apartment is occupied by three people, has approximately 900 sq. ft.

of floor space, two bedrooms, one bathroom and a complete complement of major ap­pliances including the clothes washer and dryer. The patterns of energy use by the

family in the garden apartment should closely approximate that used by the family in either the single family attached or detached home. The principal anticipated dif­

ference is in the magnitude of electrical energy used, which should be somewhat lower in view of the smaller family size and floor area, and the fewer number of

rooms compared to that found in a single family home.

Thus, the single family home electrical energy use profiles are appl icable to the apartment, if adjusted in magnitude. To determine this adjustment, a number of

studies were reviewed to obtain annual electrical consumption data for the cate­gories in this study.

•

The apartment annual electrical demands obtained from these reports are listed

in Table 5-8. For each category of electrical use ,an average of the available data • was derived. Total electrical demand for the apartment is 16.5% lower than the

single family requirements. Cooking energy use almost matches the single family consumption with clothes drying lower by 4.9%, domestic hot water down 11.7% and

baseload use lower by 26.4%. These reduction factors, summarized in Table 5-9, are applied to each of the appropriate single family hourly profiles to establish the

garden apartment daily electrical energy loads.

• 5-18

U'l I ......

<D

•

REPORT TITLE

• RESIDENTIAL [NEaGY CONSUMPTION. MULTIFAMILY HOUSING

• . ENERGY USE AND CONSERVATION IN I RESIDENTIAL SECTOR: A REGIONAL ANALYSIS

I • APPLICATION ANALYSIS OF SOLAR :

TOTAL E~ERGY TO THE RESIDEfHlAL I SECTOR - QUARTERLY REPORT .

!

• PRELIMINARY DESIGN STUDY OF A BASELINE MIUS

• Cor·1PARISON OF fHUS AND CDN-VEriTIONAL UTILITY SYSTEMS Fe, AN EXISTING DEVELOPIlENT

• ErlERG'f USE IN NEW YORK CITY HIGH RISE HOUSING (PREPARED FOR CITIZENS FOR CLEAN AIK I,iC. )

0 LOAD CHARACTERISTICS OF AN ALL ELECTRIC HIGH RISE APARTtlENT BUILDING

• ENERGY CONSUrlPTION PROFILES

L.

•

REF. NO.

22

7

3

18

19

20

12

21

• TABLE 5-8

..APARTMENT ANNUAL ELECTRICAL ENERGY DEtlANDS (SASELOAD. COOKING. CLOTHES DlI'Il1lli Mill IlMEslic Rot HATER)

ESTIMATED ENERGY-KWH/YR. REPORT ORGANIZATION NAME DATE BASELOAD COOKING DRYER DHW 'TiiTAl HITlMAN ASSOCIATES 1974 4300 1218 881 4060 10,459

4160 1218 881 2436 8,695

RAND CORP. 1975 - 1200 1000 4350 .-

INSTITUTE OF GAS 1977 4620 TECHNOLOGY .- - 3362 -

4248

NASA-LBJ SPACE 1977 - - - -. 8,468 CENTER

i

OAK RIDGE NATIONAL 1976 - - - 3505 10.515 LABORATORY

DAVID SAGE, INC. 1972 3146 - - - --

CONSOLIDATED EDISON 1967/ - _. - 6207 10,352 CO. OF N.Y. 1968

NEW ENGLAND POWER 1976/ 4021 1100 1170 6603 12.894 PLANNING 1977

AVERAGE 4082 1185 983 4360 10.231 TOTAL 10.6 0 kWh

• •

----REMARKS ...

3 STORY - 24 APTS. - 1140 SQ. FT. 10 STORY -196 APTS. - 350 SQ. FT.

APPLIANCE LOADS BASED 011 AVG. ANNUAL ENERGY CONSUMPTION IN U.S.

2 STORY - 24 APTS. - 1120 SQ. Fr. DHW BASED ON AVG. HOUSEHOLD 15 STORY - 179 APTS. - 750 TO 900 SQ. FT.

AVG. ANNUAL ENERGY CONSUMPTION FOR 496 UNIT LOW AND HIGH RISE APT. COt1PLEX (EFF. - 450 SQ. FT; 1 BED - 700 TO BOO SQ. FT; 2 BED - 1000 SQ. FT; 3 BED -1250 SQ. FT.)

4 GARDEN APT. BUILDINGS - 3 STORY - TOTAL OF 410 APTS. (EFF. - 550 SQ. FT; 1 BED -810 SQ: FT; 2 BED - 1200 SQ. FT.). 8 YEAR AVERAGE OF ACTUAL RECORDS

NYC HOUSING AUTHORITY APARTMENT BUILDINGS. AVG. BUILDING - 10 STORIES. AVG. APT. = 1012 SQ. FT.

23 STORY. 92 APT. ALL-ELECTRIC BUILDING IN NYC. B APARTMENTS SUBMETERED (4~ ROOf.1S PER APT.-AVG. OF 3.1 OCCUPANTS)

cor·1PUTER RUNS - HON., TUES.-FRI; SAT. & SUN APPLIANCE 24 HR. PROFILES. PROGRAM DEVELOPED FRor~ AEIC LOAD P.ESEARCH STUDIES AND NEW EtIGLAND UTILITIES DATA

Mobile Home

Load Type

Base load Cooking

Table 5-9 Garden Apartment Energy Demand

Adjustment Factors - 1977 Base Year

Annua 1 Percent (%) Reduction Demand To Be Applied (kWh) To Single Family Projects

4080 26.4 1190 0

Clothes Drying 980 4.9 Domestic Hot Water 4360 11.7

Total 10610

The mobile home model houses a family of three in a single wide unit, 14 ft. wide by 50 ft. long (floor area approximately 980 sq. ft.) with 2 bedrooms, one

bathroom and all the major appliances. Since a mobile home is a factory built sin­gle family residence, the single family electrical energy use profiles are appli­

cable. But, as with the garden apartment the reduced floor area and number of occupants will result in reduced levels of demand.

A very limited amount of data on electrical use in mobile homes is available for detail analysis. Though some metering studies on total electrical use have been conducted, a breakdown by the categories for this study was unobtainable. However, annual electrical consumption of the all electric mobile home loads, including heat­ing and cooling, is available from two Utilities (Ref. 5.8 and 5.9). In addition Reference 5-10 presents data which provides the average combined electrical load for heating and cooling the typical mobile home in the U.S. using various combinations of equipment. By subtracting the average of the total electrical loads from the average of the heating and cooling loads, an estimate of the other combined electri­cal loads (i.e., baseload, cooking and drying, and domestic hot water) is obtained.

As presented in Table.5-10, the typical all electric mobile home annually uses 22,384 kWh, including heating and cooling requirements. An average of 11,675 kWh are required to heat and cool a mobile home. Therefore, an estimated 10,705 kWh

•

•

•

•

is representative of the annual demand for base load, cooking and drying, and domes- • tic hot water.

5-20

c..n I

N I-'

• • • • Table 5-10

Mobile Home Annual Electrical Energy Demands -- 1977 Base Year

Electrical Energy Consumption - Total Electric Mobile Home (Annual kWh)

• Union Electric Co. (Average Based on 1,363) 22,701 Customers - 1977) - Ref. 8

• Arkansas Power & Light (Average Based on 30 Customer Metered Study 1971-1972) - Ref. 9

22,067

Average.

Mobile Home Electrical Heating & Cooling Consumption (Annual kWh)

• Electrical World, Feb. 1, 1977 (Based on 1979 Survey) - Ref. 10

• Electric Heat and Central AIC II ,006 • Electric Heat With Central AIC or Window Units 13,180 • Heat Pumps 10,839

Average

Estimated-Annual Baseload, Cooking, Clothes Dryer, & Domestic Hot Water

•

22,380 kWh

1l,675

10,705 kWh

Based on the assumption that the cooking load would be no different than that established for the single family home or apartment, 1190 kWh, and that clothes drying and domestic hot water demand would match the apartment requirements of 980

kWh and 4360 kWh respectively (since both house 3 people), the remainder of the 10,705 kWh, or 4175 kWh, represents the baseload. This baseload demand is somewhat higher than the 4080 kWh used in an apartment, which is reasonable based on the larger floor space in the mobile home.

•

The reduction factors for the appropriate single family hourly profiles to • establish the mobile home daily electrical energy loads are indicated in Table 5-11.

Table 5-11

Mobile Home Energy Demand Adjustment Factors - 1977 Base Year

Load Type

Baseload Cooking Clothes Drying Domestic Hot Water

Total

Housing For The Elderly

Annual Demand (kWh)

4175

1190

980

4360

10705

Percent (%) Reduction To Be Applied

To Single Family Daily

24.6

0

4.9

11.7

Profiles

Baseload, Cooking and Clothes Drying -- The model selected for housing the elderly is of the congregant living type (i.e., includes central dining area, social

•

and recreational facilities and administrative offices). This four or five story • mid-rise structure with elevator service is primarily an apartment building with special services for the elderly. Of the 100 to 150 apartments to be contained in the building, the predominant living quarters are one bedroom apartments (-80%) for single individuals with a few one bedroom units for two, and some 2 bedroom apart-ments. Area provided for 1 bedroom units is on the order of 700 sq. ft., with up to 900 sq. ft. for the larger 2 bedroom units. Each apartment contains the smaller size refrigerator/freezer, dishwasher and range/oven. Though cooking facilities are included in each apartment, approximately one half of the residents will participate •

5-22

• in a plan which provides three meals in the central dining area. Centralized clothes washing and drying facilities are also provided.

Although primarily apartment units, the energy consumed and patterns of use vary from that of the typical apartment building in view of the life style of the re­tired elderly. In addition the energy utilized in the congregant facilities must be accounted for in the overall use patterns.

• A typical hourly energy demand profile for retirement homes, presented in Figure 5-7, was obtained from the Ecube Applications Manual (Reference 5-11). This profile, based on metered data from a study of retirement homes conducted by Northern Gas Company of Omaha, Nebraska in 1966, includes all facilities in the building, apartments as well as congregant service areas, but excludes elevators, domestic hot water and heating and cooling. Based on the specified peak demand of 1.43 kW/1000 sq. ft. of floor space and the percent of peak demand indicated on an hourly basis in Figure 5-7, an average daily profile for a retirement home was prepared, whiCh totals 19.2 kWh per 1000 sq. ft. of building. This baseline profile was then ad-

• justed for seasonal variations using a Consolidated Edision Company of New York load research study (Reference 5-12) of an all-electric apartment building. This report provided monthly data in a category designated "general use" which compares to our study categories of base10ad, cooking and clothes drying. Although the Consolidated Edision Company data is for the typical apartment, the monthly energy use data pro­vides trends to develop valid seasonal adjustments of the baseline profile for housing for the elderly. Figure 5-8 depicts these seasonal profiles based on 1000 sq. ft.

• of floor space.

Elevator -- Energy used by elevators was also metered in the Northern Natural Gas Co. study and results published in the Ecube Applications Manual (Reference 5-11). Average daily energy use per elevator is 23 kWh based on a 15 HP motor using 15 kW during normal running operation. A theoretical load profile (Figure 5-9) is generated based on the 23 kWh of daily use.

Domestic Hot Water -- Domestic hot water use profile is estimated using an Ecube Applications Manual for gallons per hour for an apartment. Minor adjustments are made to the 12 midnight to 6 AM values in order to limit the total water used to

• 40 gallons for an apartment with two people. The 40 gallons is based on daily use

5-23

"'0 c:: rO E (]) Cl

-"" rO (])

0-

'<-0

~ I

"'0 c:: rO E (]) Cl

>, ~

s.... :::> 0 :c

100

90 80

70

60

50 40

30

20

l(l

0 12

, ! ! ! ! I !! ,

2 4 6 '8 10 12 2 4 6 8 10 12

Time of Day-Hr

Note: Peak Demand = 1.43 KW/1000 sq. ft., includes all facilities and services except domestic hot and elevators (for building sizes of 55,000 to 160,000 sq. ft.)

Figure 5-7. Retirement Home Electrical Use for a Typical Operating Day

5-24

•

•

•

•

•

• • 1.5

1.4 Winter 1.3 1.2 - Jlj\~ r-l ,] ~

'" l' ~ '" >, ~ , 1! ~

1.1

1.0

.0.4

0.3

0.2

0.1

,~

Energy Used = 22.3 kWh/Day

M 1 2 3 4 5 6 7 8 9 10 11 N 1 2 3 4 5 6 7 8 9 10 11 M

Time of Day

• 1.2

1.11 1.0 .

:i 0.9

t 0.8

~ 0.7 >,

~ 0.6

" ~ 0.5

0.4

0.3 0.2

0.1

• • Fall

}l, 01/-' --1 \

~·L_J Energy Used 0 18.4 kWh/Oay

.L..-,---,,--,---,~r------L_...L_ . .J-_ J __ ~_...J..._..L--L--.l----L.._-----L----1-...L..- • ...L' --'_-'-~

M 2 6891011 6891011M

Time of Pay

1.2

1.1 Spring 1.0

~ 0.9 U1 I

N ~ Summer

~ n ~J Ljl,_ ,-r--t ~

0.8 , e:

, ., . Ll l ~ 0.4 -,

._-.-

0.3

0.2

0.1

Energy Used 17.7 kWh/Oay

M i 4 6 7 e 9 10-1'1 N 1 2 '~ ~ I; t; ) ~ ~ lb II ~ Time of Day

'" 0.7

~ 0.6

" 0.5 c ~

0.4

0.3 Energy Used 18.4 kWh/Day 0.2

0.1 _-L..l _L-_L .. 1. __ L._...Li ! ---L. . ...L. ! I ! f ! j

M1234567891011N123456891OJlM

Tlme of Day

Figure 5-8. Electrical Load Profiles Per 1000 Sq. Ft. - 1977 Base Year Housing for the Elderly (Baseload, Cooking and Clothes Drying) (Incl. Congregant Facilities)

2.5 ~ 2.4 ~ 2.3

0.6

0.5 0.4

0.3 0.2 0.1

M

Figure 5-9.

Energy Used 23 kWh/Day

Time of Day

Elevator Electrical Load Profile Housing for the Elderly -- 1977 Base Year

5-26

•

•

•

•

•

•

•

•

•

•

of 20 gallons per person as recommended by ASHRAE (Reference 5-13). The gallons per hour profile .converts to an electrical energy profile using 11.7oC (530 F) average U.S. well water temperature (Reference 5-6) heated to 60 0C (1400 F) in 78.8% effi­cient electrical water heater (Reference 5-7). It should be observed that domestic hot water used in central facilities is accounted for in the apartment profile, based on the assumption that hot water used centrally (e.g., in the dining area) resu lts in an equal amount saved' in the apartments.

This derived baseline profile is adjusted for seasonal variations using the factors presented for a single family home. The resulting housing for the elderly seasonal domestic hot water profiles are presented in Figure 5-10 for an apartment

occupied by one person; these profiles are reduced by one-half.

Regional correction factors that take into account differences in well water temperature. are provided in Table 5-5. The appropriate factor for the region being

studied is applied to each of the seasonal domestic hot water profiles.

Projections for Years 1986 and 2000

Reductions in home appliance energy use is anticipated in the coming years for a number of factors, the most important of which includes increased cost of energy, government mandated appliance efficiency standards and decreased family size. Consequently, energy reduction factors are established in each of the desig­nated categories of energy use for the study year 1986 and the year 2000. The ener­gy reduction factors are applied to the 1977 base year load profiles previously presented for each of the residential housing types.

Baseload Projections In the baseload area, further energy reductions due to changes in patterns of

use to conserve energy would not have a very significant impact over that already achieved since the 1973 oil embargo. Significant reductions will, however, result

from government promulgated appliance efficiency standards.

Two sources of information are utilized in arriving at 1986 projected reduc­tions in baseload demand: A Brookhaven National Laboratory Study (Reference 5-14)

5-27

1.0 0.9

0.8 .J:: 3: 0.7 .:.t.

I OJ 0.6 V'>

:::l

>, 0.5 01 s... 0.4 OJ s::

I.JJ 0.3 0.2 0.1

0.8

.J:: 0.7

3: .:.t. 0.6 I

OJ V'> 0.5 :::l

i;l 0.4 s... OJ 0.3 s::

I.JJ

0.2

0.1

0.6 ..<:: 3: 0.5 .:.t..

I OJ V'> 0.4

:::l

i;l 0.3 s... OJ 0.2 s::

I.JJ 0.1

0.8 ..<:: 0.7 3: .:.t. 0.6 I OJ V'> 0.5 :::l

i;l 0.4 s... OJ 0.3 s::

I.JJ

0.2 0.1

Winter

Energy Used = 1.39 kWh/Day

Energy Used 11.3 kWh/Day

Summer

Energy Used = 7.8 kWh/Day

Spri ng

Energy Used = 10.4 kWh/Day

Time of Day

Figure 5-10. Electrical Load Profiles - Domestic Hot Water Housing for the Elderly - Apartment for Two

5-28

•

•

•

•

•

•

•

and DOE Appliance Efficiency Targets issued in the Federal Register (Reference 5-15). Each of these studies used 1972 as their base year and projected reductions to the year 1985. As indicated in Table 5-12 BNL projects a 9.4% reduction, while DOE efficiency targets result in a 23.4% overall change. Averaging these reductions and

dividing by the 13 year interval (i.e., 1972 to 1985) results in a 1-1/4% reduction per year. The yearly 1-1/4% for the period 1977 to 1986 provides an 11-1/4% overall reduction applied to the 1977 baseload profiles.

As an aid in projecting the additional reduction to the year 2000, data from

a RAND Corp. research study was used (Reference 5-7). In this report an energy re­duction of 2.6% for the 10 year period 1990 to 2000 is estimated based on continued

improvement in appliance standards. Therefore, a 1/4% reduction per year is applied to the 1986 demand up to the year 2000.

Cooking, Clothes Drying and Domestic Hot water Projections Reductions in energy use for cooking, clothes drying and domestic hot water

based on DOE efficiency targets for 1985 represent 3%, 4% and 15% respectively,

• starting from base year 1972. Average family size reduction, conservation practices as well as more widespread use of the energy efficient micro-wave ovens (estimated

annual use 190 kWh - Reference 5-16) will further reduce energy requirements in these household areas by 1986. Yearly reductions of 1% for cooking, 1/2% for clothes drying and 1-1/4% for domestic hot water will be applied to the appropriate

1977 base year profiles to obtain 1986 energy use.

•

•

As in the case of baseload demand, a further 1/4% per year reduction in ener­

gy from 1986 to year 2000 is also anticipated for cooking, clothes drying and domes­tic hot water.

Summary of Electrical Demand Projections for 1986 and 2000 Table 5-3 summarizes the yearly and total reductions projected to 1986 and

2000. By year 1986, baseload and domestic hot water demand will each be reduced

from 1977 levels by a total of 11-1/4%, with the combined cooking and clothes drying demand down by 6-3/4%. For the housing for the elderly, where a single profile de­fines baseload as well as cooking and clothes drying, a 11-1/4% reduction will be applied as a 1986 projection. Elevator consumption will also be reduced by the same

11-1/4%.

5-29

• Table 5-12

Baseload Electrical Demand Projections

Demand in kWh • 1972 1985 1985

1--

Base BNL DOE Appl. End Use Device Year Study % Eff. Targets %

Lighting 908 908 0 908 0 Dishwasher 381 337 11. 5 302 5 Washing Machine 103 103 0 103 0 Color TV 615 439 28.7 215 65 • B&W TV 351 117 66.7 288 35 Freezer 1406 1318 6.3 1012 28 Refrigerator l318 l318 0 891 39 Misc. Small Appl. 732 732 0 732 0

Totals 5814 5272 9.4 4451 23.4

•

• 5-30

•

•

•

•

•

5-1.

5-2.

References

General Electric, Regional Conceptual Design & Analysis Studies for Residen­tial Photovoltaic Systems, Report No. SAND 78-7039, January 1972.

Shepard, N. F., Jr., Results of Photovoltaic Residential Systems Analysis for MIT-Lincoln Laboratories, General Electric Co. Report PIR No. IM20-606, 25 May 1977.

5-3. Institute of Gas Technology, Application Analysis of Solar Total Energy to the Residential Sector, Quarterly Technical Status Report for the Period April 1 through June 30, 1977. Contract No. EG-47-C-04-3787 for Energy Re­search and Development Administration. Chicago: Institute of Gas Techno­logy, August 1977.

5-4. Gamze-Korobkin-Caloger, Inc., Appliance Use - Profiles Across Hours. Un-

5-5.

5-6.

5-7.

5-8.

5-9.

published Report (1976).

Arizona Public Service Co., Electric Class of Customer Study, (Unpublished Computer Runs). Phoenix, Arizona, Feb. 28 & March 2, 1979.

Water Information Center, Water Atlas of the United St~es, Port Washington, May 1973.

Dole, J. H., Energy Use and Conservation in the Residential Sector: A Re­gional Analysis. (Prepared For) National Science Foundation (Under Grant No.) R-1641-NSF. Santa Monica, CA: The Rand Corp., June 1975.

Union Electric Co., Average KWHR Use and Revenue per Customer by Type of Dwelling. Unpublished tabulatlon by Market Research Dept., March 6, 1918.

Arkansas Power & Light Co., Residential Study of Total-Electric Mobile Homes, Little Rock, Arkansas, Oct. 1971 through Sept. 1972.

5-10. James W. Coleman, Mobile Homes Are Not Very Mobile. Electrical World, Feb. 1, 1977.

5-11. American Gas Association, Ecube Applications Manual. Arlington, Virginia. December 1973.

5-12. Edison Electric Co. of New York, Load Characteristics of an All-Electric High-Rise Apartment Building. New York, N.Y., August 1967 through August 1968.

5-13. American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., ASHRAE Handbook & Product Directory 1976 Systems, New York; ASHRAE, 1976.

5-14. Lee, J., Future Residential and Commercial Demand in the Northeast, (Prepared For) Energy Research and Development Administration Under Contract No. E(30-1)-16, (Report No. BNL 50552.) Upton, New York: Brookhaven National Labora­tory, March 1976 .

5-31

5-15. Dept. of Energy, Final Energy Efficiency Improvement Target. Federal Regis­ter, April & October 1978.

5-16. Edison Electric Institute, Annual Energy Requirements of Electrical Household Appliances, EEI-PUB#75-61 Rev. (1977).

5-17. Samuels, G., et al, MIUS Systems Analysis - Initial Comparisons of Modular Sized Integrated Utillty Systems and Conventlonal Systems. Oak Rldge Na­tional Laboratory, ORNL/HUD/MIUS-6, June 1976.

5-18. Wolfer, B. M., et al, Prel iminary Design of a Basel ine MIUS. NASA LBJ Space Center, NASA TMX-58193, April 1977.

5-19. Hise, E. L., et al, Comparison of MIUS and Conventional Utility Systems for an Existing Development. Oak Ridge National Laboratory, June 1978.

5-20. David Sage Inc., Energy Use in New York City High Rise Housing (Prepared for Citizens for Clean Air, Inc. J. New York, N.Y., 1972.

5-21. New England Power Planning, Energy Consumption Profiles for Residential Ap­p 1 i ances (unpub 1 i shed Computer Runs). West Spr i ngfie 1 d, Mass., May 19}6 & Febru ary 1977.

5-22. Hittman Associates, Inc., Residential Energy Consumption Multi-Family Housing

•

•

Final Report. (Prepared under Contract No. H-1654 for HUD). Columbia, Mary- • land, HUD-HAl-4, June 1974.

5-23. Blumst, W., Appliance Energy Consumption, Electrical World, August 1, 1977.

•

• 5-32

•

•

•

•

•

SECTION 6 SPACE CONDITIONING lOADS

Summary

In order to realistically evaluate the performance characteristics of a resi­dential photovoltaic system, detailed analyses of building heating and cooling energy demands are required to determine hourly load profiles which the solar system must supply. This section presents the techniques utilized in generating these profiles.

Space heating and cooling energy requirements are determined for each of the RlC types identified in Section 4. Building thermal characteristics, in terms of conductive heat transfer paths between the conditioned spaces and ambient, are modeled and input to GE's Building Thermal Transient load (BTTl) program along with hourly weather data and building usage schedules. The hourly solar radiation and meteorological data used is TMY data for each of the sites. Altogether, thirteen weather sites in twelve various climatic regions of the Continental U.S. are iden­tified in this study. For each site, building loads are generated for the RlC con­figuration based on building type popularity in that region. Figure 6-1 shows the regional designation of building types for which load analyses are made:

Figure 6-1. Sunbelt Single Family and Townhouse

6-1

D.C .

Figures 6-2 thru 6-6 present the annual space conditioning loads as functions of heating and cooling degree days for each RlC type. The heating and cooling degree days are based on a reference temperature of 18.30C (650 F). The figures show that

building loads, in general, are. linearly related to temperature degree-days. The slope of the relationship is approximately equal to the adjusted conductance area product (UA) of the building, w~ich is the sum of conduction UA, solar heat gain,

infiltration and internal heat generation rates.

The hour-bY-hour load profiles from the output of the BTTl code are written

and stored on magnetic tapes along with solar radiation and weather data. These tapes are input to the photovoltaic and thermal system simulation codes for system

performance analyses and trade-off studies purposes. The results are discussed in

Section 11.

Analytical Technique

•

•

The Building Transient Thermal loads (BTTl) program, a computer code developed •

by General Electric, is used to determine building heating and cooling energy demands

for the photovoltaic system. BTTl is a Fortran computer code that calculates heat­ing/cooling energy demands as a function of time for a structure which is defined by program input. The primary advantages of BTTl as an energy analyzer are that it uses

actual (not statistical or worst case) weather data on magnetic tape; it includes the effects of thermal capacitance (or inertia) of structural elements on thermal load

calculations; it simulates multi-zoned buildings; and it accommodates varying build-ing usage schedules and setbacks.

BTTl uses a simple finite difference mathematical technique to calculate time­varying temperature profiles of elements of a thermal model for a building. The

building is divided by the user into a finite number of "nodes," each of which repre-sents a physical entity of the building (such as a layer of a wall) and is assumed

spatially isothermal. Input consists of internode thermal couplings (conduction,

convection and radiation), active node thermal capacitances and initial temperatures, boundary conditions (typically heat source values and boundary temperatures), in-

•

ternal heat gains, and run control parameters. Each building temperature controlled

zone is simulated as a semi-active node. Zone temperature is allowed to float just •

like an active node as long as the temperature is within a user specified control

6-2

Q) , w

•

20,000 + i I

~ I ~ i" ~15,000 T ~ I ~ , r.l I <==1 i ~ 1 ~ 10,000 I ;:J I ::r: t

~ ;z; a

'" ;;'j 5,000

'"

I

o

•

REGIONS

1. BOSTON 2. WASHINGTON, D.C. 3, CHARLESTON 4. MIAMI S. BISMARCK 6, MADISON 7~ OMAHA 8. FT. WORTH 9. NASHVILLE

10. PHOENIX 11. ALBUQUERQUE 12. SEATTLE 13. SANTA MARIA

013

1000 2000 3000

HEATING DEGP£E DAYS (BASED ON lS.30C)

•

20,00

or--. .c 315 ,00

<==1

~ r.l <==1 •

~ 10,OOJ ...:l , a o u ...:l

~ o '" ;;'j 5,00

'" 13

2R 12

- -,.--4000 5000 o 500

FIGURE 6-2 SEASONAL SINGLE FAMILY RESIDENCE SPACE CONDITIONING LOADS

•

1000 1500

COOLING DEGREE DAYS (BASED ON lS.30C)

•

2000

~ .c ~

~

~ «l Cl ~ I ..,. c.!l z H H ~ «l ;;::

....:l -0: Z 0 (f)

-0: w (f)

60,000 t REGIONS

1. BOSTON 2. WASHINGTON. D.C. 3. CHARLESTON 4. MIAMI

50~000 r s. BISMARCK 6. MADISON ~ .c 7. OMAHA ~ a. FT. WORTH 9. NASHVILLE ~

40,000 t 10. PHOENIX NORTHERN ~ 11. ALBUQUERQUE 12. SEATTLE 13. SANTA MARIA .

30,000 + I

20,000 1 10,000

I' '.:) C!. j -+-----~--__t_---_+-

1000 2000 3000 4000

HEATING DEGREE DAYS (BASED ON 18.30C)

«l ~

c.!l Z H ....:l 0 0 '-' ....:l -0: Z 0 (f)

~ «l (f)

5000

FIGURE 6-3

50,00

40,00

30,00

20,00

10,00

/ "810

o I ~~ -+ -----1-------;---------;---500 1000 1500 2000

COOLING DEGREE DAYS (BASED ON 18.30C)

SEASONAL MULTI-FAMILY ATTACHED RESIDENCE SPACE CONDITIONING LOADS

• • • • •

•

60,000

50,000t

40,000 t ~ ..c: ~

U)

"" ~

! ;Z; , ~ U1

'" 30,000 t Q

Cl ;z; H H .,,;

'" i ::r;

....:t I .,,; 20,000 -!-z

0 , I W I .,,;

I '" Ul

10,0004.

• •

REGIONS

1. BOSTON 2. WASHINGTON, D.C. 3. CHARLESTON 4. MIAMI ~ ..c: 5. BISMARCK 6. MADISON

~

7. OMAHA U)

a. FT. WORTH A

~ 9. NASHVILLE 10. PHOENIX '" A 11. ALBUQUERQUE

Cl 12. SEATTLE z 13. SANTA MARIA H

....:t 0 0 U

....:t .,,; z 0 Ul .,,; 1>l Ul

./

10 ···fi?:l:J..:.'-···B)-1---·~---.----i----- .. --.------.--+--

1000 2000 3000 4000 5000

HEATING DEGREE DAYS (BASED ON 18. 3°e)

FIGURE 6-4

I 100,000 t

I I

80,000

60,000

40,000

20,000

• •

7

-~-+-------t-------+----:2::-0~--500 1000 1500

COOLING DEGREE DAYS (BASED ON 18.30 e)

SEASONAL GARDEN APARTHENT SPACE CONDITIONING LOADS

20 r-.

~ '--'

t=l

~ 15 0\ r>l I t=l 0\

c.!J

~ ~ 10 iII

~ z 0 {f]

-0:: 5 r>l {f]

o

•

20 r-.

~ '--'

t=l

~ 15

r>l t=l

c.!J :z; H H 0 10 0 u

~ z 0 {f]

-0:: 5 t NORl'HERN r>l {f]

7

013 1----. ___ -'-_ L---__ --''-_____ ........ ____ -' o Ii.

o 1000 2000 3000 4000 5000 o 500 1000 1500 HEAl'ING DEGREE DAYS (BASED ON 18.3 DC)

COOLING DEGREE DAYS

Figure 6-5 Seasonal Mobile Kame Space Conditioning Loads • • •

2000

•

•

5

~

~ 4

0 0 rl '-'

,:::,

~ 3

0) oe1 , ,:::, ....., c.!J Z H H ~ r.q 2 ::r: >-" ~ Z 0

'" ~ oe1

1

'" SUNBELT

4

o 1000

•

2000 3000

HEATING DEGREE DAYS (BASED ON 18.3 OC)

NORTHERN

4000

•

~

~ '-'

o

~ r.q o c.!J Z H >-" 8 u

~ o

1. 25

1.00

.75

.50

~ .25 r-'l

'"

•

NORTHERN

4, l·

°1~· ______ ~ ______ ~ ______ ~ ______ J-__ __

5000 o 500 1000 1500 2000

COOLING DEGREE DAYS

Figure 6-6

Seasonal Housing for the Elderly Space Conditioning Loads

•

band. When the temperature reaches a limit of this band, the program applies heat­ing/cooling as required to zone nodes to maintain the temperature within the limits.

The amount of energy thus required is integrated over time and is output as zone thermal demand in hourly, daily, and/or monthly formats.

A summary of the program capabilities includes: • Up to 10 zones of independent temperature control in any modeled building

•

•

•

•

•

•

•

Up to 25 planar surfaces enclosing the total building

Up to 50 nodes total ( ac t i ve, zone, and boundary)

Up to 100 conduction couplings

Up to 50 radiation couplings Up to 12 shading factors per year for each exposed external surface

Variable zone test set temperatures (summer/winter, day/night, furnace/ air conditioner) Variable internal (schedule) loading as a function of weekday and time of day.

Building Characteristics and Modeling

The space heating and c061 ing energy demands of a building can be determined

by summation of conduction, convection and radiation heat gains/losses; solar heat gains through windows; internal heat generation due to people, electrical appli­ances, cooking and showers, etc.; and infiltration heat gains/losses through window and door openings, hour by hour. Thus it is important, within the limitation of the

computer code, to model every heat transfer path and characteristic as well as occu-pants I behavior to ensure realistic prediction of the building load requirements.

The thermal characteristics and configurations of various building elements

of the residential dwellings is input to the program. In developing a heat transfer

thermal model for each house, a node is assigned to every planar surface of the

house with one or more parallel heat transfer paths. Values of thermal capacitance, initial temperature, radiation and conduction couplings with adjacent nodes are

determined for the node to represent that physical entity of the building.

Most of the buildings except for the mobile homes and the housing for the

elderly are modeled with two independent temperature control zones: one for the

6-8

•

•

•

•

•

~ bedroom areas and one for the living, dining rooms and kitchen areas. The thermo­stat settings for each RLC type are summarized in Table 6-1.

•

•

•

•

Tab 1 e 6-1 Building Temperature Control Assumptions

Space Set Temperatures, of Set Back Temperatures, of

Residential Load Cond it i on- Living Living Center Type ing Mode Areas Bedroom Areas Bedroom

Single Family Heat i ng 68 63 63 63 Detached Cooling 78 78 78 78 Townhouses Apartments

Mobile Home Heating 68 68 63 63 Cooling 78 78 78 78

Housing for the Heating 70 70 70 70 Elderly Cooling 78 78 78 78

Each dwelling is assumed to be occupied by a family size as indicated in Table 3-3. The loads for the housing for the elderly are calculated for the total

building assuming an occupancy of 181 people. Table 6-2 summarizes the occupancy profile for each building type. The internal sensible and latent heat generated

Table 6-2

Occupancy Schedules for Each RLC

Residential Occupancy Load Load Center

Type Midnight to 8 A.M. 8 A.M. to 5 P.M. 5 P.M.

Single Family Detached 4 3 Townhouses (Per Un it) 4 3 Garden Apartments (Per Unit) 3 2 Mobile Homes 3 2

Midnight to 10 A.M. 10 A.M. to 4 P.M. 4 P.M.

Housing for the * 181 Elderly gO

(Total Building)

*Occupancy shifts between building zones within each time interval. 6-9

to Midnight

4

4

3

3

to Midnight

181

by occupants, lighting, cooking and miscellaneous appliances are derived from the hourly profiles of diversified electrical loads and cooking loads established in Section 5. Due to certain limitations of the code, the hourly internal heat pro­

files are modified and reduced to four usage periods per day as represented by the

profile in Figure 6-7 for a garden apartment unit. The latent portion of the load was estimated from any showers, boiling of water or other evaporative type processes occurring within the residence besides that due to human presence. The heat gene-

•

rated by operating a washer and dryer are not considered as part of heat gains in the ~

conditioning space as they are assumed to be located in the unheated equipment room.

The infiltration rate through window and door leakage is assumed to be a function of wind speed. Since air flows are due to changes in air-stream stati~ pressure, which, over the surfaces of buildings, are approximately proportional to

the square of wind speed, the following equation is used in calculating infiltration gain of the building:

Infiltratlon = 0.25 + 0.5 x (m/secl~~~f speed) 2 air change per hour

The building thermal model, internal heat generation profile and hourly wea­ther data are input to the BTTL program to calculate space conditioning loads in various climat:c regions.

Space Heating and Cooling Loads

Building heating and cooling energy needs are analyzed for all climatic re­

gions and the results are shown in Figures 6-2 through 6-6 earlier. All building

•

loads are in good correlation with heating and cooling temperature degree-days ... listed in Table 6-3 for the thirteen sites.

The straight line correlation is approximately equal to the overall UA of the building, with two exceptions. The buildings in the Santa Maria area show a lower heating energy demand than in other regions. This slight deviaiton is due to year­round moderate temperature, characteristic of the Southern California coastal climate.

The curves provide an estimate of the annual space conditioning loads for a • similar type building in a different heating or cooling degree-day climate. The monthly loads are tabulated in Tables 6-4 through 6-13 for completeness.

6-10

•

•

•

•

•

1.0

.l!

~ 8 , T ,

z o

>­« f5 ~6 :z IJ.J

'" >-;:i .4 :I:

..J « :z 0:: IJ.J

!z .2

BASELOAD, HOT WATER AND COOKING LOADS

SENSIBLE -j

'1 ____ I

LATENT c-

I r--I...- __ . ______ ... __ J

o _::-=+"-"+ ~.,,_ -t----+ --+---1-_.-1._- --+---..f--. I I '=-1

M 2 4 6 8 10 NOON 14 16 18 20 22 N

Figure 6~7 Sample of Internal Loads for Garden Apartment (Per Unit)

Table 6-3 TMY Heating and Cooling Degree-Days for the Study Sites

Heating* Cooling* Region Deqree Days Degree Days

Boston 3190 389 Washington, D.C . 2676 605 Charleston 1218 1116 Mi ami 102 2249 Bismarch 4994 275 Madison 4128 304 Omaha 3314 628 Ft. Worth 1307 1360 Nashville 1980 869 Phoenix 767 2026 Albuquerque 2448 699 Seattle 2927 59 Santa Maria 1680 51

*Based on 18.30 C.

6-11

0"> I

I-' N

SITE LOCA-nONS

MONTH

JANUARY .

FEBRUARY

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

NOVEMBER

DECEMBER

TOTAL

•

SANTA MARIA (kWh)

COOL-ING

110

104

90

38

38

1

100

91

171

222

238

196

1399

MIAMI (kWh)

HEAT- COOL-ING ING

294 75

129 91

51 989

45 1035

12 . 1351

8 1687

0 11:.14

0 1986

0 1923

3 1497

28 1191

109 140

679 13779

•

Table 6-4 Sunbelt Single Family Monthly Load Profiles

I PHOENIX FT.WORTH ALBUQUERQUE CHARLESTON NASHVILLE (kWh) (kWh) ( kWh) (kWh) ( kWh)

HEAT- COOL- HEAT- COOL- HEAT COOl- HEAT- COOL- HEAT- COOL- HEAT-ING ING ING- ING ING ING ING ING ING ING ING

52 28 414 13 992 0 1468 4 684 0 1354

11 32 208 14 566 2 1046 3 496 0 969

Q 77 76 6" 345 0 782 4 234 0 555

0 72 11 7 31 0 232 8 46 2 187

0 1358 0 732 1 17 60 30 2 7 31

0 2099 0 1604 0 710 0 1172 0 940 0

0 2637 0 2072 0 1098 0 1554 0 1385 0

0 2390 0 1949 0 913 0 1437 0 1227 0 I

0 1952 0 1110 0 28 3 1157 0 93 0

b 874 0 500 12 31 108 37 38 25 79

0 155 32 71 145 3 474 40 169 2 326

22 65 271 11 581 0 1091 7 426 0 1093

85 11739 1013 8089 2673 2802 5264 5453 2095 3680 4644

• • •

0> , I-' W

•

~ SITE LOCA-

MONTH TI~

JANUARV

FEBRUARY

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

NOVEMBER

! DECEMBER

TOTAL

OMAHA (kWh)

COOL- HEAT-ING . ING

0 2728

0 2111

0 1265

1 296

55 13

1002 0

1427 0

1410 0

392 25

18 259

4 1090

0 2225

4309 10012

• • Table 6-5

Northern Detached Single Family Monthly Load Profiles

. D.C. BOSTON MADISON (kWh) (kWh) (kWh)

COOL- HEAT- COOL- HEAT- COOL- HEAT-ING ING ING ING ING ING

0 1924 0 2439 0 3170

0 1553 0 1565 0 2472

0 887 0 1537 0 2009

12 255 0 613 0 637

52 33 11 288 23 192

539 0 60 32 60 9

1378 0 922 0 948 0

1205 0 801 0 662 0

128 1 343 0 11 33

18 117 13 246 0 434

7 663 0 960 0 1523

0 1441 0 2079 0 2578

3339 6874 2150 9759 1704 13057

• • BISMARCK SEATTLE

(kWh) ( kWh) COOL- HEAT- COOL- HEAT-

ING ING ING ING

0 3706 0 1550

0 2915 a 1013

0 2139 0 986

0 1136 0 538

3 298 6 247

170 31 0 33

847 0 342 0 .

432 1 278 0

11 240 181 0

0 821 0 382

0 2140 0 807

0 3582 0 1530

_",eo

1463 17009 807 7086

CJ) I ......

-l'>

SITE LOCA-nON

MONTH

JANUARY.

FEBRUARY

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

rlOVEMBER

DECEMBER

. TOTAL

•

OMAHA (kWh)

COOL- HEAT-ING ING

0 9591

0 7416

0 4443

0 993

122 76

3847 0

5353 0

5302 0

1471 63

71 823

23 3678

0 7746

16190 34830

Table 6-6 Northern 4 Unit Townhouse Monthly Load Profiles

D.C. BOSTON MADISON (kWh) (kWh) (kWh)

COOL- HEAT- COOL- HEAT- COOL~ HEAT-ING ING ING ING ING ING

0 6700 0 8647 0 11158

0 5390 0 5492 0 8697

0 3035 0 5414 0 7106

28 839 0 2114 0 2221

174 92 33 987 62 631

2045 0 192 88 192 22

5246 0 3536 0 3615 0

4575 0 3080 0 2515 0

488 3 1336 0 37 83

70 326 52 800 0 1415

26 2193 2 3282 0 5233

0 4905 0 7259 0 8961

12653 23482 8231 34085 6420 45528 -- -- -

• •

1 BISMARCK I SEATTLE i (kWh) I (kWh)

COOL- HEAT- I COOL- HEAT-ING ING , ING ING

0 13135 0 5423

0 10275 . 0 3481

0 7573 0 3393

0 4027 0 1824

1 1013 7 809

621 88 0 64

3126 0 1190 0

1530 1 1011 0

37 773 683 0

2 2752 0 1245

0 7435 0 2714

0 12588 0 5324

5317 59660 2890 24306

• •

O'l I ......

U1

•

""~ SITE , LOCA-":t:.l0NS

MONTH '"

JANUARY

FEBRUARY

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

NOVEMBER

DECEMBER

TOTAL

- -

• • Table 6-7

Southern 4 Unit Multiplex Monthly Load Profiles

SANTA MIAMI PHOENIX FT.WORTH ALBUQUERQUE MARIA

(kWh) (kWh) (kWh) ( kWh) ( kWh) COOl- HEAT-· C9~b- H1AQ- C?~b- ~~~T- ¥~2L- ~~~T- ¥22L- ~~~T-TNI': TNI':

100 153 406 9 12 391 7 2205 0 3737

176 9 647 0 23 66 0 1243 0 2515

396 0 4812 0 385 1 23 601 0 1567

541 0 5338 0 1206 0 189 0 33 87

735 0 6581 0 6343 0 4200 0 704 0

728 0 7785 0 8714 0 7767 0 4368 0

1563 0 8306 0 10266 0 8809 0 5653 0

1256 0 9119 0 9370 0 8402 0 4657 0

1000 0 8230 0 7244 0 4694 0 435 0

973 0 6553 0 3442 0 2199 0 156 79

481 0 4688 0 275 0 122 212 0 1123

279 76 491 2 21 479 0 1759 0 3412

8228 238 62634 11 47301 937 36413 6019 16005 12519

-- ----

• •

CHARLESTON NASHVILLE

(kWh) ( kWh) ~22L- ~~~T- 1~L- ~~~T-

0 1248 0 3323

3 822 0 2273

27 291 0 886

312 1 72 '130

912 0 469 0

6072 0 5221 0

7492 0 6933 0

6751 0 5961 0

5329 0 851 0

278 5 157 47

71 289 0 910

0 1067 0 3294

27247 3725 19665 10863

0> I

I--' 0>

~SITE LOCA-nON

MONTH c~

JANUARY

FEBRUARY

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

NOVEMBER

DECEMBER

TOTAL

•

'.

Table 6-8 Northern 8 Unit Garden Apartment Monthly Load Profiles

OMAHA D.C. BOSTON MADISON BISMARCK (kWh) (kWh) (kWh) (kWh) (kWh)

COOL- HEAT- COOL- HEAT- COOL- HEAT- COOL- HEAT- COOL- HEAT-ING ING ING ING ING ING ING ING ING ING

0 7964 0 4672 0 7266 0 9679 0 12041

0 5892 0 3605 0 3946 0 7130 0 8857

0 2899 0 1327 '0 3821 0 5531 0 5950

6 207 141 138 0 785 0 1083 0 2457

385 0 288 0 60 420 121 197 3 410

5880 0 3532 0 674 0 577 0 1112 0

7707 '0 7713 0 5675 0 5717 0 4832 0

7638 0 6751 0 4899 0 4132 0 2413 0

1863 0 713 0 1791 0 38 0 339 0

173 122 153 10 138 240 0 352 1103 0

13 2027 0 850 0 2035 0 3587 0 5633

0 6220 0 2934 0 5780 0 7205 0 11478

23665 25333 19290 13535 13237 24293 10585 34764 8387 48269

• • •

SEATTLE (kWh)

COOL- HEAT-ING ING

0 3470

0 . 1717

0 1767

0 438

13 241

5 0

2203 0

2137 0

724 0

5 233

0 989

0 3638

5088 12492

•

ct> I

I--'

"

• SITE LOCA-nONS

MONTH .

JANUARY

. FEBRUARY

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

NOVEMBER

DECEMBER

TOTAL

• SANTA MARIA

( kWh) COOL- HEAT-

ING ING

716 0

1084 0

,1243 0

1196 0

462 0

274 0

1654 0

1398 0

1373 0

3093 0 . 2218 0

1532 0

16243 0

• Table 6-9

Sunbelt 8 Unit Garden Apartment Monthly Load Profiles

MIAMI PHOENIX FT.WORTH ALBUQUERQUE ( kWh) (kWh) ( kWh) (kWh)

COOL-HEAT- COOL-HEAT- COOL-HEAT- COOL- HEAT-ING ING ING ING ING ING ING ING

2185 0 182 110 49 1497 0 2296

2462 0 331 0 18 810 0 1603

8014 0 1216 0 ·59 367 0 1143

8155 0 2214 0 410 0 0 35

8795 0 7738 0 5621 0 606 0

10389 0 10757 0 9904 0 5367 0

10974 0 12832 0 11190 0 7151 0

11649 0 11782 0 10780 0 6038 0 . 11018 0 9354 0 6350 0 243 0

10433 0 6569 0 4476 0 757 38

8636 0 1520 0 604 0 0 291

2161 , 0 223 177 0 69 0 1912

94872 0 64716 287 49459 3844 20161 7317 ~

• • !

CHARLESTON NASHVILLE (kWh) ( kWh)

COOL- HEAT- COOL- HEAT-ING ING ING ING

7 657 0 2534

32 322 0 1577

227 143 0 489

892 0 273 57

1220 0 620 0

8058 0 6886 0

9950 0 9096 0

9215 0 8116 0

7462 0 1290 0

1131 0 774 0

547 109 0 572

0 470 0 2491

38742 1701 27055 7720

'" I I-' co

~TE LOCA-nON

MONTH '~

JANUARY

FEBRUARY

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

NOVEMBER

DECEMBER

TOTAL

•

OMAHA (kWh)

COOL- HEAT-ING ING

0 3094

0 2419

0 1567

0 478

23 64

744 0

1070 0

1065 0

270 85

2 470

0 1394

0 2540

3173 12111

•

Table 6-10 Northern Mobile Home Monthly Load Profiles

D. C. BOSTON MADISON (kWh) (kWh) (kWh)

COOL- HEAT- COOL- HEAT- COOL- HEAT-ING ING ING ING ING ING

0 2215 0 2632 0 3492

0 1809 0 1793 0 2758.

0 1195 0 1807 0 2386

7 445 0 825 0 868

42 108 8 411 16 336

398 2 45 85 42 43

1040 0 662 0 683 0

. 921 0 589 0 484 0

87 15 205 7 5 119

0 281 8 416 0 659

0 925 0 1185 0 1783

0 1722 0 2297 0 2793

2495 8717 517 11458 1229 15237

.. ,

•

BISMARCK SEATTLE (kWh) (kWh)

COOL- HEAT- COOL- HEAT-ING ING ING ING

0 3999 0 1699

0 3251 0 1195

I 0 2486 0 1233 I I 0 1397 0 798

0 466 2 445 ,

116 92 , 0 118 ,

595 0 222 0

339 10 I 178 0

0 402 85 3

0 1091 0 554

0 2396 0 987

0 3854 0 1651

1050 19442 486 8682

• •

0\ I

I---' <0

I

•

MONTH

JANUARY

FEBRUARY

MARCH

APRIL

MAY

JUNE

JULY

AUGUST

SEPTEMBER

OCTOBER

NOVEMBER

DECEMBER

TOTAL

SITE LOCA-nONS

•

SANTA MARIA (kWh)

~OOL- HEAT-ING ING

4 301

12 154

7 69

18 50

42 11

1 3

106 0

92 0

139 0

83 2

40 54

15 195

560 840

• Table 6-11

Sunbelt Mobile Home Monthly Load Profiles

MIAMI PHOENIX FT. WORTH ALBUQUERQUE (kWh) (kWh) ( kWh) (kWh)

COOL- HEAT- COOL- HEAT- COOL- HEAT COOL- HEAT-ING ING ING ING ING ING ING ING

43 64 0 503 0 1130 0 . 1693

58 37 1 365 0 751 0 1307

793 0 18 162 0 551 0 1042

943 0 89 36 15 73 0 368

1238 0 1206 0 712 7 46 106

1522 0 1878 0 1457 0 721 0

1645 0 2348 0 1865 o 1033 0

1807 0 2146 0 1754 0 852 0

1768 0 1731 0 969 0 30 9

1275 0 646 0 355 38 0 263

862 0 0 103 6 366 0 911

72 81 0 572 0 977 0 1605

12027 182 0063 1741 17133 3892 I 26B? 7303

• •

CHARLESTON NASHVILLE (kWh) (kWh)

COOL7" HEAT- COOL- HEAT-ItlG ING ING ING !

I 0 792 o . 1469 I

I ,

0 676 0 1160 I

0 379 0 769

14 104 4 303

83 5 31 61

1061 0 907 0

1423 0 1301 0

1327 0 1157 0

1057 0 141 2

27 107 13 237

9 391 0 687

0 756 0 1483

I flOnl 1211 3553 6173

Table 6-12 Northern Housing for the Elderly Monthly Load Profiles

CMAHA DC BOSTON MADISON BISMARK SEATTLE (kWh) (kWh) (kWh) (kWh) (kWh) (kWh)

COOLING HEATING COOLING HEATING COOLING HEATING COOLING HEATING COOLING HEATING COOLING HEATING

JANUARY 0 95708 0 53803 0 87712 0 110898 0 138769 0 33157

FEBRUARY 0 72544· 0 42073 0 49783 0 86945 0 104092 0 18946

MARCH 0 36724 0 15065 0 47878 0 69891 0 72615 0 20452

APRIL 592 1288 1090 986 I 0 9197 0 12459 0 27748 0 6995 Q) I

N MAY 17273 34 1 9143 01 2861 0 2884 4179 956 940 1938 1781 1979

JUNE 98207 o I 69461 0 18823 0 19719 0 29160 0 3025 0

JULY 116477 0 j 14877 0 96034 0 97324 0 82604 0 53334 0

AUGUST 117130 0 104263 0 81785 0 73503 0 48200 0 49234 0

SEPTEMBER 35091 0 24600 0 42327 0 9178 0 4671 998 29640 0

OCTOBER 5632 1520 7069 187 2707 2196 1054 3989 625 11290 1137 3638

NOVEMBER 200 24120 444 9077 117 24486 158 39104 0 64353 0 10466

OECEi·mm 0 74285 I 0 31478 I 0 68113 0 76702 0 129377 0 34119 -~--.---

TOTAL 390601 306223 330947 152670 244654 292249 205115 400944 166199 551180 138150 129752

• • • • •

• • • • • Table 6-13

Sunbelt Housing for the Elderly Monthly Load Profiles

'-,---._.--- -

SANTA M I . -•.. --.---~- .- --,--

~RIA MIAMI PHOENIX FT. WORTH ALBUQUERQUE CHARLESTON NASHVILLE ) (kWh) (kWh) (kWh) (kWh) (kWh) (kWh) HEAT- COOL- HEAT- COOL- HEAT- COOL- HEAT- COOL- HEAT- COOl- HEAT- COOL- HEAT-ING ING ING ING ING ING ING ING ING ING ING ING ING

JANUARY 12026 0 21455 12 5090 3028 466 16483 0 33598 874 8050 0 26002

FEBRUARY 13312 0 25663 0 6642 840 640 8911 69 24773 373 5412 0 17753

MARCH 17610 0 99097 0 15992 0 1487 4506 609 16540 3838 2379 38 5876

APRIL 18943 0 I

101031 0 29631 0 7651 0 1672 107 13307 0 3161 281 0'1 I I MAY 24367 N ....... 0 124760 0 117835 0 92391 0 19399 0 32356 0 21453 0

JUNE 20867 0 145908 0 143333 0 140406 0 91342 0 124588 0 108521 0

.JULY 42097 0 153268 0 167816 0 152275 0 106347 0 143185 0 130783 0

AUGUST 40435 0 161487 0 156425 0 150100 0 95511 0 133700 0 119382 0

SEPTEMBER 39418 0 153451 0 131164 0 99356 0 19287 0 114144 0 32124 0

OCTOBER 35138 0 126012 0 68345 0 53405 0 13240 117 15187 0 13011 158

NOVEMBER 23824 0 96702 0 16616 0 8087 890 1067 8879 8044 1170 1069 5170

. ~:~~~!~-13::::: 0 22241 0 7299 2997 298 11692 3 31020 1435 6172 0 23713

0 1231075 12 866187 6865 706562 42483 48546 . 115034 591031 23183 429543 78952

l ... •

The total space conditioning loads are summarized in another format as shown in Figure 6-8. The figure shows the range of heating and cooling loads for each RLC type over all the thirteen sites. In addition, the Bo~ton and Ft. Worth loads are indicated within the range as shown. The top comparison shows the general seasonal load decrease as units are combined into townhouse and apartment. The mobile home loads are shown significantly higher due to the different construction characteristics of this building.

The middle comparison on the figure is in terms of seasonal load per unit floor area. The bottom comparison is the range of annual space conditioning loads. It is noted that the bottom comparison is not the sum of the ranges shown in the middle comparison, but the range of the total heating and cooling loads for all the sites. The figure provides an overall evaluation of the space conditioning load ranges expected for the different RLC types.

6-22

•

•

•

•

•

• N 20000

I-u.. ....... 15000 • . .c 3. ~

... 0

10000 ~

« 0 5000 ....I

0

28

• 15 .c 3' .><:

10 ... .0 « 5 0

....I

0

N 20 I-u.. ....... • .c 15 :3

~

... 10 0 « 0 ....I 5

/0

•

SEASONAL LOAD PER FAMlLYUNIT

H c C H

C

i:!1 0 El , 0 H I

0 i ! I

, , 0

, EJ ~(!1 'G I c: f71

; - '-----' (.) i

SFRD SFRA GA

C

0

, El I

KEY SFRD-SINGLE FAMILY RESIDENCE

DETACHED SFRA-SINGLE FAMILY RESIDENCE

ATTACHED GA-GARDEN APARTMENT MH-MOBILE HOME H/C-HEATING/COOLING EI -BOSTON LOADS· o -FT. WORTH LOADS

El

C iI iC~

0 I n 18, ~ ';' !

MH ELD. APT,

SEASONAL LOAD PER UNIT FLOOR AREA H

c C El C H C C H

0 H 0 II 0 El 0 El 0~ El 0 El 0 [;] (.') Lfu (.) [;] r.] r.1!

SFRD SFRA GA MH ELD. APT.

ANNUAL LOAD PER UNIT F.LOOR AREA

q,

6 B ~ G ~ El

SFRD. SFRA GA MH ELD. APT,

Figure 6-8

Range of Building Heating and Cooling Loads 6-23

•

•

•

•

•

SECTION 7 UTILITY PRACTICE FOR RESIDENTIAL SERVICE

Summary

This section contains the results of a study to determine utility practices in providing residential electri~al service. Knowledge of utility practices is necessary to serve as a guide in establishing residential load center groupings, and to insure development of conceptual designs that are compatible with utility equip­ment and practices. This investigation includes a literature review, discussions with appropriate General Electric Product Departments, and telephone contact with a number of utilities to obtain information regarding their practices.

A utility power system has power flows from the generating station to a switching substation and then over high voltage transmission lines (e.g., 345 kV) to substations that reduce voltages to subtransmission levels (e.g., 115 kV). A second level of voltage transformation takes place at bulk power substations or small dis­tribution substations, which reduce voltages to the range of 4 to 35 kV. Primary feeder lines then deliver the electricity to local distribution transformers for re­duction to user levels, such as, 240/120V single phase or 480 Y/277 V three phase.

The two most common distribution systems in U.S. providing electrical service to residential areas are the pole mounted overhead system and the more recent under­ground buried cable system. Improvements in the familiar overhead systems have re­duced the clutter by elimination of the wooden crossarm, no longer needed with the introduction of three phase primary lines that are insulated, and replacement of the three secondary pole~mounted single phase wires with a single twisted triplex cable. Though considerably more expensive than overhead systems, underground systems have become commonplace in recent years. Elimination of unsightly poles winding through developments, as well as removing electrical power lines from exposure to damage from wind and ice storms are the prime advantages of the underground system. Regu­lations in many states require installation of an underground system for residential developments over a specified size (e.g., in Pennsylvania, over 5 homes). Technical advances in insulation since the 1960's have made possible the direct buried cable without the need for expensive concrete ducts. Pad mounted transformers, at the street level and transformers in underground vaults replace the familiar pole mounted units.

7-1

Both single and three phase distribution transformers are used in the resi­dential sector, with three phase primarily used in the larger multi-family building where three phase motors are used to operate pumps and elevators. Transformers are sized for use with a group of homes or dwelling units based on diversified peak de­mand. This demand is a function of the number of dwellings to be grouped as well as the connected load in each unit. Secondary and/or service cable size is based on maintaining voltage drop to within approximately 3%, in order to maintain an overall +5% or +5% and -3% state regulated requirement from substation to customer service entrance.

Typical practices in providing residential electrical service to residential housing of the types selected as models in this study were determined through dis­

cussion with utility distribution department personnel. A summary of these findings is presented in Table 7-1.

The basic elements of a utility transmission and distribution system are shown in Figure 7-1. Electrical power from the generating plant flows to the switch­ing stations which sectionaliz~ the system. The purpose of switching stations are to permit disconnect of only a section of the system in case of trouble (i.e., faults or short circuits) in a particular area, and to facilitate maintenance or new con­struction. Circuit breakers in the switching substation provide a means of cutting off any particular branch of the system. Power lines leaving the switching sub­stations are called transmission lines, which carry the highest voltage in the system. Transmission lines transmit power long distances and primarily serve to tie-together generating plants as well as deliver power to the next point in the system, the primary substation. A typical transmission voltage is 345 kV, with some systems in operation as low as 69 kV and others as high as 765 kV.

The high voltage transmission lines usually terminate at a primary substation outside a populated area. High voltage lines are not permitted in populated areas. Primary substations have also been called "high voltage substations", "transmission substations" and "bulk power substations". At primary substations the voltage is stepped down to subtransmission level, 115 kV for the example provided. This sub­transmission voltage is at an intermediate level between the transmission voltage and the next level designated as the distribution voltage. Substations generally

7-2

•

•

•

•

•

-...J I

W

• •

HOUSING TYPE

SINGLE FAMILY DETACHED

SINGLE FAHILY ATTACHED

MOBILE HOf4E

GARDEN APARTMENT BUILDING

HOUSING FOR THE ELDERLY -CONGREGATE LIVING (MID RISE BUILDING)

--

• •

• ()

II)

g

II

m

• Table 7-1

Utility Electrical Service Practices Related to Specific Housing Types

•

UTILITY PRACTICES IN PROVIDING SERVICE

4 TO 6 ALL-ELECTRIC HOMES SERVICED BY ONE 50 OR 75 KVA SINGLE PHASE TRANSFORMER

8 OR f40RE HOt1ES REQUIRING ONLY BASELOAD SERVICE AND CLOSELY SPACED CAN BE SERVED BY ONE TRANSFORMER

UNDERGROUND SERVICE MOST COMMON PRACTICE IN NEW DEVELOPMENTS

ENTIRE CLUSTER OF 4 TO 10 UNITS SERVICED BY ONE OR TWO SINGLE PHASE TRANSFORMERS. NUr,1BER OF TRANS FORMERS DEPENDENT ON CONNECTED LOAD

UNDERGROUrW SERVI CE FOR flEW CONSTRUCT! ON

SAf1E AS SINGLE FAMILY DETACHED

SAME AS SINGLE FAMILY ATTACHED GROUPING

•

THREE PHASE TRANSFORt1ER; SIZH1G. BASED ON NUt1BER OF APARTMENTS IN BUILDING AND CENTRAL FACILITIES REQUIREMENTS

I

...... I

-I'>

•

1L-fil~l / Generation Station

~ 115 KV ;,~ J~ _, 345 KV Tco"m""oo :y l°irl: g~H-ilO-r Transmission Line - \ I DL ~ A (:: '

""'LJ'r'tLf-&t. ...--.. zz: ~ ~ ~ 345 KV Transmission Switching Station

13 KV ~ Distri~ution lQ) r=AlI fIl Primary feeder 115 KV Bulk Power

Substation

345-115 KV Substation

115 KV

'.-"Iwita ktGlT "I :][:;Jnp " ..... ",.:n.... II,;"fL

Large Industrial Customer

~ _.~:n.~

23 KV kv ! Distribution .] [j]. (. Primary Feeder 115-23 KV Bulk Power

Substation Residential Customers

< 4.8 KV r=Jl] 4.8 KV Di stri but ion .... 1 .. rlt-=D7i s:"::t:"'r'-':i':"b-ut-j-O o-n---r-S-e-r-v-i-ce-s---r----.-I ~>

23-4.8 KV Primary Feeder Small Distribution ~ 16'n31 ~ ElL Substation Residential Customers

SOURCE: REfERENCE 7-2

Figure 7-1

Typical Utility Transmission and Distribution System

• • •

•. j

•

•

•

provide two other functions in addition to voltage transformation. These include switching or disconnecting parts of the system from each other and voltage control.

Power flows next from the primary sub~stations to either area bulk power sub­stations or small distribution substations which transform subtransmission voltages to distribution level voltages for use by industrial, commercJal andxesidential

. . .~

customers. The distribution system is that portion of the system'rthat del iv.ers the power to customers. It includes the primary circuit feeder lines as well as the di stribution substations that supply them; the local distribution transformers; and the secondary 1 i ne s that run to the customer service entrance from the 1 oc a 1 dis­tribution transformers. Primary feeder lines are usually run overhead, with voltage levels anywhere between 4 kV to 35 kV (3 phase, 4 wire) with the current trend to­wards the higher voltages. Pole mounted, underground, or pad mounted distribution transformers lower the voltage to the secondary system levels (i.e., customer use level) of 120/240 V. (1-phase, 3 wire); 208 Y/120 V. (3-phase, 4 wire); or 480 Y/227 V. (3-phase, 4 wire).

• The two most common primary feeder distribution system designs used in resi-

•

•

dential areas are the radial system and loop system. The radial feeder system (Figure 7-2) provides unidirectional flow to the customer through primary feeder lines that radiate out from the substation and have no other source of supply. Though this is the most economical system, a fault at any point in the line will cut off service to all further points on the feeder (nearest protective device will open section of line) until the fault is repaired. Faults near the substation will re­sult in removal of power from the entire line, thus cutting off service to a con­siderable number of customers until the fault is cleared. In the' loop system (Figure 7-3), the primary feeder line radiates out from thi returns to the sub-station forming a closed loop. The loop allows for supplying any segment of the load from either direchon. At some convenient point near the center of the loop, an automatic circuit switch is installed that is normally open. Each half of the loop operates like a radial feeder. When a fault occurs in either half of the loop, the faulty equipment is isol.ated and the circuit switch is closed for power to be fed to customers on the faulty loop section from the other normally functioning half of the loop. The loop system is extensively used in direct burial underground sys­tems and new overhead systems. It has proven very useful in underground systems where repair of faulty equipment could become a time consuming process.

7-5

• Customer Load

- ~ !1411) K leI

- -" S¢ "t",..,._: Substation

I I Primary Feeder

• Source: Ref. 7-2

Figure 7-2

Radial Feed - Distribution Feeder Circuit

•

II Aile ~ (" Substation

Switch

Primary Feeder • Source: Ref. 7-2

Figure 7-3

Loop - Distribution Feeder Circuit • 7-6

•

•

•

•

•

Residential Service

Information regarding utility practices in providing residential electric

service was obtained by reviewing pertinent literature, discussions with General

Electric product departments and telephone/letter contact with distribution system personnel in the following utility companies.

•

•

Georgia Power Co. Northeast Utilities

• Pennsylvania Power & Light Co.

• Alabama Power Co.

• Arizona Public Service Co.

Overhead and Underground Distribution Service The two most common distribution systems in the U.S. providing electrical

service to residential areas are the pole mounted overhead system and the under­ground buried cable system .

Overhead System -- In recent years, advanced techniques have led to pole mounted systems that are less obtrusive. Slimmer poles without crossarms now carry

insulated primary feeder lines that can be spaced closer together, reducing the cluttered look. The polyethylene jacketed primary lines provide insulation from

contact with trees, whereas the bare copper wires used previously resulted in numer­ous outages caused by contact with tree limbs. Though the polyethylene cover does

break down over prolonged contact (i.e., greater than a week) most tree limb con­tacts are for a very short interval. A new insulated secondary wire called the "triplex", which actually is three insulated wires entwined around each other, fur­

ther reduces the number of wires on the pole and the unsightly clutter .

Distribution transformers are placed on poles nearest the residences to be served. The transformers lower the voltage to the 120/240 V single phase required for the single family or small multi-family dwellings, or to the 480/227 V three

phase requirements of the large apartment buildings or commercial/industrial cus­tomers. Up to ten single family customers can be served from a single transformer

where the connected loads are low. Commercial and industrial customers, on the

other hand, are usually served by individual transformers .

7-7

, .

Underground System -- Though considerably more expensive than overhead 5YS-.

tems, underground systems have become commonplace in recent years. A major dis­

advantage associated with the underground system is the considerable time required

to repair d fault. However, most homes are now fed radial service lines (as op­

posed to the use of a secondary I ine that is tapped for each home) that feed power

to each home directly from the transformer. Should a fault occur in one service

line, it can be quickly insolated and power can continue to flow to the other homes

fed by the same transformer, whi Ie the fault is being r'epaired. • Two types of underground systems are presently in use. One involves the use

of a street level mounted transformer, called a "pad mount", and the other involves

use of a submet'sible transformer, i.e., transformer placed in an underground vault.

In both cases a primary feeder on an overhead system, running near the periphery of

a development is tapped and run underground to a series of transformers. Indi­

vidual radial service lines are then fed underground from the transformer secondary

taps directly to house service entrances. In certain cases underground secondaries

are used and service laterals tapped for each home. The direct radial service

lateral is the more popular in view of its advantage with regard to isolating fault.

for repair without disturbing service to other homes.

A typical underground distribution systern for a development containing

thirty-three single fwnily detached homes is presented in Figure 7-4. The primary

feeder is in a loop configuration. Six homes are fed from each transformer USing

radial Service I ines. Electrical service for a section of a mobile park is shown

in Figure 7-':J as another' dislributlon ser'/ice example. The primary feeder- in this

example is also in d loop configuration (the heavy dotted lines), with six mobile

homes fed from a single transformer. Secondaries are used to service each of three.

mobile homes. The secondary is tapped at a pedestal near the rear of each of the

thr'ee lots. Each pedestal contains a meter and a service connection for the mobile

horne.

Distribution Transformers and Service Cabling

Distribution Transformers -- Both single phase and three phase distribution

transformer's are used in the residential sector. Three phase service is primarily

lIsed in the larger multi-family buildings where three phase motors are required to

operate pumps and elevators. Installation of pad mounted transformers (i.e.,

7-8

•

•

•

•

•

•

,-----, • 8 r- __ ..I t.~~

~ r--------------+--------------~~ -<

I'

'--:1 , , .301 .. -~

TRANSFORMER

----------+--... --.--.. ---l

~~OL~ J .. ___ . ____ R..;.OA....;O:....W_AY_ o

OVERHEAD ELECTRIC LINE ~

SOURCE: PA. POWER & LIGHT

Figure 7-4

Typical Underground Distribution System for Residential Development

7-9

•

•

• Source: Georgia Power Co.

• Figure 7-5

Typical Mobile Home Park Underground Electrical Service

• 7-10

~ ground level transformer installation associated with underground cabling) is the most prevalent present day practice. Some pole mounted transformers are still installed where they do not violate state regulations and builders/owners do not

want to incur the additional cost of an underground installation.

•

•

•

•

Standard kVA ratings of single phase and three phase transformers are listed

in Tab 1 e 7 -2.

Table 7-2 Standard Transformers

SINGLE PHASE RATING-kVA

5 10 15 25 37.5 50 75

100 167

THREE PHASE RATING-kVA

75 112.5 150 225 300 500 750

1000 1500 2000 2500

Transformer primary side voltage is based on the primary feeder line voltage used in a particular area, which vary anywhere from 4 kV to 35 kV. Typical primary feeder voltages found in U.S. distribution systems are shown in Table 7-3.

Tab le 7-3 Typical Primary Feeder Three Phase Distribution Vo 1 tage

4160/2400 23860/13200 8320/4800 23900/13800 12470/7200 24940/14400 13200/7620 34500/19920 13800/7970

The trend in recent years has been towards the 25 kV and 35 k V c 1 as s of primary feeder voltages, particularly in areas where large scale development is anticipated .

7-11

Transformer secondary side voltages, presented in Table 7-4, are those de­

livered to meet the particular customer needs. The most common voltage is the

240/120 V. (single phase-3 wire system) supplied to the typical residence.

Tab le 7-4 Standard Service Line Voltages

SINGLE PHASE 240/120 V

277 V 480/240 V

THREE PHASE 208 Y /120 V

240 V 480 V

480 Y/277 V In selecting a transformer to provide power to a group of residential houses

or dwelling units in an apartment type building, utilities take into account diver­

sity. The electrical power required at any given time will be different for each residence in a particular grouping, even though they all may basically have the

same connected load. This diversity is accounted for in sizing a transformer. Uti 1 ities have developed diversity factors, presented in either graphical or tabu­

lar form, which indicate the anticipated peak demand for any given number of resi­dences having the same major group of electrical appliances. A typical example of

a graphical presentation of diversified peak demand is presented in Figure 7-6. This example is taken from GEls Distribution Data Book (GET-IOOSL) and is merely

provided for illustrative purposes, rather than as a definitive guide used by any particular utility.

The 1.5 kVA curve represents the calculated average residential consumer

with lighting, refrigeration and miscellaneous appliances, and the 2.4 kVA curve is the diversified demand for a consumer who also has an electric range and water

heater. Curves designated 4.8 kVA and 7.2 kVA represent homes with different de­grees of air conditioning, while the remaining plots correspond to homes with elec­tric heating. It should be noted that anticipated peak demand per home drops more abruptly with the first few homes added to a group and then tends to level off with

increased numbers of homes. Also, those homes with higher connected electrical loads do not initially drop off as rapidly and tend to level off more quickly.

This would indicate that for the all-electric home the impact of diversity on peak demand is not as great as where homes with only baseload requirements (i.e., lighting

7 -12

•

•

•

•

•

• -r

I KVA O.,ionolion, on Curve,·8o.ed on 16 He."'., • 40

~O

-1--

24.0KVA

.. 20 e 0 :r: "- 10 <t > !l

~-h r--- L ~~ h:--

..,. 14.4 y-vA

"-, -,....,.. -:-....... -- _. 9.6KVA -- - -; r-- --- -- .-

l.: 6

4

3

2

•

- - -- _. ~ . - 7.2 ,(VA ---:- --~ ~ -- -~ -r----: --

r--.."", -- _ ... _.

4 {l KVi\ I'-.... ~ -- I-- - --

" :---...,~ """""'"--- - ~ .. .. 2.4·KVA

~ ....... I 1.5KV.~

I I 4 .. 10 20 40 60 eo 100 500 1000 2000 GooO -

Numb"r 01 Hom •• I/.olimu"l Dc,'rrsHlcd D',mond per Hom. versu, Vo"Ou~ t/umber vi Itcmu

Source: Reference 7-3

• Figure 7-6

Peak Diversified Demand (Typical)

• 7-13

and miscellaneous appliances) are grouped. It should be pointed out once again, ... that these plots merely represent the kind of information which can be derived by utilities. Because of differences in living habits, geographical locations, tem-peratures, and summer and winter peak loads, these demands vary considerably.

Using the" appropriate diversity curve, a peak load can be established for sizing a transformer to be used to service a group of homes. The specific number of homes grouped is a function of their physical spacing and the associated voltage

drop considerations to be discussed in more detail below. 4It

Some utilities add a 20% factor to the total peak load, as determined above, in selecting an appropriate transformer rating. It is also important to note that utilities monitor transformer loading, and replace a unit with one of a higher rating only if peak loads consistently exceed 150 to 175% of nameplate rating. Winter peak load excesses are somewhat less critical than summer peak loads because of the beneficial effect of the colder temperatures on the outdoor transformers.

Service Cabling -- Increasingly, new hou~ing developments are being supplied by single phase underground distribution systems. The taps from primary feeders to the distribution transformer are operated line-to-multi grounded neutral, using a single, direct buried, solid, insulation cable (e.g. cross linked polyethylene) with bare, full-conductivity, concentric neutral. The primary feeder picks up transformers on either a radial or loop run and is nominally designed for 200 am­pere capacity. These cables are typically rated at 15 kV, 25 kV and 35 kV.

Secondary service in residential areas is the 240/120 V. single phase 3 wire type. The most common cable used is the three single conductor twisted triplex,

...

with aluminum conductors, polyethylene insulated. Past practice involved the run- ... ning of a secondary line off a distribution transformer and individual service cables tapped off this secondary to feed each home or building. Today most instal-lations involve running parallel circuits directly off the secondary taps of the transformer to each house. The wire size run to each home or building is selected to insure that the voltage drop under peak conditions will not exceed 3% of the standard nominal voltages. (Note: Permissible voltage drop from sUbstation to house entrance is normally prescribed by State regulation, with either +5% or +5%

• 7-14

• and -3% the usual requirements). Voltage drop plots, like the one presented in Figure 7-7 for single phase underground cable service, are used by utility distri­bution departments in selecting appropriate cable sizes.

Aluminum cables in the I/O and 4/0 and 350 MCM sizes are the most commonly used, The length of wire run and maximum load to be carried determines the wire

size selected to meet the voltage drop criteria. Typical maximum lengths of wire runs for I/O is on the order of 150 ft., 4/0 approximately 300 ft. and 350 MCM -600 ft. The peak load to be carried will, of course, determine the actual permis­sible maximum wire length. A larger wire size can be selected to run a longer dis-

... tance and still meet the voltage drop criteria; however, cost may then become a limiting factor.

•

•

•

Mobile home distribution cabling and installation practices are the same as for single family developments. However, sizing of cables are prescribed by regu­lations defined in "Standard for the Installation of Mobile Homes", paragraph 8.2, "Distributed System" (Ref. 7-7). This standard calls for a nominal 115/230 volt secondary distribution system with secondary and service lines sized as specified

in Table 7-5. As noted earlier, a dramatic drop in peak demand (see column DEMAND

Table 7-5 Demand Factors and Watts per Mobile Home Site (Minimum)

for Feeders and Service-Entrance Conductors

Number of Demand Factor Watts Per Mobile Mobile Homes (Percent) Home Site (Min.)

1 100 16,000 2 55 8,800 3 44 7,040 4 39 6,240 5 33 5,280 6 29 4,640 7-9 28 4,480 10-12 27 4,320 13-15 26 4,160 16-21 25 4,000 22-40 24 3,840 41-60 23 3,680 61 and over 22 3,520

SOURCE: REFERENCE 7-7

7 -15

168

156

132

120

~~~~----~--------------------~700 r;><' ~Vl B VCJ<PV

~~~~~~~--~--------------------------~650 fXDnUBLE •

350 MCM Ah~',\~ ___ --------------1600 3CT ~

~~~~§~~~~xm2~~~--------------------------l550 ~ x: ~----~~~~------------------------~--1500

fl ~~~----------------------------~ ~50

en I- 108 ....J o :>

o :z: ~ UJ o

60

~8

36

o o 100 200 300 ~OO 50:]

LENGTH - FEET

SOURCE: NORTHEAST UTILITIES

Figure 7-7

Direct Buried Single Phase Service Cable Selector Guide

7-16

200

o 600

•

•

•

•

•

FACTOR), takes place with the addition of a second mobile home, somewhat more with • the third, and then very sl ight additional changes due to diversity as more homes

are added to a group.

•

•

Transformer and Service Cabling Costs -- As discussed above, more residen­tial units can be added to a transformer if larger size service cabling is used (to

permit meeting voltage drop limitations). However, economic factors such as the cost of another transformer versus the additional cost of cabling and trenching for

longer distances become important considerations. To permit a determination of

what these cost trade-offs may be, approximate prices (1st Quarter 1979) for trans­formers and cabl ing was compi led and is presented in Table 7-6. It should be noted that prices are affected by quantity ordered, insulation class, particular sup­

plier, transportation costs, etc. The prices indicated are an average based on moderate purchase quantities, e.g., 10,000 ft. of cable.

Using the data found in Table 7-6, the economic trade-offs become immedi­

ately obvious. For example, take the case of adding an additional home some 200 ft. away from a 50 kVA transformer. Running a 200 ft. 4/0 cable (required based on connected load and voltage drop requirements) would cost $2,000 for the cable (ex­cluding trenching costs). On the other hand a new 50 kVA transformer would only

cost approximately $1,000, and a shorter length cable, possibly ev~n a smaller

size, could be used and trenching costs considerably reduced. The comparative costs of distribution transformers and cabling clearly highlight the reason for limiting the number of homes tied to a single transformer.

Utility Practices for Specific Housing Types

Typical utility practices in providing electrical service to housing of the

• types selected as models in the PV Residential Load Centers Study, was obtained through telephone discussion with personnel from the utilities cited earlier.

•

The following briefly delineates the general practice followed in providing electrical service to these specific housing types.

Single Family Detached

Usually four to six all-electric homes are connected to a single phase

7-17

'"..J I I-' O:l

•

Table 7-6

Typical Distribution Transformer and Service Cable Costs

(APPROX. PRICES - 1ST QUARTER 1979)*

PAD MOUNTED TRANSFORMERS

SINGLE PHASE THREE PHASE

KVA RATING

15 25 37.5 50 75

100 167

APPROX. COST ($) KVA RATING

870 75 900 112.5 980 150

1,060 225 1~390 300 1,570 500 2;150 750

1,000 1,500 2,000 2,500

SECONDARY (TRIPLEX) CABLE-ALUMINUM-XLP INSULATION

WIRE SIZE

#2 (WITH #2N) 1/0 ( 1/0 N) 2/0 ( 2/0 N) 3/0 ( 3/0 N) 4/0 ( 4/0 N)

250 MCM ( 3/0 N)· 350 MCM ( 3/0 N) 500 MCM ( 5/0 N)

APPROX. COST ($/FT)

4 6 7 8

10 12 15 21

*BASED ON INFORMAL TELEPHONE QUOTES FROM VARIOUS EQUIPMENT SUPPLIERS (E.G. GENERAL ELECTRIC, ANOCONDA, PIRELLI, ETC.) • • •

APPROX. COST ($)

2,750 3,'030 3,420 3,860 4,420 5,580 8,380 9,800

12,500 15,500 18,000

•

•

•

•

•

•

transformer using 50 or 75 kVA units. Up to eight or ten homes are connected to one . transformer if their relative physical locations permit and they are not all-electric.

Single Family Attached (Townhouse) The entire cluster (group of approximately 4 to 10 attached units) are serviced

by one or two single phase transformers, depending on the connected electrical load.

Since these residences are narrow and close together, service lines are short and thus do not present the kind of problem encountered with single family detached homes. A larger size transformer can, therefore, be used to handle a comparatively larger num­

ber of residences.

A pad-mounted unit is usually centrally located near the townhouse grouping and

service lines fed into a central panel on which are mounted all the meters for the group of homes. It is also possible to have one master meter where the units are

rented and the electrical charge included in the rental price by the owner of the complex. Where the townhouses are condominiums or individually owned, meters are

usually installed at each unit.

The plexes are provided electrical service in the same manner as the town-houses.

Garden Apartment Building

Service for garden apartment buildings is provided in the same manner as for the single family attached grouping.

Mobile Home

Mobile home parks use pad-mounted single phase transformers with secondary

underground feeder lines from which service cables are run underground to pedestals containing meters and connectors located near the back of each site. Usually, four to

six mobile homes are serviced by one transformer as in the case of the single family

all-electic homes. As many as 16 or as few as 4 homes have been serviced by one trans­

former, depending on the electrical equipment installed in the homes.

Housing for Elderly - Mid Rise Apartment Building

Three phase transformers are installed in view of the use of three phase motors for pumps and elevators. Sizing is a function of number of apartments and the central services.

7-19

The owner of the building may have the option of installing his own transformer, with the utility merely tying into the primary side of the transformer. Even if the utility provides the transformer, the owner usually provides connections from the

secondary taps to the switchgear located in the building. A single master meter or individual meters for each apartment are used based on how rental is fixed.

7-20

•

•

•

•

•

• 7.l.

~

7.2.

7.3.

• 7.4.

7.5.

7.6.

7.7.

•

•

•

References

General Electric, Electric Utility Systems and P.ractices. Electric Utility Engineering Operation Power Generation Sa1es Division, Schenectady, N.Y., GE 2-2587B, 1974.

Northeast Utilities Company, Underground and Overhead Distribution. Northeast Utilities Service Co., Hartford, Conn., 1974.

General Electric, Single-Phase, Pole Type Transformers. Distribution Trans­former Products Dept., Hickory, N.C., GEA-9332C, 1978.

General Electric, Single-Phase, Pad-Mount Transformers. Distribution Trans­former Products Dept., Hlckory, N.C., GEA-9349C, 1975.

General Electric, Compad Three-Phase, Pad-Mount Transformers. Distribution Transformer Products Dept., Hickory, N.C., GEA-5434.1, 1977.

General Electric, Distribution Data Book. Power Distribution Systems Engineer­ing Operation, Schenectady, N.Y., GET-lOOal, 1972.

National Fire Protection Association, Standards for the Installation of Mobile Homes. (Sponsored by Mfg. Housing Institute), Boston, Mass., NFPA 50lA, 1977.

7-21

• SECTION 8 PHOTOVOLTAIC/THERMAL SYSTEM DEFINITION

Summary

This section describes the solar energy systems selected for detailed perform­ance and economic analysis. The limited land availability at RLC sites restricts the systems to flat plate roof top array installations for all the RLC types except the mobile home park. All of the solar systems considered include photovoltaic genera-

~ tion, either alone or in combination with solar heating and cooling systems. When solar thermal energy collectors are considered, they are incorporated into side-by­side configurations with photovoltaic collectors, or are combined with the photo­voltaic elements into a single collector design. The following designations will be used throughout the following sections: PV designates photovoltaic arrays; T desig­nates thermal arrays; and PV/T designated combined arrays.

•

•

•

The systems selected for detailed performance analyses are listed in Table 8-1. The selection of these system types is based on the results presented in Ref­erence 8-1. Categories I, II and III refer to systems with PV-only arrays, systems with side-by-side PV and T arrays, and systems with combined PV/T arrays, respectively. Several system variations are identified, such as whether or not storage is used and alternatives for providing space heating by electrical or fossil energy.

Subsystem Definitions

The primary subsystem options considered in the study are summarized in Table 8-2 .

Solar Array In this residential solar energy study, emphasis is placed mostly on roof­

mounted solar collectors. Although collector fields could be conveniently located on or about areas adjacent to the residence, roof-mounted systems have been stressed for several reasons. First, the residential roof represents a conveniently available source of real estate which incurs little added expense for its use as a mounting surface. Second, the roof is close to the point of energy consumption and, there­fore, electrical and piping initial costs and operational losses are minimized .

8-1

Table B-1

Summary of Selected System Configurations

Solar Array Type

System Ident Installation Topology Config.

I (a) Roof Dispersed Shingle I (b) Roof Di spersed Shingle l(c) Roof Di spersed Shingle

PV - On ly I (d) Ground Centra 1 Flat

Side II (a) Roof Di spersed Flat By II (b) Roof Di spersed Flat

Side II (c) Roof Dispersed Flat II (d) Roof Oi spersed Flat

Combined III(a) Roof Dispersed Fl at PV/Thermal

.

Key

* SS Solar Supplemented

(X) I

N

• •

Type Storage Coo ling Heating

PV Only Battery HP HP PV Only Feedback Vapor·Compression Fossil PV Only Feedback HP HP

PV Only Feedback HP HP

Side-by-side Feedback HP SS/HP Side-by-side Feedback SS/Absorption* SS/Fossil Side-by-side Feedback SS/Rankine HP SS/HP Side-by-side Feedback flP HP

Combined Feedback fif' Para lle 1 SS/HP

• •

Hot Water Back Up

Electric Grid Foss il Grid Electric Grid

Electric Grid

SS/Elect. Grid SS/Fossil Grid SS/Elect. Grid SS/E lect. Grid

SS/Elect. _G~i~

•

•

•

•

•

•

COLLECTORS

Table 8-2

Subsystem Definitions

• PV Shingle (Block IV Generation)

• Arco-Solar Flat Plate Module

• Evacuated Tube Thermal Collector

• Flat Plate Combined PV/Thermal Collector

STORAGE • r

• Lead Acid Battery Type 75-88% Round Trip Efficiency

• Water for Thermal System

INVERTER

• Line Commutated 87% Efficiency

SPACE CONDITIONING EQUIPMENT (Separate Units/Control Per Living Unit)

• Weathertron Heat Pump

• Fossil Fired Furnace

• Absorption Chiller

• Rankine Driven Heat Pump

8-3

Third, the weatherproofing functiQn~ of the roof could be potentially satisfied by proper ly cjes i gned solar coll ectors. Thus, thei r app 1 i cat ion cou 1 d be cred i ted wi th any resulting savings in roofing materials and installation.

The collector modules considered as representative types in each of the cases included the GE Block IV shingle~odule for the PV-only systems, the GE evacuated tube thermal collector for the side-by-side configuration, and a generic liquid flat plate combined collector. A commercially available ARCO-SOLAR module is used for the ground-mounted mobile home park arr\l.Y.

Power Conversion

A line commutated inverter with maximum power tracking capability is used as the primary power conversion equipment. An average annual efficiency of 87% is as­sumed.

Storage

Lead-acid battery storage is considered for electrical energy. Other options, such as flywheels, are not considered in detail but general conclusions can be ob­tained by comparing their performance and cost potential with assumptions for the lead-acid battery used in the study. The results relative to on-site storage are based on these costs and performance assumptions so the specific form of storage could be changed.

For thermal systems, only sensible heat storage in a water medium is con­sidered.

Space Conditioning Equiement For the all electric cases, a heat pump is assumed for heating and cooling.

When a fossil fired heating system is used, a vapor compression unit is assumed for space cooling. For side-by-side PV/T systems, absorption chiller and Rankine driven heat pump options are considered.

System Configurations

The subsystems are combined into the system configurations discussed in the following sections.

8-4

•

•

•

•

•

•

•

•

•

•

PV-Only Systems System configurations identified for this category span a range of possi­

bilities for incorporating an all-PV roof into the residential energy system.

Configuration I(a) - PV-Only, Battery Direct Charge, All-Electric Load

This system takes the direct approach in applying photovoltaics to residential use.

As shown on the block diagram of Figure 8-1, dc power from the solar array or bat­

tery is converted to ac, which, in parallel with util ity power, satisfies the loads

of an all electric house. The parallel tie-in of the utility precludes the need for

elaborate peak load controls. This system has the capability for handling the large

load variation associated with residential use.

Configuration I(b) - PV-Only, No Storage, Sellback -- This configuration,

shown on Figure 8-2 has feedback to the utility line. This system is the easiest to

implement, has been shown to be the most economical approach in previous system

studies, and is also easiest to calculate from a performance standpoint. It is

therefore analyzed in all regions.

Configuration I(c) - PV-Only, No Storage, Fossil Heating, Vapor Compression

Cooling -- This configuration, shown on Figure 8-3, represents the application of a

PV-only system to a conventionally fossil heated residence with electrically-driven

vapor compression cooling. Significant performance differences with the all-electric,

PV-only system with power feedback [Configuration I(b)] may exist with respect to

satisfying the winter heating peak by fossil rather than electrical means.

Configuration I(d) - PV-Only, No Storage, Sellback -- Same as configuration

l(b) only ground mounted central array.

Side-By-Side PV and Thermal Systems

Side-by-side systems are designed so that different sections of the residence

roof produce different forms of solar conversion. One section may produce electricity

by PV conversion, a second section may collect low-temperature thermal energy for

space heating and domestic hot water production, and a third section may produce

hightemperature output for use in heat engines or absorption chillers. In general,

"side-by-side" means that each section provides a unique function rather than having

several functions produced by a single section as in the case of combined collectors.

Configuration ll:(a) - Side-by-Side, All-Electric, Solar Supplemented -- This

configuration, shown on Figure 8-4(a), uses a portion of the roof area for a thermal

8-5

UTILITY BACKUP

Figure 8-1 PV-Dnly Direct Battery Charge Schematic, I(a)

UTILITY BACKUP

MAX POWER TRACK

Figure 8-2 Schematic of All-Electric System With No Storage, I(b)

ELECTRIC/FOSSIL, NO STORAGE

FOSSIL FUEL

Figure 8-3

BACK-UP

Schematic of Electric/Fossil System Without Storage, I(c)

8-6

•

•

•

•

•

CD I

"

• • • • II (a) ALL ELECTRIC, SOLAR SUPPLEMENTED HEAT

BACK UP

II (bl ALL ELECTRIC, SOLAR DRIVEN COOLING II (,,) ELECTRIClFosSIL. SOLAR ABSORPTION COOLING

BACK UP BACK UP

PV I DC/AC ~ GENERAL ARRAY INVERT. LOADS

Figure 8-4

Schematics of Side-by-Side Systems Analyzed

•

collector whose output is used to supplement heqt pump output qnd hot water genera­tion.

The thermal collectors in this approach produce relatively low temperature outputs. Since the-thermal collectors can only meet space heating and hot water needs they are better applied to cooler climates where longer heating seasons would result in more effective utilization of the collectors.

Configuration II(b) - Side~by-Side. All Electric, Solar Driven Cooling -- In this concept, shown on Figure 8-4(b), the solar thermal collectors produce higher temperatures for either driving a Rankine engine or for supplementing heating and hot water. The schematic shows that the heat pump could be driven electrically or with appropriate clutching by the solar_driven Rankine engine. The equipment in­vestment dictates that cooling oepration must predominqte in order to achieve the necessary economic return and therefore warmer climates are selected for the analy­sis of this system.

Configuration II(c) ~ Side-by.,.Side, Electric/Fossil, Solar Driven -- This system, shown on Figure 8-4(c}, represents the fossil driven counterpart of the Rankine engine approach of lI(b). As shown on the schematic solar energy supple­ments fossil energy in meeting heating and cooling (absorption chiller) loads.

Configuration II(d}- Side-by-Side, Domestic Hot Water Solar System -- This system is similar to Configuration II(a); however, no solar space conditioning is included.

Combined PV/Thermal System

In these systems the solar collectors are designed to both generate elec­tricity and capture thermal energy. This is accomplished by placing solar cells in the optical path through the collector and providing a means for conducting away the thermal energy not converted to electricity. Since the thermal energy must be at a somewhat elevated temperature to be of use, there is usually a corresponding sacri­fice in PV output because of the solar cell's negative output dependency with tem­perature.

8-8

•

•

•

•

•

•

•

•

•

Configuration III(a) - Combined PV/T System, All Electric -- This system, as shown on Figure 8-5, uses the captured thermal energy to supplement space heating and hot water production. Since highly elevated temperatures would significantly

sacrifice PV output, no cooling versions of this concept were considered. For this reason, the regions for which this system was analyzed generally involve cooler

cl imates .

111(1) ALL ELECTRIC, SOLAR SUPPLEMENTED

PV I DClAC I GENER~i ARRAY I INVERT. I LOADS

THERMAL ARRAY - HEAT t--

PUMP

- HOT .t WATER -.

--- TES

Figure 8-5

Combined PV/Thermal System Schematic

8-9

References

8-1. Shepard, N.F., Landes, R. and Kornrumfp, W., Definition Study for Photovoltaic Residential Prototype System. Prepared for NASA Lewis Research Center, Docu­ment No. NAS CR135039, Philadelphia, PA: General Electric Co., September, 1976.

8-2. General Electric Co., Conceptual Design and System Analysis of Photovoltaic Systems; Final Report, Contract No. E4-76-C-04-368 for Sandia Laboratories, Report No. ALO-3686-14. Philadelphia: General Electric Co., March 1977.

•

8-3. General Electric Co., Develo~ment and Testing of Shingle-Type Solar Cell Modules, Final Report, Contract No. 9 4607 for Jet Propulslon Laboratorles, (Report • No.) DOE/JPL-954607-78/4. Philadelphia: General Electric Co., June 15, 1978.

•

•

• 8-10

• SECTION 9 PERFORMANCE AND ECONOMIC ANALYSIS METHODOLOGY

Summary

This section describes the methodology used to evaluate performance charac­teristics and economic viability of the various PV/thermal solar heating and cooling

... systems examined in this study. The PV systems performance models are discussed briefly which includes the solar array electrical model, a battery model, and the in­verter model. Next, a description is given of the modeling used to evaluate the per­formance of thermal solar heating and cooling systems that apply to this study.

• Then, the economic analysis methodology to be applied to the selected PV/

thermal systems is discussed with the basic assumptions and ground rules identified and the economic model described. In addition, most recent residential electricity and fossil fuel prices are listed for the thirteen locations selected for examination in this study .

Performance Analysis Methodology

PV Systems

Analytical models for the residential photovoltaic power system concepts iden­tified in Section 8 were developed during previous studies to permit the assessment of system performance on an annual basis using hourly insolation and weather data tapes as the input. The analysis methodology in each case is similar in that the programs determine the instantaneous system operating point as a function of individual sub-

~ system characteristics. This operating point of the system is determined for each discrete time increment (one hour) of the total time period (which may be up to one year long) by performing iterative numerical calculations until Kirchoff's Law is satisfied at each node within the system. A detailed discussion of each individual component models and program is provided in Reference 9-1.

Solar Array Electrical Model -- The synthesis of the solar array current­voltage characteristic, as a function of the total insolation on the surface and the

~ solar cell temperature, is modeled based on a single cell characteristic. This cell

9-1

efficiency is 13.3% at an insolation of 1 kW/m2 and at a 2SoC operating temperature. • The total solar array output characteristics are calculated based on the single cell characteristic by multiplying the voltages and currents by the number of cells in series and parallel, respectively. In addition, the series resistance of panel wiring is accounted for in the array characteristic. Figure 9-1 gives the 'calculated I-V characteristic for the shingle solar cell module at two operating temperatures. This module design consists of 19 series-connected, 100 mm diameter solar cells. Tests have shown that encapsulation of this module results in a 7.7% increase in output compared to the bare cell performance yielding a module efficiency of 14.3%. This • increase is due to internal reflected energy from the intercell regions.

The ARCO-Solar Module #16-2000 is used for flat plate ground mounted system analyses. Its characteristics are also shown in Figure 9-1.

"" u..J o:: u..J c.. ~ ,

I-.",

i:l:! 0:: ::> u

I-V CHARACTERISTICS FOR TWO CANDIDATE PV i'lODULES

(MINIMUM AVERAGE PERFORMANCE AT 100' Mlv/cM2)

T I

3,Ot

2,0 t-t

l.°t 0

, I I

CAl BLOCK IV SHINGLE f10DULE

C19 CELLS IN SERIES)

\ I \ I

5 10

VOLTAGE, VOLTS

ARCO-SOLAR f10DULE 16-2000 C35 CELLS IN SERIES)

10 20

VOLTAGE, VOLTS.

28'C

64'C

CELL TEJ"1PEBATU BE

45'C

Figure 9-1. I-V Characteristics for Two Candidate PV Modules 9-2

•

•

•

• Battery Model -- The charge and discharge voltage of a hybrid lead-acid battery has been modeled as a function of battery state of charge (SOC) and instantaneous

charge or discharge ra~e. Qifferent !lets of characteristics are modeled for various

battery SOC conditions. Since the battery is modeled on these actual characteristics,

the round trip efficiency for the battery varies with battery capacity and collector

area for the different cases analyzed. The average round trip efficiency was in the

range of 75 to 88% which incluqes a constant average ampere-hour charging efficiency

• of 0.952. A typical average round trip efficiency is 83%.

•

•

•

Inverter Model -- The type of inverter used in the analysis varied for the

several power conditioning options studied. For the util ity feedback system, a 1 ine­

commutated inverter was used with the. util ity 1 ine providing th~ synchronization sig­

nal. Since different types of inverters were used in different system options and

1 imited performance data WaS avail able for the inverter sizes cons idered in the study,

a constant 87% efficien<;y was assumed for the analyses.

Thermal Systems

To evaluate the performance characteristics of solar heating and cooling energy

systems, a solar thermal· system simulation program developed by General Electric is

ut i 1 i zed. The program s imu 1 ates the thermal system performance by use of mathemat ica 1

models of the system components anqappropriate logic to model the interaction of

these components within the specified system on an hour-by-hour basis. Hourly solar

radiation, meteorological data, building energy requirements and system configuration

data are input to the program. This program and all models are also discussed in more

detail in Reference9~1.

Several space heating, cool ing and domestic water heating system options are

available in the program. The cooling options consist of a solar Rankine-driven heat

pump system and an absorption air conditioner system. The Rankine system uti 1 izes the

GE Weathertron heat pump driven by a sol ar-powered low-temperature Rankine unit. The

system effic iency is ca leu 1 ated from the performance curves of the un it as a funct i on

of vapor generator i Ii let temperature and out(:loor dry bu 1 b temperature. The other

cooling mode alternate uses an absorption air conditioner system based on the ARKLA

SOLAIRE unit models designed:;pecifically for soraI' applications .

The heating mode is modeled as a conventional air-cooled heat exchanger system.

All parasitic power requirements are taken into account in the program and the 9-3 .

appropriate portions of the pumping energy are utilized 'in meeting the building heat­

ing demand. All solar heating and cooling control schemes have auxil'iary back-up

systems with either an electric heat pump or fossi 1 fuel system:

The so 1 ar energy collected c an be stored ei ther ina pressuri zed or non­

pressurized water storage tank as in a liquid collecior ~yste~br arock pile as in an

air collector system. To determirie the amount of energy collected' and stored, itera-

• :

tive calculations are made until thecdllector-heat exchanger-storage loops reach a •

thermal steady-state condition. Energy that exceeds preset values in the collector ,. \,.

array or storage tank will be dumped. Thermal' losses from the loops and storage are

also calculated.

Vacuum Tube Solar Collector' ~- The vacuum tube solar collector developed by

General Electric is a high-temperature performance'collector.' This performance is

achieved by combining vacuum tubes with a nbn-lmagingconcentrator.' The design offers

efficient operation in direct and diffused sunlight and is virtually insensitive to

ambient air temperature or wind conditions. Each collector module consists of 10 . glass vacuum tubes mounted parallel to each other and nestled in 'a simple Vee-trough

reflector.

The thermal performance of the collector is calculated by summing energy gain

and energy loss at the collector absorbing surface.

Given the fluid inlet temperature, ambient conditions and radi ation rate, a

value of the absorber surface ,temperature is determined, in an iterative process,

which results in an overall heat balance.

Combined Solar Thermal Collector -~ The combined photovoltaic/solar thermal

co 11 ector is mode led as a tube and sheet-type collector con\trucHon with"the so 1 ar

cells mounted directly to the absorber plate. The modelihg of this collector perfor­

mance assumes instantaneous response to any thermal changes it encounters and was

described in Reference 9-10.

Economic Analysis Methodology

RLC Ownership and Assumptions

The basic methodology for the economi'c analysis of the Residential' Load Center

(RLC) is a comparison of levelized annual costs with levelized annual benefits of the

9-4

•

•

•

•

•

•

•

•

photovoltaic system. The levelized annual costs include all co~tsassociated with

buying, owning and operating the system, leveliled annu'al benefits derive from the

reduced electricity which must be purchas.ed from conventional sources.

A problem inherent in the RlC concept is the equitable allocation of costs and

benefits among all system users. The five types of RlC under ~tudy al'esingle family

detached houses, town houses, or quadplexes, garden <lpartments.; mobIle homes, and

housing for the elderly. Table 9-1 shows the four mostlik.ely RlC power system owner­

ship categories, appropri ate forms of payment of each and methods to handle excess or

insufficient energy. Not all ownership categories apply to all of the RLC types under

consideration; for example, commercial ownership for single family detached RLC sys­

tems is not anticipated.

In the condominium ownership form, each indivldualowner purchases a share of

the PV system as part of his indivfClual mortgage, thus retaining the benefit of in­

terest tax deductibility. The monthly mainten~nce fee would cover supplemental pur­

chased energy and PV system operation and maintenance CQsts. •. The RLCcooperative

member would have PV system fixed charges (including interest, principal and in­

surance) incorporated into the monthly fee in addition to supplemental energy and

o & M costs. The commerc i a 1 owner wou Idincorporate all PV. system costs into the

monthly rental fee as is currently done in,for example, a master-metered apartment

complex.

Uti 1 ity RLC ownership offers the simplest operation,with the PV system merely

becoming part of the uti 1 ity grid. The owners would 'receiVe a ~entalfee· from the

utility but would otherwise pay for electriCity ilt regular rates. The utility would

maintain the system.

The condominium and co-op ownership forms would require indiVidual meters to

assure equitable cost apportionment. A master meter is also required for supplemental

utility energy purchases and/or sellback. Operation becomeS analogous 10 the rwal

electric cooperative which purchases energy from a large utility and resells to indi­

vidual users. Equitable metering is a major problem with residential load centers .

The recently passed National Energy Act has several provisions which may affect

RLC operation. These include:

9-5

• Table 9-1

RLC Ownership Operating Sceni.rios

, "

I " FORM OF FORM EXCESS SUPPLEMENTAL I

RLC ,j '"

OF ENERGY ENERGY ! "

, • OWNERSHIP P"AYMENT DISPOSITION I SOURCE

!

i ,

I • PV SYSTEM COST I

, ADDED TO OWNER'S MORTGAGES I

I CONDOM I N ruM • "'MONTHL V FEE TO i

COVER PURCHASED,

I " ENERGY, o & M

" "" . " "

1.1 ,

• MONTHLY FEES WITH • SEL~BACK • BUY FROM UTILITY I , REBATES • I

Co-op, •. FEE CQVERS PV, , e; STORE • DRAW FROM STORAGE , "PURCHASED OR GEN-

I • 1 . I P • -ERATED ENERGY, • DISSI ATE AUXILIARY GENER

o & M 'ATION "{ ,

I • INCORPORATE FIXED

COMMERCIAL COSTS & 0 & MINTO REtiT OR FEE (ONL Y

i MAsnp METER I NG) !

, I • NORMAL UTILITY

UTILITY BILLING LESS RENTAL • FEED • FEE GRID GRID

'"

• 9-6

•

•

•

a. Recommendations for new rate structures - time of day or peaking rates - seasonal rates - interruptible rates

b. Restrictions on master metering c. Potential regulations for equitable energy sale to and buy-back of energy

from small power producers.

Time of day, peak load and seasonal rate structures could enhance the value of PV systems in a utility whose peak load is determined by summer cooling requirements. Supplemental energy needed by the RLC would presumably be off peak and thus lower

priced. Interruptible rates could also offer savings, since the most probable inter­ruption period again coincides with the period of greatest PV output.

The commercial form of RLC ownership could be greatly affected if master meter­ing is prohibited. Studies have shown that individually metered apartments consume about 35% less electricity than comparable master metered units, which have little incentive to conserve. Both individual and master units would be required for a com­mercial RLC which would then bill tenants according to use. The typical commercial owner would have little incentive for this mode of operation, particularly if, as a seller of power, he becomes subject to government regulations and reporting require­ments.

The most significant National Energy Act impact could come from regulations which provide for equitable interchange of power between a small power producer such

• as the RLC and the local utility. This could eliminate the need for storage and, particularly when combined with the rate structures mentioned above, greatly improve RLC economics.

• The from of RLC ownership obviously will strongly affect ultimate system eco­

nomics. Table 9-2 presents the economic assumptions to be used in this study and the resultant fixed charge rate (FCR) for the various ownership forms. The condominium and cooperative FCR's are after-tax values, since the owners pay for energy "after taxes", that is, energy is not a tax deductible expense. The condominium has a fur­ther advantage in the tax deductibility of interest on each owner's share of the PV system. This effect varies with tax level; 30 percent is selected as an appropriate

9-7

Tab 1 e 9-2

Economic Assumptions for Different Ownership

1986 START OF OPERATION 1980 DOLLARS 20 YEAR SYSTEM LIFE

10 YEAR BATTERY LIFE

NON-VARIABLE ASSUMPTIONS

INSURANCE GENERAL INFLATION RATE ENERGY PRICE ESCALATION

RATE (ABOVE INFLATION) PROPERTY TAX OPERATION & MAINTENANCE

VARIABLE ASSUMPTIONS

.5% OF CAPITAL COST 5% 4%

o $100/YEAR (SERVICE

CONTRACT)

TYPE OF OWNERSHIP ASSUMPTION

CONDOMINIUM CO-OP COMMERCIAL UTILITY

DISCOUNT RATE 7 % 10 % 10% 9 % EFFECTIVE TAX RATE 30 % 0 25% 48 % FIXED CHARGE RATE 9.4% 11. 75% 14% 16.5%

DEPRECIATION RATE = l/N = .05

9-8

•

•

•

•

•

•

•

•

•

average. The tax deductibility reduces the cost of a ten percent loan to an effective seven percent after taxes. Cooperatives typically return excess payments to the

owners and thus incur no income tax liability. Operation and maintenance are assumed to be covered by a service contract with an estimated cost of $100/year.

Figure 9-2 presents the life cycle cost and benefit relationships for the con-

dominium owner dotted lines. of 100 kwh/m2.

in nomograph form. An example of use of the chart is shown by the

Assume a 1980 electricity price of 4¢/kwh and annual utilized PV output

Levelized annual benefits are 4$/m2 at zero price escalation and, drawing a vertical line upward, are 7.35$/m2 at 4% price escalation. Coming across horizontally to an assumed 50$/m2 balance of plant cost yields a break-even array cost

of 57$/m2. Break-even costs are tabulated below for the above assumptions, and for

each ownership form. The advantage of condominium ownership is evident.

FORM OF BREAK-EVEN OWNERSHIP ARRAY COST

CONDOMINIUM 57.42 $/m2

COOPERATIVE 30.45 $/m2

COMMERCIAL 17.97 $/m2

UTILITY 9.66 $/m2

Table 9-3 presents the advantages and disadvantages of each ownership form, with the forms rank ordered from top to bottom. Condominiums and cooperatives appear

to offer the most promise. Cost allocation can occur within existing frameworks and

fixed charges are low. The main disadvantage is that builders may need incentives to incorporate these systems into their developments, particularly if the systems reduce

the amount of land available for development.

• The commercial sector would have a profit potential if present master metering is permitted; otherwise little incentive exists. The utility application of residen-

9-9

Electricity Price Escalation Rate (Over Inflation)

30 rl--------~~--~r_--~r_----~ 1986 Start

20 I iii I Y --l

Levelized Annual Benefits $/mZ

-Eevelized Costs and Ben2fits $/m

30----,

20

10% Loan 30% Tax Rate 1/2% Insurance No Additional Property Tax 1980 $ 50¢/m2 = l\nnuaJ O&M

'f' (1980 $) ...... o

,150 k \ \ l 7 '"

•

Utilized Annual PV System Out­put

(kW,~!m21, I \ \j \ \ + 10 71-< ~/ ~ I I I V 1 .,;.1. 00 " "" \' 10 I •• r n .. .. ..

o . • I , -=-10 10 20 30 5 0 50 100 150 Annual Savings in 1980 $/m2 1980 Electricity Array Cost = $/m2

Price = ¢/kWh

Figure 9-2. Economic Trade off s f()rCondominium Ownership

• • • • . .

• '. Table 9-3

RLC Ownership Advantages and Disadvantages

• OWNERSHIP ADVANTAGES DISADVANTAGES

• LOWEST FIXED CHARGE RATE • DEPRECIATION NOT USABLE

CONDOMINIUM • TAX CREDITS MAY BE USABLE • POTENTIAL LEGAL BARRIERS

• EASE OF IMPLEMENTATION • BUILDER NEEDS INCENTIVES WHERE FRAMEWORK EXISTS

• LOW FIXED CHARGE RATE • TAX CREDITS AND DEPRECIATION PROBABLY NOT USABLE • CO-OP • EASE OF IMPLEMENTATION • POTENTIAL LEGAL BARRIERS

WHERE FRAMEWORK ~XISTS • BUILDER NEEDS INCENTIVES

• PROFIT IF MASTER METERED • HIGH COST OF CAPITAL

COMMERCIAL • TAX ADVANTAGES • LAND COSTS AND VALUE TO - CREDITS AND DEPRECIATION OWNER

CAN BE USEb. . ,

• SITE FOR ADDITIONAL CAPACITY • RENTAL AGREEMENT WITH HOME-• UTILITY OWNERS

• TAX ADVANTAGES • SYSTEM SIZE MAY BE TOO SMALL

•

tial load centers would have to be driven by a need for sites for additional genera­tion capacity. It is difficult to envision the small relative size of RLC's fulfill­

ing this need.

Energy Price Assumptions Strong regional differences exist in energy pricing, particularly in regard to

electricity and natural gas. A review of recent electric rates in the 13 sites has resulted in the average electricity prices listed in Table 9-4. These values are developed in 1980$ and use typical electric bill publications for 1978 and 1979. Ad­ditional phone contacts with several utilities verified rate assumptions. Table 9-4

also shows fossil fuel price assumptions.

Economic Model Many of the simple investment evaluation techniques, such as payback time or

simple return, suffer from two major drawbacks: 1. Life of the investment is not considered, and 2. Uneven costs and/or benefit streams cannot be handled.

The second item is of critical importance to alternate energy systems since virtually any economic scenario projects risin9 energy prices and therefore a steadily increasing benefit stream from an alternate energy system. For this reason, consi­derable effort has been made to stress "life cycle costing" for energy systems.

Levelized Annual Cost -- True life cycle cost analysis must necessarily con­sider the timing of costs and benefits as well as the magnitude. A method employed in

• :

•

•

previous General Electric solar and wind energy programs is to compare Levelized An- ... nual Benefits (LAB), representing system energy savings, with the Levelized Annual Cost (LAC), the levelized dollar amount required to own, operate, and maintain a sys-tem during each year of the life of the system. Specifically, the levelized annual cost accounts for:

1. "Paying off" system capital costs (mortgage principal) 2. Paying mortgage interest 3. Paying property taxes and insurance 4. Paying operating and maintenance expenses. •

9-12

<D I I-' W

•

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

• ." • • Table 9-4

Summary of Energy Prices

RESIDENTIAL ELECTRICITY PRICES (1980 $)

ENERGY CHARGE REGION (t/kWh)

BOSTON 6.16

WASHINGTON, DC 4.08

CHARLESTDN, S.C. 4.59

MIMlI 4.52

BISMARCK, N.D. 4.56

t/1ADISON, WIS. 5.11

OMAHA 3.28

FT. WORTH 3.-62

NASHVILLE 2.83

PHOENIX 5.20

ALBUQUERQUE 4.87

SEATTLE 1.28

SANTA MARIA, CA 5.63

"

.

RESIDENTIAL FUEL PRICES (1980 $)

NATURAL GAS OIL ($/106 Btu) ($/106 Btu)

5.65 6.77 4.74 6.99

5.36 6.91

7.S9 7.93

3.31 -3.84 6.34

2.74 7.06

3.30 6.27

3.28 5.98

4.75 -3.36 -5.08 6.84

4.49 8.29

-

•

I

i

i

For cost evaluation and comparison of systems for future implementation, it is appropriate to express the levelized annual cost (LAC) referenced to a particular year, e.g., 1975. The result is the levelized annual cost in constant (base year) dollars given by:

LAC (constant $) = CRF' -- x FCR x I + AOC CRF

(9-1)

where I.is the capital cost of the solar system and AOC is the annual system operating cost which includes operation and maintenance and insurance. The parameter FCR is the fixed charge rate and represents the yearly cost of ownership, expressed as a percent of the capital cost, I. These costs consist of mortgage interest, principal and pro­perty taxes. The parameter CRF is the capital recovery factor, defined as the uniform periodic payment (as a fraction of the original principal) that will fully repay a loan (including all interest) in yearly periods over the loan lifetime at a specified yearly interest rate. The interest rate r used to calculate CRF is called the dis­count rate and for the homeowner is equal to the after-tax interest rate of the mort­gage.

The relation expressing CRF as a function of r and system lifetime N is given as

CRF = r(1 + r)N (1 + r)N - 1

(9-2)

The parameter CRF' is the corresponding capital recovery factor in constant (base year) dollars. CRF' is based on the real (or inflation adjusted) discount rate,

• .'

•

•

r', defined as •

1 + r r' = - - 1 (9-3) 1 + g

where g is the general inflation rate. Equation (9-2) applies for CRF' with r' re­placing r.

It should be noted that equation (9-1) applies only to those systems without storage batteries since no replacement costs are necessary. For systems with storage, an add it i ona 1 term of the form

9-14

•

• '.

•

•

CRF' ---=---'--- x I' B (l+r,)l1

(9-4)

must be added to account for the replacement of the battery in the eleventh year (e.g., for a battery life of 10 years). Here, I'B is the cost of the replacement bat­

tery in constant 1980 dollars.

Levelized Annual Benefits -- The comparison of the energy cost savings of the solar system to the levelized annual cost is accomplished by computing the levelized annual benefits (LAB) for the energy savings. LAB is inherently a function of present and projected energy prices and may be expressed by

LAB (constant $) = ~~~' x M x Po x Eo (9-5 )

where Eo represents the annual energy saved by the solar system, M is an energy saving multiplier which is defined as the levelized value of an escalating cost stream which accounts for the rate of energy price escalation over the lifetime of the system, and Po ;s the energy price in year zero (for a 1986 start, year zero becomes 1985). For stand-alone systems, minimum monthly energy charges are included as a benefit in the computation of LAB.

The multiplier M is a function of energy price escalation rate (f), system lifetime (N), and discount rate (r), and is expressed as

M r(l + f)

r - f [ (1 + r)N - (1 + f)N ]

(1 + r)N - 1

* (9-6)

The energy price in year zero (Po) is related to the energy price in constant (base year) dollars per energy unit (p) through the expression

Po = p(~)/), 1 + g (9-7)

where /), is the number of years from the base year to year zero (value of 5 was used • for a 1986 start with a base year of 1980).

* When r = f: M CRF' N

9-15

The economic viability of a system can be measured through the use of the cost­to-benefit ratio, which is defined as the ratio of the levelized annual cost to the levelized annual benefit. The system can be economically viable when the cost-to­benefit ratio is less than unity. The break-even system cost occurs when the ratio is exactly unity, i.e., when LAC and LAB are equal.

References

9-1. Regional Conceptual Design and Analysis Studies for Residential PV Systems, General Electric Company, Report # SAND78-7039, January, 1979.

9-16

•

•

•

• ..

•

• SECTION 10

ECONOMIC AND PERFORMANCE ANALYSIS

Summary

• The rationale for the performance analysis is to evaluate all of the system

•

•

•

configurations for the single family detached conceptual design and then to evaluate selected system configurations for the remaining RLC types. In addition, a baseline

of an all-electric system with utility feedback is analyzed in all of the regions

for the single family detached RLC. Conceptual designs are developed using the PV modules and collector types discussed in Section 9 for each system configuration.

System performance calculations are made for the designs based on hour-bY-hour com­puter simulations and the results combined with life cycle cost analysis based on

system installation cost estimates. The comparison of the cost-to-benefit ratios for the system configurations and locations analyzed for single family detached

houses is presented in Table 10-1. Table 10-2a presents the summary of economic

assumptions used to calculate these cost-to-benefit ratios.

Table 10-2b provides similar summary cost estimates for townhouses, garden apartments, and housing for the elderly. Combining system performance and system

economics for the feedback system configuration is summarized in Figure 10-1 for

these load center types. Residential load centers offer similar economic advantages

as single family detached homes assuming condominium type ownership and homeowner

tax benefits. The major problem is equitable metering schemes for the owners to equally distribute the system benefits.

The mobile home is the last load center type studied. Commercial ownership

is considered and the 14% fixed charge rate for this type of ownership detracts from the overall system economic viability even in high insolation areas.

Additional details on the performance of all the system configurations/site/load center type combinations studied are provided in this section .

10-1

...... o I

'"

1. 2. 3. 4. 5. 6. 7. 8. 9.

10. 11. 12. 13.

Table 10-1

Relative Ranking of Residential System Performance and Economics Through Cost-to-Benefit Ratio for Single Family Detached Houses

PV-Only Systems

Shingle Side-by-Side Systems

I ( a) I(b) I (c) II (a) II (b) I I (c)

Di reet Electric Rank i ne Absorption Charge All Fossil Storage Electric Heat

Reg i on 425 m2 425 m2 425 m2

Boston 1.32 .95 Washington, D.C. 1.32 Charleston 1.09 Miami .98 Bi smarck 1.04 1.2 Mad i son 1.02 Omaha 1.43 Fort Worth 1.23 Nashville 1.90 Phoenix .93 .69 .75 Albuquerque .76 Se att le 5.12 Sant a Mari a .76 1- ___

~able based on 20-yr. life and 4% escalation rate *14% Thermal Collector Area

**Adjustment factor assumes one battery replacement over system lifetime ($100/kWh battery costs)

Solar Electric Fossil Heat Back Up Back Up

425 m2 425 m2* 425 m2*

.98 .93 1.05

.75 .72 .77

.

. . . J

Escal ation Rate System Above Inflation Lifetime**

2% 20 yrs 2% 30 yrs 4% 30 yrs 6% 20 yrs 6% 30 yrs

• • • •

Combined I

Systems

III(a)

Electric I Solar

Heat

260 m2

1.2

1.13

Adjustment Factor

1.47 1.10

.75

.68

.51

-• '.

• Table 1O-2a

Concept Ranking Economic Assumptions "

1986 Start of Operation General Infl ation Rate = 5% Mortg age Rate = 10% T ax Bracket = 35% Additional Property Tax = 0 • Insurance = 0.5% of Capital Cost Operation and Maintenance = $300/yr, Energy Price Escalation Rate = 4% Above Infl ation Sellback-to-Buy Ratio = 0,5 System Life = 20 years Battery Life = 10 years Array Cost = $700/kWg (FOB) ($925/kW~ - $81.1O/m2 @ Site) Battery Cost = $100 kW of Nameplate P ating B a 1 ance -of -PV Pl ant Costs:

System Without Storage* IBOS = $22.66/m2 + $91/kW + $9,120

• System With Storage* IBOS = $22.66/m2 + $91/kW + $12,257

Thermal System-to-PV System Cost Ratio = 2:1 Combined System Cost Same as Thermal-Only System Cost

IBOS numbers are further detailed in Tables 10-6 and 10-7.

•

• 10-3

...... o I

. ~~:.

Table lO-Zb. Summary of System Cost Estimates for RLC Types

TOI~NHOUSE & SINGLE FAMILY DETACHED HOUSING fOR MUL TIPLEX GARDEN APTS. THE ELDERLY

TOTAL COST TOTAL COST UNIT UNIT S 1091 e UNIT TOTAL

COST ELEMENTS COST Multiplex Townhouse COST family Garden Apt. COST COST PV ARRAY $81.10/mt: $22303 $21329 $81.10/mt: $34,468 $32,116 S81.10/m2 $153,036

SOLAR ARRAY $22. 661i $22. 661m2 $22. 66/m2 INSTAllATION $ 6232 $ 5960 $ 9,630 $ 8,973 $ 42,759

(INCl. CREDIT)

POl~ER CONDITION- $2220 + $ 6744 $ 6744 $4316.64+ $11 ,660+ $ 23,938 ING SUBSYSTEM $150.80/kw $90. 88/kw $ 8;861 $ 8,861 $61.39/kw

ELECTRICAL EQUIPMENT $1434 $ 1434 $ 1434 $2161 $ 2,161 $ 2,161 $7251 $ 7,251

ELECTRICAL SYSTHI INSTALLATION LABOR $ 700 $ 700 $ 700 $1152 $ 1 ,152 $ 1 .152 $3148 $ 3,148

METERS $ 298 $1190 $ 1190 $298 " $ 1 ,490 $ 2,384 $198.38 $ 30,550

TOTAL $38603 $37357 $57,762 • $55,647 $260,683

NOTES 1. 1980$ 2. Prices Include (2) 15% Markup Estimates

• • • • '. •

• • • • • 1.2 1.4 ROWHOUSE

I T I BOSTON 0 GARDEN APT. 0

1.21 ~ l.0

...... PS/PE PHOENIX ~

0« T PS/PE

0« IX I IX

------ 0.3 t; 0.8 ~0.3

~ 1.0 ~0.5 ......

'-'- '-'-w ~- --: 0.5 w 0.7 z 0.7 z

0.8 ~ 0.6 w en

0 0

~ 0.4 ~ 0.6

l- I-(I) <- VJ 0 0

0 u 0 L-----+-__ -+~_I- ----+----- -~ u '---+--I------t- - _oj

0 100 200 300 400 500 100 200 300 400

AREA, m 2 AREA, m 2

HOME FOR THE ELDERLY MULTIPLEX 1.0 PHOENIX 1.2 T PHOENIX

0 i ...... I 0 I-' ~ ......

1.0 -l- PS/PE 1 ~ 0 ~ 0.8 0« I I IX U"I I l-I-::;: 0.6

~ ......

0.8 t _.____ _____ 0.3 w '-'-

~_-.0.5 z w w Z co 0.4 w 0.6 . _ 0.7

en 0 l- 0

I-t; 0.2 I- 0.4 0 VJ <-U 0

U 0 lo-rbo 2bo

0 o --+-Tooo--+ 20nO -~ I 300 400

2 AREA, m 2 AREA, m

.Figure 10-1

Summary of Cost to Benefit Ratios for Residential Load Center Types

Single Fami ly Detached

Conceptual Design Reviewing land costs and land availability for mounting PV arrays for RLC's

has led to the emphasis on roof mounted systems. For single fami ly detached homes,

two basic options exist: (1) dispersed arrays on each detached home; or (2) a cen­tralized array on a jointly owned structure. To evaluate these options, a group of

•

six houses were configured with 6.9 kW arrays on each house and compared to a cen- ~

trally located 41.4 kW array. The dispersed arrays are also electrically connected in a series network and a parallel network for comparison, each option having a

central single power confersion unit. Figure 10-2a shows these options along with a baseline case of dispersed arrays and dispersed inverters for each array. The dc

cable length and weight are estimated to limit the power loss to 3% of the total 41.4 kW system rating. The results are listed in Table 10-3.

Alc SERVICE LINES

CA) SERIES, DISPERSED

[] CD rn

le) SERIES; CENTRALIZED ON GARAGE ROOF

Figure 10-2a

Ca) PARALLEL, DISPERSED

(0) DISPERSED ARRAYS AND INVERTERS

PV Array and Circuit Options for SFD Houses

10-6

•

•

•

• '. :

•

Table 10-3 Summary of Cab 1 i ng Requi rements for SFD House Layouts

System Characteristics r

Max i Max

I .

Cable Parameters Power Cable Peak Peak Layout Generated Loss Voltage Current Length Weight Scheme kW kW Volts Amps Ft Lbs

a. Series 41.4 1.24 600 69 434 23 .

b. Parallel Main Seg 41.4 1.24 220 188.2 1345 219

c. Central 41.4 1.24 220 188.2 123 14 d. Individual Reference/Case No External Cabling

-~--..

For the series wired arrays, each array has a rated 100-volt spe.cification

resulting in a 600 V system rating and a 69 Amp system peak current. The drawback

of the series wiring is that the output may be 1 imited if one system becomes inop-

• erative, requiring bypass capability around each house. In addition, differences in house siting may result in different incident insolation levels on each roof creating I-V mismatch characteristics. The parallel wiring option assumes each parallel seg­

ment with a 220 volt rating. This arrangement requires the most copper. Thus, the centrally located array is selected for the analysis.

•

•

A jointly owned garage is selected as the centralized structure. Architectural drawings of the structure are shown in Section 4. Five houses are serviced by each

array on the two garage structures .as shown in the site pl an in Figure 4-2. The PV

array consists of the GE Block IV shingle module with 34 series modules yielding a nominal voltage of 250 Vdc. The parallel circuits are varied from 34 to 64, result­

ing in array area variations of 226 to 425 m2. Module mounting details are discussed

in Reference 10-1. The system peak power outputs vary from 19.8 kW to 37.3 kW. Power conditioning equipment is sized to match the peak array output in the simulations.

Figure lO-2b shows a line diagram of the system conceptual design for an RLC. One

master meter is used to determine energy flow between the RLC and the utility and individual meters per unit to determine each unit's demand. The cost of these meters

would be part of the PV system costs.

Cost Estimates

System cost estimates are made for several design elements and broken into fixed and variable portions. The latter breakdown allows system cost variation with

10-7

..... o I 0.'

•

PHOTOVOLTAI

ARRAY

THREE PHASE UTILITY SOURCE

FILTER SCR BRIDGE

_______ -111 NVERTER CONTROL

ARRAY PRESENCE

UTILITY TRANSFORMER

TRANS­FORMER

UTILITY

-p THREE PHASE 60 HE:RTZ

LOAD DISTRI­BUTION

. ---------,,-------'- .

RES I DENTI AL UNIT #N

SINGLE PHAS!; 3 WIRE 240/120 VAL. UNIT DISTRIBUTION

Figure 10-2 b

Residential load Center Conceptual Arrangement

• • •

B I LLI NG APPO" Tl ON­MENT

RESIDENTIAL UNIT #1

• '.

• array size for the parametric variations. Some of the cost estimates for design elements may be questionable, but an attempt was made to have a representative total system cost and a relative cost comparison between RLC types.

In all cases, the array cost assumed is the National PV Program goal of 70c/peak Watt, or $700/kWp factory price. Assuming two nominal 15% mark-ups for distribution, the on-site cost is $925/kWp, or approximately $81/m2 assuming a conservative average 8.8% module efficiency. The balance of system costs are made up of array installa-

• tion, power conversion subsystem costs, electrical equipment costs, electrical system installation labor, metering, and battery subsystem costs, if required.

The array installation cost estimate is based on labor and material estimates from the 1978 Building Cost File Index for conventional asphalt shingle installation and increased by an assumed factor of three to account for the additional complexity of the PV shingle installation. The resulting cost is $34.75/m2 per unit array in­s tall at i on.

Labor and materi al credit for weather-tight repl acement of the conventional • shingles is assumed at $12.0S/m2 for a net array installation cost of $22.66/m2.

•

•

These values are consistent with residential array installation cost estimates de­veloped by Burt Hill Kosar Rittleman Associates, Reference 11, where non-optimized fl at PV panel install ation costs were approximately $40/m2 and roof credits for in­tegrated arrays were approximately $11/m2. Table 10-4 summarizes these estimates.

Table 10-4 Cost Estimates for Module Installation

Item Unit Cost

• SOLAR ARRAY INSTALLATION Material: Asphalt underlayment, $ 4.76/m2

shingles, nails, wire, etc. Labor: Shingle laydown, asphalt -- underlayment, wiring 29.98/m2

• CREDIT FOR CONVENTIONAL ROOF MATERIAL Material: Shingles, felt, etc. ( 3.72/m2) Labor: -- Shingle laydown ( 8.36/m2)

TOTAL ARRAY INSTALLATION $22.66/m2

The power ·conditioning subsystem cost estimates are based on cost projections

from several inverter manufacturers assuming high production levels in 1986.

These costs are also separated into a fixed and variable cost and then ad­

justed with two 15% mark-ups resulting in the PCS system cost estimate of $4,316 +

$91/kW in 1980 $.

•

Installed metering costs are assumed at $1,490. The remaining fixed balance •

of system cost estimates include costs for junction boxes, disconnect switches, var-

istors, busbars, cabling and miscellaneous connectors, wire and tape and installa-tion labor.· Applying the,mark-,ups resulted in a fixed cost of $2,161 plus $1,152

for labor as indicated in Table 10-5. All of these system cost estimates are sum-

marized in Table 10-6. ~he .unit costs plus the actual total costs of the single

family detached homes RLC are shown. The costs listed in Table 10-6 are basically

direct system costs; however, imbedded in the assumed values are also the indirect

costs associated with syst~m des~gn and installation. Some of the indirect costs

could include ar~hitect fees, real estate fees, interest during construction, pro­

ject management costs and the· cost of thetontingency and spares. Itis difficult

to estimate all of these ihdirect costs and, therefore, they are included in general

terms.

Table 10-5 Electrical Component' Cost Estimates in 1980$

Array Junction Boxes

Disttibution Panels

Miscellaneous Hardware

Wiring

Busbars

Subtotal

Labor

$ 132

198

132

1,173

526

$2,161

$1,152

•

• For the system configuration, including battery storage, additional e lec­

trical equipment,costs of $3,137 are added to the fixed system costs. The breakdown

of these costs is listed in Table 10-7. •

10-10

•

•

•

•

•

Table 10-6 Summary of System Costs for SFD-RLC

r-----.,.-------...,---------.... --------.----.... ----1

Cost Elements PV Array

Solar Array Installation (Including Credit)

Power Conditioni~9 Subsystem Electrical Equipment Electrical System Installation Labor

Meters

Notes: (1) 1980$ (2) Prices include (2) 15% mark-up estimates

Table 10-7

Cost $81.10/m2

$22.66/m2

$4,316 + $91/kW

$ 2,161

$ 1,152

$ 1,490

Battery System Additional Fixed Costs

j----------.---.. --.---~-.-...... ---'."- ....... _ ... _ ...................... ' ..... ,_ .... ',_ ....... _,.-Cost Elements

Control Electronics Shunt Wiring Materials & Labor Battery Encloser & Parts

Battery Installation

Total

10-11

Cost $109

554 1,058

434

$3,137

For the five single family detached homes RLC system, the capital costs are represented by:

PV System with Feedback

I = $103.76/m2 + $91/kW + $9,120

PV System with Storage

= $103.76/m2 + $91/kW + $12~257 + $/kWh

where battery costs were varied parametrically in terms of $/kWh.

Finally, for PV/thermal systems, the costs are varied parametrically in terms of the PV system costs and the proportion of the thermal system size to the PV system size.

ITHERMAL

where (AT/ApV) is the relative thermal and PV collector area and (CT/CpV) is the relative PV and thermal system costs in $/m2. This relationship is used for both side-by-side PV/T systems and the combined PV/T system.

Performance Results PV-Only System with Feedback -- Figure 10-3 summarizes the monthly performance

for maximum power tracking systems with energy feedback to the utility in four cli­mate regions. In all regions, the best load match occurs during the summer months with Phoenix showing the best year-round load match. For the array size of 425 m2, the annual system output is 60% of the total electric loads for the all-electric homes, and over 90% of the annual loads in Phoenix. Since this is the baseline sys­tem for the study, performance calculations are made for all 13 regions. The system output results are correlated in annual total horizontal insolation in Figure 10-4

-for the 425 m2 array area. The total annual system output is represented by Eo in the figure while the energy used directly by the cluster of houses is represented by

Ec and the energy feedback to the utility is indicated by Es. This figure provides

10-12

• :

•

•

•

•

•

I-' 0 ·0 I-' w

• • • .'

15 BOSTON 15 BISMARCK

I I 3: 3: ::E ::E

" 10 ., 10 >- >-t!) t!) a::: a::: I.J.J I.J.J :z :z I.J.J I.J.J

>- >-5 -J 5 -J

I I l- I-:z :z a a ::E ::E

PV SYSTEM OUTPUT (52.6 MWh) I PV SYSTEM OUTPUT (63.4 MWh)

I 3: ::E

" >-t!) a::: I.J.J :z I.J.J

>--J I l-:z a ::E

01 I I I I I I I I I I I I 0

J

PHOENIX ~ lOT

NASHVILLE 10 rLOAD (71.8 MWh)

::E

" >-t!) a::: I.J.J 5 :z 10

>-PV SYSTEM OUTPUT (83. 9 r~Wh)

-J 1 '''"- PV SYSTEM OUTPUT I I- (57.6 MWh) :z a

0 ::E

J

Figure 10-3

Monthly Performance of PV Only System Without Storage for Single Family Detached (425 m2)

•

220

200

180

N 160 E

----..<::: 3: 140 -"'! . >-(!) 120 n:: w z w 100 -' .<:( :::> z 80 z

1-' <:( 0 I I-' 60 .po

40

20

0

•

I BOSTON 2 WASH. D.C. 3 CHARLESTON .. MIAMI :; BISMARCK , MADISON 7 OMAHA • FT. WORTH t NASHVILLE

10 PHOENIX 11 ALBLaUEROUE 12 5EATILE 13 5ANT A MARIA

1)'/

7Y< ~)!3 . 9

'2 13

E

11 // 0

,/(10

11 ./ ts //~

tD

ARRAY AREA

425 m2

bY "-"'i---._._ .. __ .-t •. _.-... - ..... I· .. ······· .... - .•... -j-.. ...._--f--

500

•

1000 1500 2000 2500 3000

ANNUAL TOTAL HORIZONTAL INSOLATION. kWh/m2

Figure 10-4

Annual Energy Output Correlation for PV-Only System with Utility Feedback for the Single Family Detached RLC

• • •

• an estimate of each of the system output energy values for any location based on its

annual total horizontal insolation level.

The performance of the feedback system is also calculated for various col­

lector areas in four of the regions. The shingle array was varied from 34 parallel circuits to 64 parallel circuits (226 m2 to 454 m2). Table 10-8 lists summarized performance data for all of the locations and area vari ations for the feedback sys-

• tem.

U is defined as a utilization term which adjusts the value of the energy fed

back to the utility by the sellback-to-buy price ratio, PS/PE.

U = Utilization = 1 - (1 - ~)~ PE EO

In addition, the term ED, which is the annual PV system "direct" energy in

kWh, is equal to the difference of the PV system output, EO, load, LE, and the utili-

• ty "make-up" energy, EUM, for PV-only systems without storage. The values for the "utilization" listed in Table 10-8 use a sellback-to-buy ratio of 0.5.

•

•

Using system cost estimates, levelized annual costs and benefits are calcu­lated and cost-to-benefit ratios are used for comparisons on the system configura­

tions. Figure 10-5 summarizes the economic results for the all-electric system for a group of five detached homes. The array size optimizes at the maximum available roof

area on the garage in all the regions for a buy-back rate of 50% or greater for feed­back energy to the utility. As the buy-back rate decreases, the optimum system size is reduced. Figure 10-6 provides a comparison of the system for the different re­

gions for several array costs assuming a 50% buy-back rate. The system again opti­mizes at an array area of 425 m2 for the baseline array costs of $80/m2. These

curves actually represent variations in total variable system costs whether they are a result of different array costs, array installation costs, or other system variable costs. As the system costs increase from $80/m2 to $200/m2, the slope in the cost­

to-benefit curves changes and smaller sized systems are indicated.

PV-Only System with Fossil Heating -- A common system configuration is a fos­

sil heating/fossil domestic hot water system for the cluster of single family resi­

dences is made. The results of the annual simulations for the two systems are shown

10-15

• Tab le 10-8

PV-Only Systems Performance System for All-Electric Loads with Feedback

i NET ELECTRICAL ARRAY SYSTEM UTILITY FEEDBACK LOAD AREA MAKE-UP ENERGY ApV

OUTPUT EUM ES LE

UTILIZATION EO U

REGION - (m2) (kWh) (kWh) ( k~~h) ( kl4h) PS/PE = 0.5 • PHOENIX 34S' x 64P 425 83,857. 42,208 46,381 79,685 .723 34S x 50P 332 65,590 44,232 30,137 79,685 .770 34S x 34P 226 44,350 48,186 12,852 79,685 .855

NASHVILLE 425 57,608 47,939 33,761 71 ,786 .707 332 44,892 49,533 22,638 71,786 .:'48 226 30,166 52,251 10,631 71 ,786 .824

BOSTON 425 52,556 59,543 29,955 82,144 .715 332 40,912 61,142 19,908 82,144 .757 226 27,447 63,871 9,174 82,144 .833

, • BISMARCK 425 63,678 75,632 35,486 103,824 .721 332 49,634 77 ,974 23,782 103,824 .760 226 33,375 81 ,923 11 ,472 103,824 .828

ALBUQUERQUE 425 87,855 43,671 57,697 73,829 .672

CHARLESTON 425 61,440 41,944 35,405 67,979 .712

FORT 140RTH 425 68,232 44,429 38,264 74,397 .720

MIAMI 425 64,854 41 ,378 31 ,054 75,178 .761

SANTA MARIA 425 76,434 33,610 51 ,006 59,037 .666

MADISON 425 58,207 65,717 32,794 91 ,130 .718 • OMAHA 425 64,716 59,236 36,129 87,823 .690

SEATTLE 425 46,658 52,973 26,593 73,038 .715

l-JASHINGTON, D. C. i 425 56,097 57,832 31 ,042 76,887 .723 ,

• 10-16

• 0 1.4 ....... I-.:t a: I- 1.2 ....... lL..

- w z 1.0 w co 0 0.8 I-

l-V> 0 0.6 u • 0

0 ..... 1.2 l-

~ I- 1.0 ...... lL.. w z 0.8 • w co

0 I- 0.6 I-V> 0 u 0.4

0

•

•

BOSTON 1.4 BIS/MRCK 0 .....

PS/PE --+ I-

PS/PE I eX; 1.2 a: 0.3 I

0.3 ----r l-..... 0.5~ lL.. 1.0

O.~ 0.5 - I w 0.7 z:

~ w co 0.8 0 I-

I- 0.6 V> 0 u

0 0 100 200 300 400 500 0 100 200 300 400

AREA, m 2 AREA, m2

PHOENIX 0 NASHVILLE

....... 2.4 I-

.:t PS/PE ~ ce:

I- 2.2 0.3 I ......

lL..

PS/PE ---+ w I z: 2.0 w 0.5~ 0.3 co "-

0.5 0

0.7~ -- I- 1.8 0.7 l-V>

+ 0 1.6 u

I L

Ido 260 3bo I I 0 400 500 100 200 300 400

AREA, m 2 AREA, m 2

Figure 10-5

Economic Tradeoffs for the All-Electric PV-Only System for the Single Family Detached RLC

10-17

500

500

0 BOSTON 0

BISMARCK ...... 2.5 ...... 2.5 ARRAY I- ARRAY I-

"" "" COS! cr: COST cr: I- 2.0 $/m2 I- 2.0 $/m + o 1986 START ..... ......

200 lL. r lL.

o 10% MORTGAGE w 200 w ~~ 1.5 z: 1.5 I 4% ESCALATION ABOVE w w

125- 0 en ca 5% INFLATION 0 125 0 1.0 80- I o 20 YEAR LI FE I- 1.0 80 l-

I- I- o 30% TAX BRACKET V) V)

O~ 0 0.5 o _ 0 0.5 u u

0 0 100 200 300 400 500 o 0 100 200 300 400 500

AREA, m 2 AREA, m 2

PHOENIX 5 NASHVILLE

0 2.5 ...... ...... 0 0 I- .....

ARRAY I "" 2.0 I- 4 ...... cr: ARRAY "" COST (X) c::

l-I-COS! $/m2

200 ..... l-lL. 1.5 .....

3 w $/m -----+ I..L. z: w 125 w

200 z: ca w 2 1.0 125 I

ro 80 0 I- 80 0

l-I- 0.5 l- I + 0-V)

0 0 V) u 0 u 0 0

0 100 200 300 400 500 0 100 200 300 400 500

AREA, m2 AREA, m2

Figure 10-6

• Parametric Tradeoffs for System Variable Costs for the"'l-Electric PV-Only System4llr the Single Family DetactIJ RLC • '.

•

•

•

•

•

in Table 10-9. The use of fossil fuel to supply space heating and DHW load reduces the total electrical load and, thus, just simply changes the load profile for the load center. The most dramatic changes in the load occur for regions of high heating

demands as Bismarck with smaller reductions in areas as Phoenix and Forth Worth. Since the system output is the same, the result is a different distribution of the energy used directly in the residence and the amount sold back to the utility. The last two columns of Table 10-9 show the changes in distribution of the energy used

directly in the residence. In general, the sellback energy increases for the fossil heating system and, thus, depending on the utility buy-back rate, these systems are

not as cost-effective as the all-electric system on a cost-to-benefit ratio basis.

Figure 10-7 shows the comparison of the annual system output for the two sys­

tem configurations and shows the energy distribution trends.

Since the same system size is used as in the all-electric system case, system

costs are the same; however, levelized annual benefits are different due to the ener­gy distribution. This comparison is shown in Figure 10-8 between the two system

configurations. Studying the trends of economic performance with array area and

array variable costs, system sizing still tends toward the maximum available roof area, Figure 10-9.

PV-Only System with Battery Storage -- Previous studies have indicated that energy feedback to the utility at rates of 50% or higher of the buy price are more cost effective than battery systems. Therefore, the all-electric system with battery

storage is only analyzed to two regions: Boston and Phoenix. The batteries are assumed centrally located in the garage area. Figure 10-10 shows the general perfor­mance trends of annual system output with battery capacity and array area. The

monthly PV system output and load requirements for a 425 m2 array and a 150 kWh bat­

tery capacity at these locations are plotted in Figure 10-11. The excess output of the system is also shown which occurs during the seasons of lowest load demand. This

energy must be shunted to ground or possibly used for direct water heating. However,

this use is not practical for the group of single family detached homes with hot

water heaters in each home. Table 10-10 summarizes the performance parameters for these systems .

10-19

I-' o I

N o

•

SYSTEM

FOSSIL HEATING

AND FOSSIL

DHW

ALL ELEC-TRIC

C::ITY

PHOENIX

BISMARCK

Ft. WORTH

PHOENIX

BISMARCK

Ft. WORTH

•

Table 10-9. System Performance Comparisons for Sinqle Family Detached Homes

% OF PV NET FEED- ELECT- DIRECT

ARRAY SYSTEM UTILITY BACK RICAL ENERGY AREA OUTPUT MAKEUP ENERGY LOAD TO

Apv Eo Eurn Es Le LOAD 2 kWh kWh kWh kWh EO/E rn

425 83857 30416 53148 61125 50.2 332 65590 31757 36223 II 48.0 226 44350 34483 17708 II 43.6

425 63678 21068 46540 38206 44.9 332 49636 21856 33283 " 42.8 226 33375 23380 18548 " 38.8

425 68232 28573 43820 52985 46.1 332 53260 29797 30072 II 43.8 226 35899 . 32255 15169 " 39.1

425 83857 42208 46381 79685 47.0 332 65590 44232 30137 " 44.5 226 44350 48186 12852 II 39.5

425 63678 75632 35486 103824 27.2 332 49634 77974 23782 II 24.9 226 33375 81923 11472 II 21.1

425 68232 44429 38264 74397 40.3

------------ - - - ---

• •

% OF DIRECT ENERGY

TO OUTPUT EDlo

36.6 44.8 60.1

26.9 32.9 44.4

35.8 43.5 57.7

44.7 54.1 71.0

44.3 52.1 65.6

43.9 ,

--- --

•

• 220t 200

180 +

N' 160 E

........

.c: 3: 140 ~

~

>-(!) 120 c:: w z: w 100 -J c:( => z: 80 z: c:(

60 t ~-.,

0 I

N ,.." 40

20

0

• • • • / EO

1 IJQ5TQN 2 WASH. b.t. 3 CHARLESTON

• MIAMI ARRAY AREA 5 BISMARCK

425 m2 6 MADISON 7 OMAHA E • FT. WORTH /' S • NASHVILLE /'

10 PHOENIX /'

II ALBl.OUEROUE /" r-S 12 SEATTLE /'

13 SANTA MARIA /'

/'

/' /"./ ED ALL ELlCIR I C

- - - FOSSIL HEATING + DHW /" ~

/'

/' ~ ~ ---E ...- D

~.--- ELECTRICAL LOAD COMPAR1SQ;"J --..--PHOENIX BISMARCK FT. WORTH

--- ALL ELECTRIC (kWh) 79685 10332~~ 74397 --FOSSIL HEATING (kWh) 61125 38206 52985

500 1000 1500 2000 2500 3000

ANNUAL TOTAL HORIZONTAL INSOLATION, kWh/m2

Figure 10-7

Correlation of System Output for PV-Only Systems with Feedback

Single Family Detached RLC

a +' ro c:r:: -I-'

4-QJ <:: QJ

o::l , a

-I-' , -I-' Vl I-' a 0 w ,

N N

•

1.4f

1.3 r 1.21

1.1 !­i

1.0 ~ 0. 9 r

,

0.8 r

All-Electric

Bismarck ~

:::L, Phoe"" m~ 100 200 300 400.

Array Area, m2

a .~

+' ro c:r:: -I-'

4-QJ <:: QJ

o::l , a +' , -I-' VI a w

1.4 Fossil Heating/Hot Water

1.3

1.2 Bismarck

~

0.8 Phoenix __ -------0.7

0.6 100 200 300 400

Array Area, m2

Figure 10-8. Comparison of All-Electric Systems and Fossil Heating Systems

• • • •

• • • • • 3 r Bismarck 1.5r Phoenix a o .

.~

. Array Cost = 80/m2 .~

Array Cost = 80/m2 +' +'

'" m 0:: 0::

+' i ! l.°r PS/PE 4- 2 <-

PS/PE <lJ I

- .3 c I <lJ .3 c:l I .5 I I a .7 +' .5 I

1 ~ I

+' .7 +' 0.5 VI VI 0 0

u u

I o Lv I I I I O~ 100

I I ioo 200 300 400 200 300 400 Array Area, m2 Array Area, m2

3 r

PS/PE .5 I-' 0

Array Cost ($/m2) 0

0 .~ .~

I +' +'

2l

PS/P E = .5 N '" '" W 0:: 0::

+' 200 +' Array Cost ($/m2) .~ 2 4- 4-<lJ <lJ c 125 c <lJ <lJ

c:l c:l I 80 I

1 f 200 a 0

+' +' 125 I 1 I +' +' VI

0 VI 80 0 0

u u

0

0 l/ I

100 200 300 400 '100 200 300 400 Array Area, m2 Array Area, m2

Figure 10-9. Economic Tradeoffs for PV-Only System With Fossil Heating/Hot Water

.c :s: ::;;:

~

+-' ::::; 0-+-' ::::;

0

E Q)

+-' til >, Vl

~

<e t-' ::::; 0 c 1 C N <:( -I=>

•

PHOENIX Array Area m2 70 r BOSTON

70 r

~425 ~ 60 f 60 t Array 332 Area ---50

m2 .e- 50 I ::::;

40 ~ 0 425

?-332 ~ 40 r 226 ---! 30 t

30

226 20

§ 20 <:(

10 10

o I I 1 I I 1 0 50 100 150 200 250 01 -L-___ -L..-----t

Battery Capacity, kWh 0 50 100 150 200 250

•

Battery Capacity, kWh

Figure 10-10. Performance Summary for SFD All-Electric Systems With Storage

• • •

I-' o I

N U""l

•

.<: ::s:: ::E

>, en >­Q) C

W

>, ~

.<: ..., c o

::E

• • BOSTON

8

6

4

2

o

.<: ::s:: ::E

>, en >­Q) c w >, ~

.<: +' c o

::E

12

10

8

6

4

2

o

•

/ I

/ ,

PHOENIX

r-----. \ I \~J ~,

"'--system Output

Excess

J F M A M J J A ~ 0 N D J F M A M J J A SON D

Figure 10-11. Monthly Performance for Single Family Detached PV System With Storage

•

I-' o I

N Q)

!

REGION

BOSTON

II

PHOENIX

I

I 1 , , Y

•

) I

I J I

I I

i

,

Table 10-10. Sunmary Perfonnance of PV System with Battery Storage for the SFD-RLC

NET 1

ARRAY BATTERY SYSTEM UTILITY BATTERY I BATTERY ANNUAL AREA CAPACITY OUTPUT ~AKE-UP CHARGE 1 DISCHARGE EXCESS (m2) (kWh) (kl~h ) kWh) (kWh) (kWh) (kWh)

425 48 29,404 52,739 19,207 14,045 14,039 332 I 27,072 55,072 17,081 13,244 6,391 226 J, 21,367 60,777 13,108 10,949 960

425 144 38,933 43,211 28,508 24,248 3,149 332 , 32,637 49,507 21,882 19,322 400 226 J 22,464 5"9,680 13,328 11,904 1.4

425 240 40,560 41,584 29,245 25,651 1,535 332 1 33,012 49,131 21 ,690 19,504 107 226 22,547 59,597 12,993 11 ,73O 1.5

425 96 59,131 20,553 37,892 30,438 6,582 332

J 53,369 26,316 30,565 26,304 1,480

226 38,597 41,088 19,710 17,433 3.33

425 144 65,477 14,208 42,648 36,156 3,377 332

~ 55,338 24,349 31 ,849 28,000 632

226 38,685 40,999 19,725 17,582 -0-

425 240 67,264 12,419 43,395 37,476 2,261 332 t 55,863 23,822 32,080 28,554 385 226 38,878 40,803 19,037 17,108 -0-

- ---

• • •

I

LOAD (kWh)

82,144

J 82~144

1 82,144

t 82,144

J 79 1685

J 79,685 I

I 1 i

•

•

•

The net annual output for the battery system is also correlated with annual total horizontal insolation and compared to the feedback system in Figure 10-12. As shown, the net system output for the same array is greater for the feedback system.

The PV system costs, as described in the previous section, are used for the economic analyses of these systems. Fi gure 10-13 and Fi gure 10-14 present parametr i c comparisons of the cost-to-benefit ratios for various battery costs, battery capaci­ties and array costs and sizes in Phoenix and Boston, respectively.

One hundred fifty kWh appears to be the nominal battery capacity for the 425 m2 array area. For the Phoenix area, with the given set of economic assumptions, this system shows economic viability with battery costs of $100/kWh or less.

Side-by-Side PV/Thermal Systems -- Side-by-side PV/thermal system analyses for the single family detached RLC type also use the centralized garage roof for the collector arrays. Three systems are evaluated using an evacuated tube solar col-

• lector along side the PV shingle array: (1) a parallel solar heat pump system; (2) a solar driven Rankine heat pump system; and (3) a solar heating and absorption cooling system. Block diagrams of the system were shown in Section g. All of the PV systems rely on utility feedback. The percent of the roof area covered by thermal collectors is varied. The systems are evaluated at two extreme climate regions, Boston and Phoenix. Figure 10-15 shows the PV and thermal annual energy performance summary for the systems in the two regions. The PV output is proportional to the PV area since the sellback mode allows full utilization of the collected energy. The thermal out­put, which is defined as the useful solar energy contributed to the residence needs,

• on the other hand, is a strong function of energy demand on the system. The curves show a diminished rate of solar utilization with larger collector area resulting principally from the mismatch of generation and demand and the consequent need to discard large amounts of energy. This trend is especially true for the parallel heat pump system in Phoenix. The annual energy output for space heating, cooling and domestic hot water for the remaining two systems are higher as the otherwise dis­carded energy collected during summer months is utilized for cooling.

Economic tradeoffs for these systems considered varying total thermal system

• costs in $/m2 per unit of collector area (CT) relative to the PV system costs (CPV)

10-27

N E --....

.>::: :3: ~

>-(.!) c.:: UJ z UJ

-I o::c => z z

~ o::c 0 • N

00

•

220

200 I Z 3

180 4 5 ,

160 1

• , 140 10

II t2

120 13

100

80

60

40

20

0

D05TON WASH. D.C. CHARLESTON MIAMI BISMARCK MADISON OMAHA FT. WORTH NASHVILLE PHOENIX ALBLOUEROUE SEATTLE SANTA MARIA

//

/

//

500 1000

/

/

/

1500

SINGLE FAMILY DETACHED

/

2000

/

Eo

EO/' /'

ARRAY AREA

425 m2

---- WITHOUT STORAGE

WITH STORAGE

2500 3000

ANNUAL TOTAL HORIZONTAL INSOLATION, kWh/m2

Figure 10-12

Annual Energy Output Correlation for the Battery System for the Single Family Detached RLC

• • • •

• 0 .~

+' n:l 2 ex: +'

4-GJ C GJ

CCI I 1

0 +'

I +' Vl 0

u

00

..... 0 I

N <D 0

.~

+' n:l 2 ex: +'

4-<lJ c <lJ

CCI I 1 0

+' I

+' Vl 0

u

o 0

• • • • Array Area = 226 m2 0 Array Area = 332 m2

0 f Arr,y Are' ~ 425 .2 Array Cost $80/m2 ::; Array Cost = $80/m2 .~ Array Cost = $80/m2 +' Battery Cost~ 2 Battery Cost n:l 2 Battery Cost ex:

$/kWh +' $/kWh +' $/kWh 100 .~

~O 4- 4-(l) GJ c 100 c <lJ <lJ

1 r I 100 'f 1 ~O CCI

~ I ~ 0 0 I +' 0 +' 0 I I --I

+' +' Vl Vl 0 0 u u

o 0 0 50 100 150 200 250 50 100 150 200 250 0 50 100 150 200 250 Battery Size, kWh Battery Size, kWh Battery Size, kWh

Array Area = 33£ m2 Array Area = 332 m2 ~ Arr,y Are' - 425 .2 Battery Cost = $50/kWh 0 Battery Cost = $50/k Wh 0 Battery Cost = $50/kWh .~ .~

+' +' Arr2Y Cost n:l

2 Arr~y Cost n:l 2 . Arr~y Cost ex: ex: $/m +' $/m +' $/m

.~

200------4- 4-Q) Q)

1 ~ 200~ c 200 - C

12~· <lJ <lJ

CCI co 125~ I 1 125 --- I

8 . 0 0 80 I +' 80---- +' -------O~ I I

+' +' Vl 0--- Ul t- O 0 0 u u

50 o 0 50 100 150 200 250 o 0 50 100 150 200 250 Battery Size, kWh Battery Size, k'iJh Battery Size, kWh

Figure 10-13: Economic Tradeoffs for All-electric System With Battery Storage for the Single Family Detached RLC in Phoenix

... -.

Array Area 226 m2 Array Area 332 m2 r Array Area 425 m2 0 Array Cost $80/m2 0 Array Cost = $SO/m2 0 Array Cost $SO/m2 .~

.~ .~ ...., 2 -:;; 2 ....,

2 to to a::: a::: a::: I 100 I ...., ....,

~ ....,

.~

~100 '+- '+- '+-a..> a..> a..> \:: c ~ \:: ~ ==5~ a..> a..> a..> co

1 "i' 1 ~ co 1 I 0 I 0 0 0 ...., ...., ....,

I I Battery I I Battery ...., ...., ...., l/) Cost l/) l/) Cost 0 0 0 u $/kWh u u $/kWh

Q ---'-- 0 0 0 50 100 150 200 250 0 50 100 150 200 250 0 50 100 150 200 250

Battery Size, kWh Battery Size, kWh Battery Size, kWh

I-' Array Area = 226 m2 Array Area = 332 m2 Array Area = 425 m2 0 0 Battery Cost = $50/kWh 0 Battery Cost = $50/kWh 0 Ba~tery Cost = $50/kWh I

.~ .~ .~ w ...., 20~ -:;; 2 200 ...., 200 0 to 2 ~

reS 2 a:: a::: a::: ....,

1~ ...., ...., 125 I 12~ .~

80~ '+- '+- '+-a..> a..> a..> c SO \:: S~ C

~ a..> a..> a..> co

~ co co

I 1 I 1 I 1 0 0 I 0 I ...., ...., 0 Array~

...., I I I

~ ...., ...., ...., l/) Array Cost l/) l/) 0

$/m2 0 $/m2 I

0 $/m2 I u u u

0 0 o 0 50 100 o 0 50 100 150 200 250 Battery Size, kWh Battery Size, kWh Battery Size, kWh

Figure 10-14. Economic Tradeoffs for the All-Electric System With Battery Storage for the SFD RLC in Boston

• • • • •

.<:: 3: :<:

+' ~ D-+' ~

0

E ill +' til »

(/")

..... 0 , '" w ::0 ..... s::

s:: <:(

• • • • • r-i30STON PHOENIX . -I

JOO

90

80

70

40 ~ 301

o 10 20

100 80

100

.<:: 3: :<:

+' ~ D-+'

Rankine + ~ 0

Absorption E

Systems ill +'

'" xpmllelHP » (/")

~

'" ::0 s:: c

~" PV System <:(

'~ ~

~~~--~ 30 40 50 60 70

i

80 90 100 Therma 1

! I

60 40 10 0

Percent Collector Area PV

90

80

70

60

50

40

30

20

10

'~

Absorption System

Rankine System

"~~ HP

7 ------Parallel ~V system

':-----,'-~-::-':---:'::--4~0· 50 60 70 80 90 1'00 o 10 20 30 , , , I , T~erma 1

100 80 60 40 20 0 PV

Percent Collector Area

Figure 10-15. Performance Summary of Side-by-Side PV/Thermal Systems for Single Family Detached Homes

based on PV system costs goals. The capital cost assumptions are discussed in the previous section. Figures 10-16 and 10-17 show these economic tradeoffs for each of

the three systems in Boston and Phoenix. An oil fossil fuel price of $6.77/MM BTU is assumed for the fossil heating system in Boston, and a gas price of $4.75/MM BTU in Phoenix.

At system cost ratios greater than 1 (CT/CpV >1), minimum sized thermal sys­tems are implied. It is noted, however, that in Boston, the cost-to-benefit ratio

for the parallel heat pump system tends to have minimum at reasonable thermal array areas for thermal system costs equal to PV system costs. In Phoenix, on the other

hand, the trend of decreasing cost-to-benefit ratios exists for all CT/CpV ratios, which still implies minimum, or no, thermal area. In comparing the two systems, the

Rankine driven heat pump system shows similar trends as the parallel heat pump system in each location; whereas, the absorption cooling and direct heating system, at cost

ratios of 1 or less, would tend toward larger thermal array areas in both locations.

The sellback rate also affects the thermal system sizing. As the sellback rate increases, smaller thermal arrays are again indicated. Figures 10-18 and 10-19

show these effects for the solar Rankine heat pump and the absorption/fossil heating systems, respectively.

Tables 10-11a through 10-11c summarize the annual performance data for the side-by-side systems.

PV/Thermal Solar Hot Water Heating System -- Since solar hot water heating systems are currently available and reasonably economic, the analyses are extended to

side-by-side PV/thermal systems where the thermal system only provides domestic hot water requirements.

Several solar thermal collector areas are evaluated for the feedback PV system

to determine the percentage of hot water load that can be supplied by such collector systems. All collectors are again located on the garage roofs. The solar thermal panels reduce the total electrical energy requirements of the system.

Table 10-12 summarizes the system performance for the domestic hot water runs completed for the single family residence (SFR) in three regions.

10-32

•

•

•

•

• • • • • Sellback To Buy Ratio = .5

Parallel Rankine Driven ~sorption A/C Heat Pump Heat Pump Fossil Heating

CT/CpV Oil Fossil 1.6 I 1.6 [ CT/CpV ].6 r Fuel

2.0 $6. 77/MMBTU 1.4 1.4 1.4 CT/Cpv

a a a .~

.~ .~

+-' +-' 2.0~ +-'

<0 1.2 <0 1.2 <0

1.2 r 0:: c:r: c:r: 2.0 +-' +-' +-' ~ 4- 1.0 1.0 4- 1.0 4- 1.0 Q)

Q) OJ

C C C

Q) Q) 1.0 '----

Q)

~ co co co

I 0.8 O. 5 --------

I 0.8 , 0.8 t 1.0

a a ~

a t-' +-' +-' +' 0 I I 0.5 I

I +-' 0.6 +-' 0.6 +-' 0.6 0.5

w Vl Vl Vl

w a a a u u u

0.4 0.4 0.4

0.2 0.2 0.2

0 a 0 0 100 200 300 400 500 0

o ... 100 200 300 400 500

PV Area, m2 PV Area, m2 PV Area, m2

I I i·

300 200 100 0 300 200 100 0 300 200 100 0 Thermal Area, m2 Thermal Area, m2 Thermal Area, m2

Figure 10-16. Comparison of Economic Tradeoffs for SFD RLC Side-by-Side Systems in Boston

Sellback to Buy Ratio •. 5

Parallel Rankine Driven Absorption A/C Heat Pump Heat Pump Fossil Heating

1.6 r CT/CpV 1.6 2.0 CT/Cpv

1.4f

Gas Foss il Fuel 1.4 $4. 75/MMBTU

0 0 0 .~ .~ 2.0 .~

+-' 1.2 +-' +-' 1.2 r CT/CpV ro ro ro a: a: a:

+-' +-' +-'

4- 1.0 1.0~ 4- 4- 1.0

Q) Q) Q)

2.0~ c c C ill ill 1.0 ill ro 0.8 ro co 0.8 ,

0.5~ , ,

0 0 0 +-' +-' +-'

1.0 :==? ...... ' , 0.5 ____ , o+-' 0.6 +-' +-' 0.6 , VI VI VI W 0 0 0 0.5 .,.w u w

0.4 0.4 0.4

0.2 0.2 0.2

0 0 0 0 100 200 300 .400 500 0 100 200 300 400 '500 0 100 200 300 400 500

PV Area, m2 PV Area, m2 PV Area, m2 I I I I I J I

300 200 100 0 300 200 100 0 300 200 100 0 Thermal Area, m2 Thermal Area, m2 Thermal Area, m2

Figure 10-17. Comparison of Economic Tradeoffs for SFD RLC Side-bY-Side Systems in Phoenix

• • • • •

•

•

•

•

•

1.4

.~ 1.2 +' to

0:: 1.0

;;:: 0.8 Q.J <::

~ 0.6 I

a "i' 0.4 +' V1

8 0.2

CT/CPV

2.b~

1.0_

0.5/

PS/PE = 0.3

a !!!!

o 100 200 300 400 500

.~ 1.2 +' to

0:: 1. 0

4-Q.J <:: Q.J co

I a +'

I +' Vl a u

PV Area, m2 I I I I

300 200 100 0 Thermal Area, m2

PS/PE = 0.3

PV Area,m2 I I I I

300 200 100 0 Thermal Area, m2

1.4

.~ 1.2 +' to

0:: 1.0

4- 0.8 Q.J <::.

~ 0.6 I a "i' 0.4 +' Vl

8 0.2

o

.~ 1.2 +' to

cr: 1.0 +'

4- 0.8 Q.J <:: Q.J

co I

o +'

I +'

0.6

~ 0.2 u

Boston

CT/CpV

2.0~

1.0,----

0.5~

PS/PE = 0.5

PV Area, m2

I I 1 I 300 200 1uO 0 Thermal Area, m2

Phoenix

CT/CpV

2.0 \

1.0~~ o . 5 -----::::

PS/PE = 0.5

1.4

.~ 1.2 +' to

0:: 1.0 +'

4- 0.8 Q.J <:: Q.J co

I o +'

I +' Vl a u

0.6

0.4

0.2

CT/CpV

2.0

1.0 \ ~

0.5 -----

PS/PE = 0.7

OL,;,-;:-:!-::--:::-':-:::-:::'=-!-::~ o 100 200 300 400 500

PV Area, m2

I I I I 300 200 100 0 Thermal Area, m2

a 1.2 CT/CPV

~ 2'0~ ~ 1.0

4- 0.8 1.0

~ 0.6 0.5~ a +'

I +' Vl o u

0.4 = 0.7

0.2

o 100 200 300 400 500

PV A)'ea, m2 o 100 200 300 400 500

PV Area, m2 I I I I

300 200 100 0 Thermal Area, m2

I I I I 300 200 100 0 Thermal Area, m2

Figure 10-18. Economic Tradeoffs for SFD RLC Side-by-Side Rankine System

10-35

0 .~

+' to

cr: +'

4-aJ <: aJ cc

I 0 +'

I +' Vl 0 u

0 .~

+' to cr: +'

4-QJ <: QJ

cc I

0 +'

I +' V1 0 u

Boston

1.4- CT/Cpv 0 1.4 CT/CpV 0

1.4 CT/CpV .~ .~

1.2 +' +' 1.2 2.0~ to 1.2 2.0 to

cr: "'---- cr: 2.0~

::~-J +' +'

1.0 1.0 1.0 4-

-;/ 4-

aJ aJ <: 1.0 <:

0.8 1.0/ 0.8 aJ 0.8 QJ

cc cc I I

0.6 - 0 0.6 0.5 0 0.6 +' +' 0.5 I I

PS!Pr-:: 0.3 +' PS/PE = 0.5 +' 0.4 Vl 0.4 Vl 0.4

0 0 PS/PE 0.7 u u

0.2 0.2 0.2

00 o 0 100 200 300 400 500 o 0 100 200 300 400 500

PV Area. m2 PV Area, m2 PV Area, m2

I I I I I I I I I I I I 300 200 100 0 300 200 100 0 300 200 100 0

Thermal Area, m2 Thermal Area, m2 Thermal Area, m2

Phoenix

CT/Cpv 0 CT/Cpv 0 .~ .~

CT/Cpv 1.0 +' 1.0 +' 1.0 to to 2.0 ______ cr: 2.0~ cr:

0.8

1.0 ::1 +' 0.8 +' 0.8 2.0~ 4- 4-OJ

1.0~ QJ

1.0~ 0.6 <= 0.6 <: 0.6 QJ aJ

0.5~ 0.5 cc 0.5 cc I I

0.4 PS/PE 0.3 0 0.4 PS/PE = 0.5 0 0.4 = +' +'

I I PS/PE = 0.7 0.2 +' 0.2 +' 0.2 Vl Vl

0 0

0 u 0 u 0 0 0

PV Area, m2 PV Area, m2 PV Area, m2

I I I I I I i I I I I I 300 200 100 0 300 200 100 0 300 200 100 0

Thermal Area, m2 Thermal Area, m2 Thermal Area, m2

Figure 10-19. Economic Tradeoffs for SFD Side-by-Side Fossil Heating, DHW, and Absorption A/C System

10-36

•

•

•

•

•

• Table 10-11a

PV/Thermal Side-by-Side Systems Performance

SYSTEM II(a): PARALLEL HEAT PUMP SYSTEM

!

• I Annua 1 Usefu 1 Output

Region ApV ATC PV Thermal EUM ES LE (m2) (m2) (kWh) ( kWh) (kWh) (kWh) (kWh)

Boston 425 0 52556 0 59543 29955 82144

366 59 43460 16750 51930 22640 72750

299 126 35560 27040 49040 16575 68025

• 200 225 23705 38675 46275 7385 62600

Phoenix 425 0 83857 0 42208 46381 79685

366 59 69675 18070 33380 35975 67075

299 126 57000 20305 33445 25485 64960

200 225 38000 20870 36570 10305 64265

•

• 10-37

• Table 10-lIb

PV/Thermal Side-by-Side Systems Performance

SYSTEM II(b): FOSSIL HEATING/ABSORPTION COOLING

Annual Useful Output • Region ApV ATC PV Thermal EUM ES LE

(m2) (m2) (kWh) (kWh) (kWh) (kWh) (kWh)

Boston 425 0 ~1365 0 24745 38190 37920

366 59 43460 20350 25760 28230 40995

299 126 35560 36655 26270 21055 40780

200 225 23705 53905 27175 10745 40140 • Phoenix 425 0 82335 0 19660 63200 38795

366 59 69670 38350 20165 47500 42335

299 126 57000 67520 20560 35310 42250

200 225 38000 98265 22060 17950 42110

•

• 10-38

• Table lO-llc

PV/Thermal Side-by-Side Systems Performance

SYSTEM II(c): RANKINE DRIVEN HEAT PUMP

• Annual Useful Output

Region ApV ATe PV Thermal EUM ES LE (m2 ) (m2) (kWh) (kWh) (kWh) (kWh) (kWh)

Boston 425 0 52556 0 59543 29955 82144

• 366 59 43460 19585 49730 23855 69340

299 126 35560 36165 45575 18315 62820

200 225 23705 54035 41700 8190 57220

Phoenix 425 0 83857 0 42208 46381 79685

366 59 69670 32085 30560 37710 62520

299 126 57000 55320 28050 28115 56940

• 200 225 38000 77820 28430 11885 54550

• 10-39

• Table 10-12

Summary of Performance Results for PV/T

SOLAR DHW SYSTEMS IN SFD RESIDENCES • Thermal Therma 1 Excess Electric PV System DHW

PV Area Area Energy Therma 1 Load Output Supplied m2 m2 kWh kWh kWh kWh %

Phoenix 365.6 29.3 16,528 302 65,905 77 ,410 85.4

" 365.6 48.8 18,450 3,066 63,725 77,410 95.0

" 299.1 97.5 19,619 15,086 62,425 63,335 99.9 • Boston 365.6 29.3 8,142 0 75,835 48,290 34.4

" 365.6 48.8 11,368 0 72,495 48,290 47.8

" 299.1 97.5 15,775 53 67,950 39,510 66.2

Mi ami 365.6 29.3 13,157 0 64,735 33,005 79.7

" 365.5 48.8 15,639 0 62,000 33,005 94.4

•

• 10-40

• The economics of this system are evaluated using PV system costs similar to

those assumed previously with additional estimates for the thermal system layout for the detached single family homes. The thermal collectors located on the centrally located garage for the single family detached homes result in high piping system costs for the thermal distribution. Figure 10-20 summarizes the cost-to-b,enefit ratios for

• Boston and Phoenix.

•

•

•

Combined PV/Thermal Systems -- A combined PV/thermal system is also evaluated for a parallel heat pump system with utility feedback. Liquid cooled, single covered, flat plate collectors are assumed as described in Section 9. The collectors are situa­ted on the centrally located garage. Figure 10-21 presents the annual electrical and thermal system performance for several collector areas. Again, the PV output is pro­portional to the collector area, since the sellback mode allows for full utilization of the energy and the thermal output is a strong function of the demand. The thermal output is highest in the regions of high thermal demand, i.e., Boston. On the other hand, 100 m2 of collector area completely satisfies the thermal demand in regions of low thermal requirements, i.e., Phoenix. The annual performance for this system is listed in Table 10-13.

Thermal energy for solar cooling is not considered for these systems since the col­lector temperature is not high enough to power the units. The combined PV/T system cost-tobenefit ration variations are shown in Figure 10-22 for the system.

Townhouses, Apartments and Elderly Housing

Conceptual Design The three types of attached housing [Northern Townhouses and Southern Multiplex

(T&M), Garden Apartments (GA) and Housing for the Elderly (HE)] are evaluated to­gether. The conceptual designs for these units again consider roof-mounted shingle arrays for performance estimates. A summary of the maximum available array area and the corresponding peak power output at NOCT conditions for the different load center

10-41

a ...., <U

0::

...., 4-OJ ~ OJ

c::\ I a ...., ...... I 0 ....,

I VI -!:> a N u

•

r-. PHOENIX

1.2f 1.1 r

!

1.0

0.9 _ 7

0.8 1 0.7 # 0.6 L--__ ~ ,

25 50 75

Thermal Area, m2 100

BOSTON ._]

1.4 PSIPE " .3

a 1.3 ...... ...., <U

0:::

...., 1.2 ~".5 ...... 4-OJ ~ 1.1 OJ

<:0 I

a ...., 1.0 I ...., VI a u 0.9

0.8 25 50 75

Thermal Area, m2

Figure 10-20. Summary of Economic Performance for Side-by-Side PV/Thermal Domestic Hot Water System for Single Fami ly Detached Houses

• • •

100

•

•

70 [

60

50 ..c 3: ::;: ~

+' 40 ::::> 0.. +' ::::>

0 30

~

reS ::::> c ...... c 0 <:t: 20 r I

-I'> W

10 [ 0

0

• • • • PV OUTPUT THERMAL OUTPUT

70

60

Phoenix 50 ..c 3: ::;: ~

+' 40 ::::> 0.. +' ::::>

0

~ 30 reS ::::> c c

<:t: 20 Phoenix

/ 10

0 100 200 300 400 500 0 200 400 500

Collector Area, m2 Collector Area, m2

Figure 10-21. Combined PV/Thermal Collector System Performance Summary for SFD Houses

• Table 10-13

Combined PV/Thermal Systems Performance

SYSTEM III(a); PARALLEL HEAT PUMP SYSTEM

,

Annual I • Useful Output

Region Area PV Thermal EUM ES LE (m2) (kWh) (kWh) (kWh) (kWh) ( kWh)

Boston 130.2 7460 19605 62000 85 69370

260.4 18630 29045 51160 4620 65170 • 423.1 32850 36715 44260 15330 61780

Phoenix 130.2 13270 18405 53440 275 66435

260.4 31535 19305 40660 6805 65390

423.1 54340 19665 34650 24035 64950

•

• 10-44

• Boston

PL/PE = 0.3 PS/PE = 0.5 Ps/PE = 0.7

1.6 1.6 CT/CPV CT/Cpv

0 CT/Cpv

0 1.4 0 1.4 .~ .~ .~

2.~ ..... ..... ..... 2.~ res res res ex: ex: 1.2 ex: 1.2 ..... ..... ..... • 4- 1.0 4- 1.0 4-Q) Q) Q)

c: c: c: Q) Q) Q) co co 0.8 co 0.8 I I I

0 0 0 ..... ..... .....

I I 0.6 I 0.6 ..... ..... ..... Vl Vl Vl 0 0 0

u 0.4 u 0.4 u

0.2 0.2

0 0 0 0 0 100 200 300 400 0 100 200 300400

Collector Collector Collector

• Area, m2 Area, m2 Area, m2

Phoenix I PS/PE = 0.3 PSPE = 0.5 PS/PE = 0.7

1.6 1.6

1.4 CT/CpV

1.4 CT/CpV CT/Cpv

·0

2.0~ 0 .~

..... 1.2 ..... 1.2 res res ex: ex: ..... 1.0 ;<,:: 1 0 • 4- 4- • Q) Q) c: 0.8 a:; 0.8 Q)

co co I I

0 0.6 0 ..... ..... 0.6 I I ..... .....

Vl 0.4 ~ 0.4 0 u u

0.2 0.2

0 0 0 o 0 100 200 300 400 Collector Collector Collect~r

• Area, m2 Area, m2 Area, m

Economic Tradeof7s for SFD(s) RLC Combined Figure 10-22. Collector for All-Electric System

10-45

types is listed in Table 10-14. The table lists the maximum array area; however, parametric analyses for array area variations are completed for selected regions. ~

Table 10-14

Summary of Peak System Output for Available Roof Area

LOAD CENTER ARRAY TYPE AREA m2

GARDEN APARTMENTS 594 HOUSING FOR THE ELDERLY 1887 MULTIPLEX 275 TOWNHOUSE 263

PEAK POWER OUTPUT kW

52 165

24 23

Table 10-15 lists the number of units considered for each RLC type. The table also lists the nominal PV system characteristics, both the shingle array electrical network and the power conversion subsystem size. The number of parallel circuits listed again represent the maximum available roof area and parametric variations of parallel circuits provide the area variations for each RLC type. The conceptual de­sign assumes one centralized power conversion unit with the inverter size based on the nominal peak power rating and available standard sized units.

In the analysis, each RLC type unit has its own heat pump for space condi­tioning as shown in the schematic in Figure 10-23. In the case of side-by-side PVj thermal systems, one centralized storage system is assumed also, as shown in Fig­ure 10-23. The space conditioning loads are presented in Section 5 for all the RLC types.

The conceptual design for each RLC type must consider the equitable distri­bution of energy and savings from the PV system for each unit owner. This equitable distribution is not as straightforward as might be expected, especially in the case of the solar array output greater than the total loss for a RLC over a given time period.

Cost Estimates Cost estimates for the Townhouse, Garden Apartment and Housing for the Elderly

are made following the same approach as described for the single family detached houses.

10-46

•

•

•

•

;-, o I

-I'>

"

•

RESIDENTIAL UNITS

NO.

5

4

4

8

154

• • Table 10-15

Residential Load Center - Block IV PV Shingle Modules

1

TYPE PV ARRAY UNIT MODULES

AREA SERIES PARALLEL m2 V

DESCRIPTION NO. NO. VOLTS

DETACHED HOMES 34 64 425 248

ROW HOUSE 28 48 263 204

MULTIPLEX 33 37 275 277

GARDEN APARTMENTS 23 88 395 168

HOUSING FOR ELDERLY 25 386 1885 183

• •

, I POWER I ARRAY NOCT CONVERSION I PARAMETERS SUBSYSTEM

SIZE

I P kVA

AMPS kW

150 37 50

113 23 30

87 24 30

206 35 50

904 165 200

t-' 0 I ..,.

CD

•

i2R

X ) Ire I~, ~')fl-fil( HomJI Ie 90 01)11 lfi n x) ~ I n R)

PV - ONLY HVAC

CONF I GURATION

JAL JRL Ie n n n 1)IIIIIIC-lrR

Figure 10-23

STORAGE

SIDE-BY-SIDE PV/THER~V\L

CONFIGURATION

Multi-Family Heating and Cooling System Distribution

• • • •

•

•

•

•

•

The primary differences are in the fixed costs accounting for the different number of units assumed for each RLC type. Table 10-16 shows these variations. The fixed and variable portions of the power conversion subsystem also varied for the nomi­nal size range of equipment used for each RLC type. Table 10-17 summarizes all of the costs. The SFD and Garden Apartments costs are the same, except for the additional metering costs for the three additional units serviced in the Garden Apartment design.

Table 10-16

Electrical Equipment Cost Estimates

COST ELEMENT

ARRAY JUNCTION BOXES

DISTRIBUTION PANELS

MISCELLANEOUS HARDWARE

WIRING

BUSBARS

TOTAL MATERIALS

LABOR

TOWNHOUSE AND

MULTIPLEX

66

132

132

794

310

$1434

$ 700

GARDEN APARTMENT

132

198

132

1173

526

$2161

$1152

HOUSING FOR THE ELDERL Y

397

397

529

3570

2358

$7251

$3148

In summary, the systems costs for each RLC type are represented as:

GARDEN APARTMENTS (8 UNITS) I = $103.76/m2 + $90.88/kW + $10,014

TOWNHOUSE OR MULTIPLEX (4 UNITS) I = $103.76/m2 + $150.88/kW + $5,544

HOUSING FOR THE ELDERLY I = $103.76/m2 + $61.39/kW + $52,609

Performance Results

The PV system without storage is evaluated for each of the RLC types in selected locations. In addition, a side-by-side PV/thermal system is evaluated for the Garden Apartment RLC. All of the loads assumed for each of the RLC types are discussed in

Sections 5 and 6. 10-49

t-' o I

U1 o

Table 10-17. Summary of System Cost Estimates

TOImHOUSE & SINGLE FAMILY DETACHED MULTIPLEX GARDEN APTS.

TOTAL COST TOTAL COST UNIT UNIT Single

COST ELEMENTS COST Multiplex Townhouse COST Family Garden Apt. PV ARR'AY $81.10/m'l. $22303 $21329 $81. 1D/m'l. $34,468 $32,116

SOLAR ARRAY $22.66/i $22', 66/m2 INSTALLATION $ 6232 $ 5960 $ 9,630 $ 8,973

(INCL. CREDIT)

POWER CoNDITION- $2220 + $ 6744 $ 6744 $4316.64+ ING SUBSYSTEM $150.8o/kw $90. 88/k.w $ 8,861 $ 8,861

ELECTRICAL EQUIPMENT $1434 $ 1434 $ 1434 $2161 $ 2,161 $ 2,161

ELECTRICAL SYSTHI INSTALLATION LABOR $ 700 $ 700 $700 $1152 $ 1 ,152 $ 1,152

METERS $ 298 $1190 $ 1190 $29B " $ 1,490 $ 2,384

TOTAL $38603 $37357 $57,762 • $55,647

"-- _~L

NOTES 1. 1980$ 2. Prices Include (2) 15% Markup Estimates

• • •

HOUSING FOR THE ELDERLY i

UNIT TOTAL COST COST $81.10/m2 $153,036

$22. 66/m 2 $ 42,759

$11 ,660+ $ 23,938 $61.39/k.w

$7251 $ 7,251

$3148 $ 3,148

$198.38 $ 30,550 I i

$260,683

• •

•

•

•

•

•

PV System Without Storage -- Figure 10-24 shows the monthly performance for the Northern Townhouse and the Southern Multiplex at selected sites for the given array area. Relatively good load matches are seen in the Southern systems with system output greater than 75% of the total building loads. In the Northern installations, system output provides over 50% of the building loads. Figures 10-25 and 10-26 show similar monthly performance for the Garden Apartment and the Housing for the Elderly in two locations .

The total load for the Housing for the Elderly is approximately 1,400 MWh and the system output from the available roof area varies from only 16% in Boston to ap­proximately 24% in Phoenix. In addition, practically all the energy is applied direct­ly to the load. An additional 700 m2 roof area is available, but a more complex array electrical circuit layout would be required.

Table 10-18 summarizes all of the performance data for the RLC types.

Using the system cost estimates described previously, levelized annual costs and benefits are calculated for the array area variations for each RLC type. Figure 10-27 summarizes these results. The performance trends are similar to the single family detached results. In the Housing for the Elderly design, most of the system output is used directly and, therefore, the sellback rate is not a factor.

Side-by-Side PV/Thermal Systems -- Several side-by-side PV/thermal systems are studied for the Garden Apartment RLC and compared to the Single Family Detached RLC type. In general, the performance and economic results and trends are similar to the SFD results. Table 10-19 lists the performance results for the parallel heat pump sys­tem, system configuration II(a), varying the PV and thermal collector areas. Again, varying the thermal systems costs as a function of the PV system costs used previously shows that approximately equal PV system costs and thermal system costs on a $/m2 basis are required for economic viability. Since the results are similar to the SFD results, no additional RLC types are evaluated.

PV/Thermal Hot Water Heating System -- A solar domestic hot water system is evaluated for the garden apartments and compared to the single family detached results. Table 10-20 summarizes the performance results for Boston and Phoenix. Several thermal collector/PV array areas are considered.

10-51

.<= 10 ROWHOUSE (263 m2) § 10 t\ ROWHOUSE (263 m2) 3: BOSTON r~ADISON :E :E ~

LOAD (63.6 MWh) ~

~LOAD (69.8 MWh) >- >-(!:l (!:l cr:: cr:: w w :z:: :z:: w 5 w 5 >- >-...J ...J I I l- I-z: :z:: 0 0 :E :E

or "- PV SYSTEM PV SYSTEM

OUTPUT (31.9 MWh) OUTPUT (35.4 MWh) o I , , I • I ! I I

J

MULTIPLEX (275 m2) 10 T MULTIPLEX (275 m2)

....... .<= PHOENIX FT. WORTH 0 3: .<= :E

PV SYSTEM OUTPUT (54. 7 r~Wh) 3: I :E

;- LOAD (59.2 1<1Wh) 01 f'-> ~

>- ~

(!:l >-cr:: (!:l w cr:: z: 5 w 5 w :z:: >- w ...J >-I ...J l- I :z:: I-0

( 62. 7 r'1Wh) :z:: LpV SYSTEM OUTPUT (44.2 MWh) :E 0

:E

Figure 10-24

Monthly Performance of PV Only System Without Storage for Single Family Attached

• • • • •

• •

15 T I :s: ::E 10 "' >-

(!) a::: w z w

>-5 ....J

I .-...... Z 0 0 I ::E U1 w

0

• • BOSTON 15 PHOENIX

T PV SYSTEM OUTPUT (1l2.8MWh)

\ I

LOAD (93. 1 r~Wh) 3; ::E

( "' 10 >-(!) a::: w z w

>-5 ....J

t ~LOAD (97.9 MWh) I .-Z 0

PV SYSTEM ::E

OUTPUT (47.0 MWh)

0

Figure 10-25

Monthly Performance of PV Only System Without Storage for Garden Apartments (396 m2)

•

-C :3 ::::

n

>-Ul 0:: w z w

>--I :::c I-

...... Z a a I ::::

1I1 -I=:-

•

201 BOSTON

200 1 PHOENIX

LOAD (1400 MWh) LOAD (l471 t~Wh)

150

-C :;:: ::E

n

100 >-Ul 100 0:: w :z: w

>--I :::c l-

50 z

50 + PV SYSTEM OUTPUT a ::::

PV SYSTEM OUTPUT (364 ~lWh)

(228 MWh) ~ ~-----.

o L I J F I M IA I M I J IJ I A Is 10 I N I D I 0

•

Figure 10-26

Monthly Performance of PV Only System Without Storage for Home for the Elderly (1887 m2)

• • •

•

• BUILDING TYPE

Rowhouse (4 Unit)

"

Multiplex (4 Unit) • "

Garden Apt. (8 Units)

"

• Elderly Apt.

•

Table 10-18

Summary of System Performance for Different RLC'S -All Electric System Without Storage

PV'AREA NET SYS . UTILITY FEEDBACK OUTPUT MAKEUP ENERGY

CITY Apv Eo Eum Es m2 kWh kWh kWh

Boston 263 31913 47124 15463 197 23664 48694 8784

131 15321 51258 3004

Madison 263 35351 51516 17063

Phoenix 275 54747 34230 26235 208 41129 36596 14984

134 25854 41459 4591

Ft. Worth 275 44224 36016 21087

Phoenix 594 108197 49739 60047 445 83117 52536 37764 396 75326 54378 31815 297 56392 57850 16353

198 36407 65936 4454

Boston 594 71153 64394 42481

396 46965 67708 21607

Phoenix 1887 363674 1110501 2338 1417 273714 1198191 68

943 180453 1291383 0

Boston 1887 228027 1173996 2142

10-55

ELECTRICAL LOAD

Le kWh

63574 63574

63574

69804

62742 62742

62742

59153

97889 97889 97889 97889

97889

93066

93066

1471837 1471837

1471837

1399881

1.2 1.4 ROWHOUSE 0 GARDEN APT. 0 BOSTON ~ 1.0 .....

1.2 PS/PE PHOENIX I--ct:

PS/PE ct: c:: c::

- 0.3 ~ 0.8 ~0.3

I-- 1.0 ~0.5 ..... lL. lL. W ~~ ::: 0.5 w

0.7 z 0.7 z 0.8 ~ 0.6 w

co 0 0 I-- 0.4 I--

0.6 I-- I--V) (/) 0 0

0 u 0 u

0 100 200 300 400 500 100 200 300 400

AREA, m 2 AREA, m 2

HOME FOR THE ELDERLY MULTIPLEX 1.0 PHOENIX 1.2 T PHOENIX 0 ..... ..... 0

0 I-- ..... 1.0 + PS/PE I ~ 0.8 I--

tn ~ m I--

I--t:;:: 0.6

"---.....

0.8 t ____ 0.3 w lL.

~_0.5 z w w z

0.7 co 0.4 w co 0.6

0 I-- 0

I--t:; 0.2 I-- 0.4 0 (/) ..;::.. , u 0

U 0 0 0 0 100 200 300 400

Figure 10-27

Summary of Cost to Benefit Ratio for Residential Load Centers

• • • • •

• Table 10-19

PV/Thermal Side-by-Side Systems Performance for Garden Apartments

SYSTEM lIra):

Annual Useful Output -I

Apv ATC PV Thermal EUM ES LE

• Region (m2) (m2) (kWh) (kWh) (kWh) (kWh) (kWh)

Boston 396 0 47104 0 67568 21608 93064

324 67 33960 18424 60792 24080 81672

252 147 24744 28016 58328 7216 75864

180 214 15488 33672 59424 2192 72728

Phoenix 396 0 75280 0 54424 31816 97888

324 67 56976 16160 41776 22328 76424

252 147 42392 27552 44096 22328 74544

• 180 214 22712 27576 50440 3792 74360 ,_._-- _ . -

•

• 10-57

Table 10-20

Summary of Performance Results for PV/T Solar DHW Systems in Garden Apartments II(d)

,~--_._ ..

j

Useful PV PV Thermal Therma 1 Excess Electric System

Area Area Energy Thermal Load Output DHW m2 m2 kWh kWh kWh kWh Supplied (%)

Boston 324 47 12,477 -0- 83,496 33,968 37.2

" 252 109 19,914 59 75,720 24,744 59.2

" 180 203 25,467 593 69,936 15,496 75.4 ~---.- --

Phoenix 324 47 24,143 715 78,040 56,976 88.3

" 252 209 27,127 15,231 73,448 42,392 98.4

" 180 203 27,816 41,629 73,592 27,712 100.0 ._--- -------~----.. ---.. ---.-.. - .. -~~--.---.. -- .-.------.. ~ - ---------"'-----0

The results again are similar to the single family detached RLC in the regions. Most of the hot water requirements are met in Phoenix with moderate amounts of the load met in Boston. Note the higher thermal collector areas for the garden apartments be­cause of the higher thermal laods ,due to the increased unit density. Figure 10-28

summarizes the economic performance for the system. Minimum cost-to-benefit ratios exist below 100 m2 of thermal array area. Similar to the SFO RLC, the system shows economic viability in Phoenix.

Load Sensitivity Studies -- Parametric anayses are also performed to determine the effects of load variation on system perform3nce for single family detached houses and garden apartment RLC types. The approach to the load sensitivity evaluations is to maintain the same profile amplitude and shape as used in the baseline studies, but to shift the peaks. This, in effect, addresses households operating on different schedules and allows assessment of different utility feedback and utility make-up re­quirements.

The basic daily profile shown in Figure 5-6 is altered by shifts of 8 and 16 hours. Table 10-21 summarizes the results of these variations for a group of single family homes and garden apartments in several locations. The variations in the utility make-up requirement and the energy sold back to the utility for the profile shifts are noted.

10-58

•

•

•

•

•

•

•

•

.6L-----~5~0-----..~---,~-----2~00

Thermal Area, m2

BOSTON

0 .~

+'

'" cr:: +'

4-Q) <= Q)

co I

0 +'

I +' V1 0 Ll

.8 50 100 150 200

Thermal Area, m2

Figure 10-28. Summary of Economic Performance for Side-by-Side PV/Thermal Domestic Hot Water System on Garden Apartments

10-59

• Table 10-21

Summary of Load Profile Variation Effects on Performance

LOCATION PV UTILITY SELLBACK ELECTRICAL

AREA, 2 MAKE-UP kWh LOAD m kWh •

Phoenix, SFR, Normal Load 425.4 42,048 44,355 79,685 1\ " 8 hr. Shifted 1\ 41,498 43,804 79,685

16 u " II 49,827 52,133 79,685 . Boston, SFR, Normal Load 425.4 59,297 29,244 82,144

" " 8 hr. Shifted " 58,293 28,240 " 16 II II " 65,150 35,097 II

Miami, SFR, Normal Load 425.4 41 ,181 30,063 75,178 • II II 8 hr. Shifted II 39,674 28,556 " II II 16 II " 1\ 48~270 37,152 "

Phoenix, GA Normal Load 395.7 53,990 26,193 97,889

" II 8 hr. Shifted II 53,076 25,279 " " " 16 II " " 64,053 36,256 "

Boston, GA, Normal Load " 66,841 19,591 93,066 II " 8 hr. Shifted " 65,773 18,523 "

16 " " " 74,848 27,598 " •

• 10-60

•

•

•

•

•

Mobile Home

Conceptual Design The mobile home park is the one type of RLC type which has different charac­

teristics than the previously discussed RLC types. The first unique characteristic is the lack of available roof area for the PV array. The dispersion of mobile home units

makes it impractical to roof-mount a centralized array approach for a RLC. In addi­tion, if a mobile home is a part of a centralized roof array system, it may eliminate the mobility of the unit. The argument for not roof mounting the array does not,

however, eliminate a roof-mounted PV array for a single unit. But this case does not fall into the RLC category. Thus, a centralized ground-mounted array is considered

for the mobile home park. Even this design appro~ch can be criticized due to the

value of the land to the mobile home park owner; however, a centralized flat plate PV system is designed and evaluated for a mobile home park. Figure 10-29 provides a

layout of a 100-unit mobile home park with 17,330 m2 of land area reserved for the PV array. The site plan also indicates the impracticality of imposing all homes to be

south facing for a roof-mounted PV array. Forty-nine percent of all mobile homes are

grouped on sites of 6 or more homes. For this study, a 50-unit mobile home park is ultimately evaluated.

The PV collector selected for use in the array layout is the Arco Solar module 16-2000. At the nominal operating cell temperature (NOCT) of 450 C (Ref. Arco Solar), the module maximum power point characteristics are 14.6 Vdc and 2.05 Amps, which cor­respond to 30 Watts of peak power under 100 mW/cm2 of irradiation. The collector

field consists of 10 rows covering approximately 7,155 m2 and containing 9,600 mod­ules .

The conceptual field arrangement is based upon a 2.44 m x 6.1 m flat array mounted on a central wooden post driven into the ground. This is a concept developed

by Bechtel and Motorola in studies for Sandia Labs on low cost structural arrange­

ments. An array consists of five 2.44 m x 1.2 m panels connected in series, with each

panel made up of eight .3 m x 1.2 mArco Solar modules wired in parallel. The concep­tual electrical and mechanical build-up is illustrated in Figure 10-30. Table 10-22 lists the build-up of the array field and field characteristics. Six arrays are wired

in series to form a branch circuit, and are physically arranged in two rows of three

arrays each to loop the plus and minus branch terminations to a central aisle. Ten

10-61

+-+----1-+

I I

/

1 I

i I

I ! II , ! I

i !

i I I I' ! I I

~I§II ! ,I

! ! / ! I i

II ! I

I

I I

II / I , I I, I I

1 -J"!.-f --,S'71 + ----------- J

r 10-62

..

I/l 1

-'< '­ttl

"---ClJ E o :r: ClJ ~

.~

0) N , o .---<

ClJ '­=> 0> .~

LL

•

•

•

•

•

• MODULE

I-~------+;J

l--' _ BRANCH CIRCUIT o &. 8 Row Jumpers, w 2 Inter-Row Jumpers

~ARAAY: :-: -ir

.3 m

• • PANEL

(14 Jumpers) ARRAY

(8 Jumpers)

(I- Module r-

(~ C~ (r-

C (-

(

Main/ Bus

-~

) 1------6.1 ml---1 -) -

r-Q)

) ~

0.. 1. .61 m

-)

SUBFIELD

+

uu_~_ I- _. --~

1.--_1 L--[ __

,-------,I ,<--_--' ~.8 ~

4 JB for 2 Btanch Each 1 JB for 2 Branch & Main Bus

40 Jumpers Branch to Bus

Building lO'x12'

"0

Q) -.... .Q

'" V'l

• • ARRAY ROW SPACING

It r( J I 1.2 m

300 1 ! I J , ' , ' , ' J '

~4m~ 4.6 m

FIELD

-j f-- --j I-.3 m 6.1 m

Figure 10-30. Mobile Home Park Design Layout Concept

Table 10-22

Array Characteristics Field

Array Segment Current Voltage Power Width x Depth Amps V kW m --

Module 2.05 14.2 .0291 1.2 x .3

8 Modules = Pane 1 16.4 14.2 .233 1.2 x 2.4

5 Pane 1 s = Array 16.4 71 1.164 6.1 x 2.1

6 Arrays = Branch 16.4 426 6.934 18.9 x 6.7

10 Branches = Subfield 164 426 69.84 39.6 x 43.3

4 Subfields = Field 656 426 279.4 165.2 x 43.3

branch circuits arranged in ten rows of arrays make up a subfield, and four subfields

make up the total field for the design. The selected row-to-row pitch distance of

fifteen feet permits over six hours of non-shadowed row-to-row operation at the winter solstice with an array tilt of 300 at a latitude of 300 . The parallel wiring of

modules in the panels minimizes any minor end-of-day row-to-row shadow obscura-tions.

The array field would occupy a land area of 165 m wide x 433 m deep which

•

•

•

includes a central 6.1 m aisle for power control and conversion equipment. This is • well within the 50-unit mobile home park area allocation of 172 m x 50 m. The

field will produce a peak power of 279 kW at 426 Vdc under the JPL-defined Standard Operating Conditions. An inverter rating of 300 kW has been selected to allow for collection of power above the field SOC rating when the combination of insolation, temperature and wind permits, and to use what might be more typical of an inverter

rating value. At the expected power levels, a three-phase system output at 480 Vac

is designed with distribution to small groups of 5 to 6 homes through local single phase transformers at normal residential levels of 240/120 Vac. The three-phase

field and inverter output provides better system efficiency and power quality than single phase systems used at lower power ratings.

10-64

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•

•

•

Cost Estimates Cost estimates have been developed for the conceptual system based upon the

system hardware required, as specified in Figure 10-30. It has been assumed that a mobile home park consists of rental spaces and that the utility distribution net­work, including the park main three-phase transformer, local single phase trans­

formers, main metering, and individual site metering, if required, are all part of

the park and utility normal design and costs without the presence of a photovoltaic

system. Therefore, only the PV system costs to the point of termination on the 480 Vac distribution system are estimated for evaluation purposes. To permit analyses

of 1 arger and smaller fields and establ ish recommended sizing based upon parametric

variations of cost elements, such as module costs and utility feedback rates, total costs have been broken down into fixed and size variable portions similar to pre­

vious costing approaches. Table 10-23 lists the cost elements and associated costs. Module costs are again based upon the DOE cost goal. Array structural

costs are based upon Bechtel low cost structure study estimates. Inverter costs are based upon reasonable extrapolation of the costs established for other RLC concepts previously developed. Structural installations and standard field

hardware are based upon the Building Cost File handbook, and specialized hardware

such as the branch circuit diode isolation box are based upon recent price quotes

for the commercial electrical/electronic hardware required.

The total system price is expressed as:

I = $122.88/m2 + $68.89/kW + $20,804

A PV-battery system is also cos ted for comparison to the all PV system by making the following modifications to the estimates of Table 10-23:

•

•

•

Reduce the inverter size to 250 kW

Remove the isolation box related costs

Replace the pre-fab control building costs with a fixed and variable (as

a function of battery capacity) cost estimate for a building sized to

house the selected battery capacity--$3,352 FIXED + $4.96/kWh

10-65

Tab 1 e 10-23

Cost Estimates for 50-Unit Mobile Home Park Photovoltaic System

Cost Element

PV Modules - 9600

$72.49/m2

Array Structure Installed - 240

$37.47/m2

Module Installation

$4.27/m2

Electrical Field Hardware & Installation

$8.65/m2

Prefab Control Building 3 m x 3.7 m, Fixed

Installed in Slab

Inverter, 300 kW, Auto. w/Pwr. Trk.

$11,660 Fixed + $61.39/kW

Isolation Box

$2,811 Fixed + $7.50/kW

Equipment Misc. Controls, Hardware

and Bldg. Installation, Fixed

10-66

- - . -T-

Cost

$258,617

133,663

15,240

30,848

1,676

30,077

5,060

6,657

$481,838

•

•

•

•

•

•

•

•

•

•

• Add shunt/isolation control equipment costs of $5,736 FIXED + $16.29/kW

• Add battery installation and equipment costs of $4,426 FIXED + $4.17/kWh

• Add battery charger fixed cost of $28,000

• Add cost of batteries (varied parametrically)

The total system price is then expressed as

ISATTERY = $122.88/m2 = $77.68/kW + $9.13/kWh + 57,831 + $/kWh

Performance Results Several performance evaluations of the flat plate array system for the 50-

unit mobile home park are made. The analysis are for the Southwest region (Phoe­nix) to evaluate performance in a high isolation area. The first system assumes a

grid connected feedback arrangement. The performance results for this system at

various field array sizes are listed in Table 10-24. Some of the same field array

sizes are then evaluated assuming a grid connected system with battery storage. These results are summarized in Table 10-25 for various battery storage capacities.

--

Region

Table 10-24

PV-Only Systems Performance System for All-Electric Loads with Feedback for the Mobile Home RLC

- .• _." __ "c=",". ""-.C~~;O·--_-T·~"··Y __ --"-.·'

Net Array System Ut i 1 ity Feedback Electrical

Area Output Make-up Energy Load ApV EO EUM ES LE (m2) (kWh) (kWh) (kWh) (kWh)

Phoenix 892 153,168 549,931 7,459 695,640

1,784 317,144 447,678 69,183 695,640 3,567 640,452 371,385 316,197 695,640 5,351 957,566 343,615 605,541 695,640

10-67

...... o I

0"> OJ

1-

•

Table 10-25

Summary Performance of PV System with Battery Storage for the Mobile Home RLC

----~-.-,-"' .. ---~ "--

Battery I "- ! .. --.-.~--~~-

Net I , , Array System Utility Battery Battery Annu a 1 Region I Area Capacity Output Make-up Charge Discharge Excess

(m2) (kWh) (kWh) (kWh) (kWh) (kWh) (kWh)

Phoenix 1,784 700 297,422 389,218 193 . 1,784 1,440 298,510 387,130 207

I

3,567 700 475,309 220,331 282,876 225,481 57,744 I 3,567 1,440 537,229 158,411 329,565 284,732 17,852 I 3,567 3,000 547,478 148,162 335,104 293,599 9,937

I I

5,351 700 517,606 178,034 331,370 236,999 198,236 5,351 1,440 632,250 63,389 445,061 350,322 132,834 5,351

I 3,000 674,382 I 21,257 89,731

: "

I I -------

• • •

I --Load

(kWh)

695,640

I i ___ e •

•

• As mentioned in Section 9, the economics for the mobile home park assumes

commercial ownership. The appropriate economic parameters as listed in Table 9-2 are thus used to determine the levelized annual benefits and costs of the system.

Figure 10-31 summarizes the cost-to-benefit ratio for the mobile home park as a function of sellback rate and array area. The commercial ownership fixed charge rate of 14% tends to detract from the overall system economic viability in the high insolation area. Similar types of results are shown in Figure 10-32 for the system

~ with battery storage. Several battery costs, battery capacity and field sizes are shown parametrically in the figure. Even at zero battery costs, these systems have cost-to-benefit ratios greater than 1.

•

•

•

The mobile home park PV system could also be conceptualized as displacing stand alone, diesel generated power for the park. Assuming an arbitrary 12% in­

crease in cost of the stand alone generated electricity, the cost-to-benefit ratios are recalculated for the system with battery storage with the results shown in Figure 10-33.

a .~ ...., ttl 3 C<: ...., . PS/PE .~

4- 2 \ <1l

~8:~ 0: <1l

o::l I a ...., I ....,

0 V1 0 0 1 2 3 4 5 6 u

Figure 10-31. Economic Results for Mobile Home Feedback System

la-69

BAT. CAP = 3000 k\~h BAT. CAP = 1440 kWh BAT. CAP = 700 kl-Jh 0 5

0 5 5

0 .~ Bat. Cost .~ .~

+-> --.i!kWh +-> +-> ro ro

~4 CY: 4 IX 4 +-> +-> Bat. Cost +-> .~

4- 3 100~ 4- 3 $(kWh '~ 3 Bat. Cost (l) (l) <= <= <= $/k\~h (l) (l)

1B8~ (l) co co co 150 I 2 50 ___ I 2 I 2

0 0 1~8?-~ +-> 50 ---------=::: 0 +-> +-> I I o - I

+-> 0 +-> t: 1 Vl 1 Vl 0 0 0 u u u

L

0 1 2 3 4 5 0 1 2 3 4 5 0 2 3 4 5

COLLECTOR AREA, t03 m 2 COLLECTOR AREA, 103 m2 COLLECTOR AREA, 103 m2

COLLECTOR AREA = 5137 m2 COLLECTOR AREA = 3567 m2 COLLECTOR AREA = 1784 m2

t-' 5 5 0 0 0

~ 4~ Bat. Cost I

.~ .~

" +-> +> _$/kWh 0 ro 4 ro 4 CY: Bat. Cost a:: Bat. Cost / 150 +-> $/kWh +> $/kWh 4- 3 4- 3 ~ 3 (l) (l) 150 <= <=

~1B8 <= (l)

(l) (l) ~100 co co 2 co 2 I

I ::::.... ::...----- 50 I . 50 0 0 ~ - 0

0 +-> +> +-> ---- 0

I I I t: , I 0 +> +->

Vl Vl 0 0 0 u

u u

0 0 0 0 1 2 3 4 5 0 2 3 4 5 0 1 2 3 4 5

BATTERY CAPACITY, r~wh BATTERY CAPACITY, Mwh BATTERY CAPACITY, Mwh

Figure 10-32. Economic Tradeoffs for the Grid Connected Mobile Home Park System with Battery Storage'in Phoenix

• • • • •

• • • • • BAT. CAPACITY 3000 k\~h BAT. CAPACITY 1440 kWh BAT. CAPACITY 700 kWh

5 Bat. Cost

5 0 5 0 0 .~

.~

$/kWh .~ +-'

+-' +-' ro ro 4 ro 4 cr: 4 cr: cr: Bat. Cost 150 +-' +-' +-' $LkoWb .~

.~

3 .~

3 4- 3 4-

100~ 4- <U

<U <U <: l Bat. Cost <: <: <U <U <U 150 ~ 2 $I k\~h ~ 2 50~ ~ 2 100~::: .8 I I 0 --S 19t- ~ +-' 50- I I

0 - I +-' +-' 1 +-' 1 0 !/) 1 0 !/) !/) 0 0 0 u u u

0 0 0 o 1 2 3 4 COLLECTOR AREA, 103m2 5 0 1 2 3 4

COLLECTOR AREA 103m2 5 o 1 2 3 ~ COLLECTOR AREA, 10 m2 5

COLLECTOR AREA = 5351 m2 COLLECTOR AREA = 3567 m2 COLLECTOR AREA = 1784 m2

....... 5 5 5 0 0 0 0 I .~ .~ .~ Bat. Cost

'-J +-' +-' +-' I-' ro 4 ttl 4 ttl 4 -.iLk\~h c:r: er:: cr:

+-' +-' Bat. Cost +-'

~~:: .~ Bat. Cost 4- .~

4- 3 3 $Lk.Wh 4- 3 <U $/kWh ~ <: <U <:

<U 150 <U ~150 <JJ ~ ~100 b ~

I 2 2 ~100 I 2 0 0 +-' :::::::::.:: -- 5 0 "'i' ===--- 50 +-'

I I +-' 0 +-' -- 0 +-' 0 !/) !/) !/) 1 0 0 0 u u u

0 0 0 0 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5

BATTERY CAPACITY, r"wh BATTERY CAPACITY, Mwh BATTERY CAPACITY, i-lwh

Figure 10-33. Economi c Tradeoffs for the Stand Alone i10bil e Home Park System in Phoen i x

• SECTION 11

RLC LEGAL/INSTITUTIONAL ISSUES

General Electric requested D. Woodson of the University of Florida, Center for Governmental Responsibility to review the legal and institutional issues related

• to residential load centers. Mr. Woodson completed a thorough review of the key issues and provided a detailed report of his review. This report is included as

Appendix C, Volume 2 of this report. Table 11-1 provides a brief summary outline of the topics covered in the report.

•

•

• 11-1

Table 11-1

Outline of Legal/Institutional Issues for Residential Load Center Photovoltaic Systems

Outline

I. Introduction

A. Description of ownership concepts to be discussed.

B. Discussion of the advantages and disadvantages of each ownership concept.

II. Condominium Type Ownership

A. An analysis of existing condominium law: evaluation of the legal aspects of common elements (i.e., swimming pool, parking lot, shrubbery, etc.) and comparisons to the establishment of a residential load center.

B. Discussion on the legal/institutional factors to be encountered by the condominium owner.

1. Financing

•

•

(a) The ability to pay for the load center via mortgage payments and • deduct interest payments from taxes.

(b) Government incentives - loans, credits, deductions.

2. Property value increases will raise property taxes, but will be com­pensated by life cycle cost and higher resale value. States with property tax exemptions are noted.

3. Insurance

(a) Insurance, maintenance, and operation expenses will be administered through the condominium association.

(b) Individual protection, assuming general safety standards are met, • will be included in home owner's policy.

4. Access to the Sun

(a) Problem is minimized by nature of centralized system and strong public policy to encourage the use of solar energy.

(b) Protection via public nuisance law.

(c) Restrictive covenants and expressed easements.

11-2

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•

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•

Table 11-1 (Cont'd.)

Outline of Legal/Institutional Issues for Residential Load Center Photovoltaic Systems

C. Utility Issues

1. Back up power

2. Energy se 11 back

3. PUC regulations

D. Incentives for Builder/Developers to construct condominiums adaptable to the residential load centers.

III. Commercial Ownership - Mobile Homes

A. Standards under the National Mobile Home Construction and Safety Act.

B. Financing initial solar installments.

1. Incentives vi a tax breaks.

2. Loans to the commercial owners similar to those provided by the REA.

C. Utility Issues

IV. The Role of the Utilities - Ownership of the Residential Load Center

A. Service and rate discrimination.

B. Scope of the PUC and its consequences for solar users.

C. Utility participation in the solar market.

11-3

•

•

SECTION 12 BUILDING CODE REVIEW

Summary

There are approximately 40,000 building code jurisdictions in the United States. However over 70% of them use either intact, or somewhat modified, one of the three model codes -- the Uniform Building Code (published by the International Conference of Building Officials - ICBO); the Standard Building Code (published by the Southern Building Code Congress International - SBCCl); or the Basic Building Code (published by the Building Officials Conference of America - BOCA). Officials of the three model code writing bodies meet under the aegis of another organization, known as Congress of Building Administrators - COBA. Each of these model code bodies also publishes a series of mechanical and plumbing codes, along with a few specialty codes dealing with housing, dangerous buildings, signs, security, etc. Outside

• these three major codes there is the National Electric Code to deal with electrical matters. Solar codes have been slowly woven into the three model codes, as well as

•

•

being promulgated as separate code documents.

Building Code Analysis for Residential Load Centers

Model Code Characteristics Building codes are enforced under the police power to regulate health and

welfare. The Uniform Building Code's purpose is " ... to provide minimum standards to safeguard life or limb, health, property and public welfare by regulating and con­trolling the design, construction, quality of materials, use and occupancy, location and maintenance of all buildings and structures within this jurisdiction and certain equipment specifically regulated herein." Not only does it deal with construction issues, building size, building materials, and building design; but it involves such

matters as security, protection of passerS-by, storage of hazardous materials, pro­tection from rodents and pests, disposal of rainwater, and all sorts of other mat­ters which at first sight do not directly bear upon the issue of health and welfare. In general, as society becomes more complex, building codes extend their coverage to more and more issues. Two recent additions of note are regulations with regard to handicapped persons, and regulations on the consumption of energy.

12-1

The three model codes have a similar structure, but vary with regard to the detail contained within the actual code document. The Uniform Building Code re­prints some of the most important standards which are only referenced in the BOCA code. The UBC is therefore a kind of building encyclopedia, which makes it both ex­tremely valuable and very difficult to work with. The BOCA code, on the other hand, appears to be simpler, but contains many hidden requirements which are buried in the documents referenced in the back of the code and thereby included as part of the code itself. The Standard Building Code lands in between, but resembles the BOCA code more than it does the Uniform Building Code. It is the most "old-fashioned" of the three.

The first part of the code discusses the legal aspects, jncluding measures to be taken if the problem at hand is not covered by the code. The second part is an important set of definitions. One is always referring to these definitions to see exactly what is meant by such things as cellars and basements, courts, yards, etc., since the exact definition is often very important in clarifying what is numerically stated later in the code. There is also a section which classifies all buildings by their use or occupancy. Included in this classification are miscellaneous re­quirements unique to each kind of occupancy. The codes vary a good deal in how much detail they get into at this point. The UBC, for instanc€, has long and detailed requirements for each occupancy type; while the SBC briefly defines each classifica­tion and refers the user elsewhere for details.

Next are the requi rements based upon construct ion type. These generally 1 i st five or six building types, ranging from fire-resistive Type I buildings through Type 5 or 6 wood-frame residential buildings. Each of these building types is de-

•

•

•

fined with regard to the fire rating of each component of the construction. This • of course has a very important cost implication for the builder.

The key element in these first two sections is a table (or series of tables) which relates the occupancy type to the type of construction. The table will say, for instance, that an apartment house built with one-hour wood-frame construction can have an area of only 10,500 sq. ft., and can be only three stories high. If built with Type I construction, it can have an unlimited height and unlimited area. Thus, the height and size of the building determines the expense needed to construct • it, for a g~ven occupancy type. The result is that there tends to be a polarization of residential buildings between inexpensive, low-rise, basically wood-frame struc-

12-2

•

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•

tures on the one hand; and high-rise or mid-rise structures with fire-proof frames made of steel or concrete, with elevators on the other hand. It is impractical and unnecessary to build small, low buildings using massive construction. This of course has strong implications for passive heating.

At this point, each of the codes has a different sequence, although all three of them ultimately cover the same material. The UBC is used here as an example. The next section in the UBC regulates the quality and design of the materials used in construction. It is organized into a general set of requirements, a chapter on masonry, wood, concrete, steel, and aluminum. Next is a section on construction de­tails. It includes an important chapter on stairs, loads, and occupant loads. One area of pertinence to photovoltaics concerns roof construction and coverings. The following section deals with fire-resistive standards for construction and finish materials. Next are regulations for the use of public streets and projections over public property followed by requirements concerning wall and ceiling coverings. These are structural requirements rather than fire requirements. A series of special sub­jects, dealing with prefabricated construction, elevators, light transmitting plastic, glass, etc. is treated. The code ends with a list of ref.erence standards. In the appendix of UBC are a series of additions to various chapters, as well as several new chapters dealing with energy conservation, membrane structures, fail-out structures, and excavation and grading.

In addition to these basic requirements, some of the codes will have special items that are included in that particular code, or which are emphasized because of their regional importance. The UBC is generally used in the West; the SBC in the South; and the BOCA code in the Midwest and East. In addition there is a considerable

... amount of overlapping. There are also some states which have no code at all. The SBC, for instance, has a more detailed section on rat-proof construction, since it deals with tropical climates where rats are a serious problem. Since it deals with most of the major earthquake areas in the country, the UBC has a more detailed sec­tion on earthquake construction.

• Code Sections Pertinent to Residential Photovoltaic Systems

While the entire code relates to residential construction, only a few of the code sections have a direct bearing upon the construction issues raised by residen­tial buildings having photovoltaic systems. This analysis is therefore limited to the code sections dealing with the following issues:

12-3

• Procedures for dealing with alternates, modifications and appeals • Occupancy types and specific requirements for residential occupancies

which might relate to energy or PV issues • Area and height limits for residential occupancy types by construction

types

• Fire-retardant roof construction • Snow, wind, seismic and mechanical loads imposed by PV arrays on the roof • Fire stopping requirements for vertical chases • Attic fire stopping, parapets, roof drainage and other matters related to

roof construction

• Light-transmitting plastics used in roofs • Energy conservation standards • Any matter which might regulate the construction or location of mechanical

equipment rooms, batteries or power conditioning equipment within a build­ing

The Standard Building Code Alternate materials and alternate methods of construction must be equivalent

to that specified in the code. There is no way to deal with totally new elements, only substitutions. The buildtng official makes the decision. (103.6)*

The building official can set added requirements which are not covered by the code. (103.5)

The building official can require tests or test reports as proof of compli­ance with the code. (104)

One can appeal if the building official does not feel alternative methods for 103.6 which are proposed are adequate to meet the code (112 and 113).

In the Fire District (an area defined by individual communities in which high

density construction requires special concern), roofs must be Type A or B as defined in Chapter VI. (301.3)

Residences are all classified as Class R. (401)

*Specific paragraph of the code which covers this item.

12-4

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A one-hour fire rating is required between separate tenants in a multi-family dwelling. (403.2)

Town house party walls need have only a two-hour rating if the building is less than three stories, and needs to extend only to the undersi~e of the roof sheath­ing. The underside of the roof shall have a one-hour rating for four feet on either side of the party wall. In other words, if less than three stories, the party wall of a town house does not have to penetrate through the roof (which would cast a shadow on the PV array). (403.3)

Frame houses are Type VI construction. (607)

Party and fire walls shall be four-hour construction, and shall extend three feet above the roof (except per Paragraph 403.3). Walls within three feet of a property line must be one-hour construction with no openings. Percentage limits on openings depend on the distance from the property line (Table 600) .

One and two family dwellings are exempt from requirements that openings through floors and roofs be enclosed. (701.1a)

This is also the case for vertical shafts. (701.1b)

Floor penetrations by pipe or conduit must be fire stopped with non-combustible materials. (701.1F)

There must be fire-stopping in all walls and partitions, and there must be non-combustible fire-stopping around all pipes, ducts and conduits which penetrate floors. (7051)

Attic and floor spaces must be subdivided into 3000 sq. ft. areas by draft­stops. (705.2)

Roof Coverings: 706.1 through 706.5 define sets of classes for roof cover­ings -- A, B, C. Wood shingles or shakes can be used per paragraph 706.6. The sec­tion does not regulate carports or detached garages. (706)

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If the building is three stories or fewer, and outside the Fire District, and 900 sq. ft. or less, and six feet or more from the property line, wood shingles or shakes can be used. (706.6)

Roof covering must provide weather protection. (706.7)

Foam plastics may be part of roof covering if so tested. Foam nearest the in-

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terior shall be protected per paragraph 717.2(a)2 -- this means using 1/2" gypsum • board. If the roof is not class A, S, or C, foam can be laid over 1/2" plywood with blocked edges. (707. 2d)

A stairway to a roof which is less than a 4:12 pitch is required if the build­ing is four stories or more. A 2' x 3' scuttle is acceptable as a substitute. (1120 )

Minimum roof live loads are set. (Table 1203.7)

Roof must shed water or be designed for the· accumulation of water. (1203.7b)

Include special added load as extras. (PV would be in this category). (1203.7c)

An elaborate procedure for calculating snow loads is included. Each condition is taken separately, with a concern shown about snow falling off one surface onto another, and drifting into notches. (1203.78)

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A procedure is defined for calculating wind loads, including various "shape" factors. (1205) •

Seismic loads refers to ANSI A58.1. (1206)

Access openings are required into attics from below. (1707.7)

Attics must be ventilated. Cross-ventilation is required. The ratio of the net free ventilating area to the area of the ceiling shall not be less than 1/150. The ratio may be reduced to 1/300 if a vapor barrier is installed on the warm side • of the ceiling and if one-half of the required area is high on the roof and the other half consists of eave vents. (1701.8a)

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Any roof covering permitted in the code may be applied to dwellings. If com­position roofing is used, solid sheathing must be used under the roof. (1707.9a)

Flashing shall be placed around openings and extensions of mechanical ap­

pliances or equipment through the roof. (1707.9b)

Attics shall have provision for the emission of excess heat. (200l.lC)

"The provisions of this chapter (Chapter XXVI) shall govern the qual ity and methods of application of plastic for use as light-transmitting materials in build­ings and structures." If a PV array is surface or stand-off mounted above a roof which in all other respects meets the code, it should be considered as a roof cover­ing and not as a light-transmitting plastic material, even though the light does go through the plastic to reach the PV cells. In the case of stand-off and surface mounted arrays, Chapter XXVI would not be applicable, although it might be mis-applied to refer to them. If, however, the PV array is mounted into the roof in place of the normal sheathing and roof covering, it will be much more similar to a roof panel as defined in 2601.2 (d): " ... pl astic materi als which are fastened to structural members or to structural panels or sheathing and whiCh are used as light­transmitting media in the plane of the roof". The limits on the sizes of roof panels are severe. Table 2604 limits the area of a plastic roof panel or skylight to 30% of the area of the floor sheltered by the roof in whi ch the pane 1 or skyl i ght is located. The Table does not apply to one-story buildings not exceeding 1200 sq. ft. in area. The possibility that the requirements of Chapter XXVI might be used to regulated integral mounted PV arrays may be a good reason for not using integral

• mounts. (2601.la)

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This appendix deals with hurricane requirements, and is included since the SBC covers most areas in the country with annual extreme highest wind speed (30 ft.

above the ground, 100 year mean recurrence intervals) which exceed 100 mph. The appendix deals primarily with methods for holding down exterior walls and providing tie beams. The fact that wind speeds up to 130 mph are listed on the wind speed charts for Southern Florida and Cape Hatteras indicates that code officials in the SBe areas might be more alert to the wind-loading requirements for PV arrays. (Ap­pend i x "0").

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This appendix deals with tying down mobile homes, and in a similar way to the hurricane standards, alerts a building official to the necessity for preventing

winds from overturning mobile homes. The addition of a PV array to the top of a mobile home would obviously exacerbate the problem, and might lead a building of­

ficial to set additional standards for mobile home tie-down. (Appendix "H")

This appendix incorporates the ASHRAE 90 standards; in the form of the "Code for Energy Conservation in New Building Construction", adopted by the model code agencies (Appendix IIJII).

Uniform Building Code

Alternates - same as SBCC.(105)

Modifications - bui lding official can change elements for special cases. (106 )

Board of Appeals - same as SBCC (building official member) (204)

Occupancy types: R-1 (apartment)

R-3 (dwelling) (Chapter 12)

R-1 2 stories, 3000 ft2 per floor above 1st, minimum 1 hour construction, except within unit (1202b).

Must be able to maintain 700 F in every room at 3 feet from floor (1210b)

R-3 building can be unlimited in area

R-1 is limited by construction type. Maximum area of one floor: Type V 6000 ft2 Type V 1 hour 10500 ft2 Type III 1 hour 13500 ft2 Type I I F.R. 29900 ft2 Type I unlimited (Table 5-C)

R-3 limited to 3 stories

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• R-l limited by building type: 2 stories, non protected V

3 stories, 1 hour V

4 stories, 1 hour I II

12 stories; F.R. II

over 12; F.R. I (Table 5-D)

Set limits on total area of multi-story bUilding, and on area of upper floors,

4It based on setbacks from and exposure to public ways (505,506).

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Construction types are defined (Chapter 17).

Roof covering must be fire retardant in types I and II. Can use ordinary covering for III, IV and V, for all R-3 and for R-l 2 stories and 3000 ft2 roof (1704).

Parapets required on fire-resistive walls, unless they terminate at 2 hour non-combustible roof. (1709a)

Foam plastics must have flame-spread rating 75, smoke developed rating 450 per UL standard test method, Subject 723 (Dec. '77). (1717a)

Foam plastic can be used in roofs providing there is 15 minute barrier of 1/2" gypsum board or equivalent between roof and interior, per ASTM Standard E119-73 (1717b l.B)

• Foam plastic can be used as roof covering if part of Class A, B, or C roof assembly. No limit to smoke developed rating in roofs. (1717b-4)

Roof covering shall be fire retardant in Type II construction per 3203 (1906)

Snow loading shall be determined by building official (2035d)

Must take account of special roof loads per Table 23-B. (2308a)

• Category 7 is mechanical and electrical equipment (dead load) (Table 23-B)

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Design wind loads per 23F, unless form factors (determined by wind tunnel or other recognized method) indicates differently (2311a)

Defines wind loadings on miscellaneous structures, which would presumably in­

clude supported solar arrays (2311f)

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Section on seismic design (2312) ~

Firestopping required at pipe, duct, etc. holes. Not necessary that it be non-combustible (2517 f-1F)

Draft stop OVer suspended ceilings every 1000 ft2 (2517 f-2)

Roof covering shall be securely fastened to supporting roof construction (3202a)

Roofing materials shall conform to applicable standards in Section 6001, Chapter 21 (3202b)

Definitions; includes:

"Prepared Roofing is any manufactured or p,rocessed roofing material, other than untreated wood shingles and shakes, as distinguished from built-up coverings." (3203b)

Lists detailed requirements for various kinds of shingle and tile roofs (3203d-3)

Lists detailed requirements for "Other Roof Coverings" (metal, asbestos ce­ment, sheet roofing) (3203d-4)

Fire retardant roof covering is defined as a Class A or B built-up roof or prepared roof; Class C mineral surfaces asphalt shingles 235# or more; asbestos

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cement; concrete; metal; slate; clay tile; Class B wood shingles or shakes (3203e) •

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Combustible roof insulation is permitted, if approved roof covering is ap­plied. If fire retardant roof, insulation must be approved type for the deck and

roofing (3204)

Must have access to attics (3205a)

Subdivide attics every 3000 ft2 with draft stops (3205b)

Attics and rafter spaces must be ventilated, if required by building offi­cial, by free area of 1/150th of area of space, except 1/300th if 50% at top and remainder at eaves. In R-l eave vents cannot be put within 3 feet of windows

(3205c)

Roofs must be designed for water, or sloped to drain (3207a)

Requires Type 30 felt under metal shingles and non-interlocking tile and Type 15 felt under asphalt and composition shingles (Table 32-B)

Must have stairway to roof in buildings 4 stories, if roof slope 4/12 (3305c)

Firestop holes, through fire resistive construction per ASTM E119-73 (4304e)

Deals with light transmitting plastic used in roof panels. Panels must be minimum of 4 feet apart. Various classes of plastic limited in size where used over spaces (5206a)

Deals with plastic diffusors supported on metal ceiling suspension systems (5208)

Requires sound insulation between dwelling units and service areas. Remain­der of 3501 details the requirement (3501a)

Requires that buildings be designed per Dec. 1977 joint "Code for Energy Con­servation in New Building Construction." (This is official code verison of ASHRAE 90.) (Chapter 52)

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Basic Building Code 1978 (BOCA) Modification: similar to SBC (109.2)

Alternates: Similar to SBC (109.4)

Board of Appeals: Similar to SBC (126.0)

Definitions -- Roof Covering: The covering applied to the roof for weather resistance, fire-resistance, or appearance (201.0)

Use Group R, residential buildings (209.0)

R-1: hotels, motels, dormitories, etc.

R-2: multi-family and small dormitories

R-3: one or two-family with boarders

R-4: detached one or two-family (subject either to regulations for R-3, or to special One- and Two-Family Dwelling Code). (209.2)

Require handicapped access for use groups R-1 and R-2 (315.0)

This article covers "high hazard" uses, which includes uses " ... involving the storage, manufacture, handling or filling of flammable and volatile solids, liquids, or gasses which generate combustible and explosive air-vapor mixtures," along with places of assembly, garages, etc. A battery room should not be classed as a highhazard use. (400.0)

High hazard uses (unless otherwise specifically approved in the code) shall not be located within the local fire zone, or in wood frame construction, or within 200 feet of a public building, nursing home, etc. (400.9)

Explosion hazards shall be provided with explosion relief systems. 401.2, 401.3, and 401.4 detail the requirements for such vents, which are prohibitively restrictive for residences (20 feet from windows and property lines, etc.). (401.1)

Periodic housekeeping inspections are required for high hazard uses. (403.2)

Ventilation at two air changes per hour can be used instead of operable sash in a habitable room. (504.3)

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Glass area in a habitable room must be at least 8% of the floor area, with at least one-half openable. (506,2)

Attic spaces must be ventilated with at least one-third of 1% clear vent

area. (507.2)

Regulates sound transmission between units in multi-family dwellings. (522.0)

Every sleeping room below the fourth floor must have an escape window or door to the outside. Sill must be less than 44" high. Must provide clear opening of 5.7 sq. ft. (5.0 sq. ft. at grade). Must be at least 24" high and 20" wide. (This prohibits certain passive designs which use only south facing clerestories for bed­rooms). (609.4)

Defines roof live loads (Table 710)

Roofs used for special purposes shall be designed for actual loads (710.5.2)

Refers to App. l-102.0, which shows snow load isobars for 25, 50 and 100 year mean recurrence. (In Boston, the value~ are 25, 30 and 40 psf respectively) (711.1)

R-1 uses must use 100 year recurrence load; R-2 and R-3, 50 year load (711.2)

Refers to App. l-102.2a-c, which shows a s~ries of roof geometries and de­fines appropriate design coefficients for snow accumulation loads (711.3.1)

Defines wind loads in some detail, using a 50-year mean recurrence interval chart, and a table of ordinary velocity pressures (712.0)

Secondary structural members must withstand 1.5 times primary loads (713.4.1)

Defines wind loads on signs, etc., as equal to laods on secondary members (715.0)

Refers to App. l-101.0, which is a brief earthquake design section (716.1)

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Exempts one- and two-family dwellings from earthquake requirements (716.2)

Lists combinations of loads and their probabilities (717.0)

Defines tests for materials, to meet code. Basically deals with masonry and plywood used for walls (800.0)

Concealed roof spaces, if not non-combustible, fire-proof, or equipped with sprinklers, must be fire-stopped every 3000 sq. ft. (B75.6)

Firestopping required in stud walls and partitions, above ceilings at top floor, etc. (875.9)

Foam plastics can be used in walls and ceilings if adequately protected, and if smoke-developed rating is less than 450 per ASTM E-84. (876.5)

Sets fire grading classification for each use group. R-2 = 1.5 hours; R-3 = 1 hour (Table 902)

Roof coverings classify per ASTM E 108-75 (903.3)

Class A - effective against severe fire exposure, and includes cement, con­crete, slate, masonry, tile, etc. (903.3.2)

Class B - moderate (903.3.3)

Class C - light (903.3.4)

Special fire resistive requirements (905.0)

Special fire resistive requirements for residential buildings. These are technical issues relating allowable height and area to construction type (905.6)

Cannot use uninhabited spaces or cavities (attics, cellars, cavity walls, etc.) as replacement in plenums. Line joist spaces can be used in one- and two­family dwellings only for use as replacement air plenums (905.10)

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RESIDENTIAL LOAD CENTER REPORT DISTRIBUTION

DISTRIBUTION:

Department of Energy (4) Division of Photovoltaic

Energy Systems Forrestal Bldg. 1000 Independence Ave. SW Washington, DC 20585 Attn: L. A. Barrett

M. B; Prince V. N. Rice S. J. Taylor

Department of Energy Division of Active Heating

and Cooling Office of Solar Applications

for Bldgs. Washington, DC 20585 Attn: Robert D. Jordon, Director

Department of Energy Div~sion of Passive and Hybrid Off~ce of Solar Applications Washington, DC 20585 Attn: Nichael D. Maybaum

Director

Jet Propulsion Laboratory (8) 4800 Oak Grove Drive Pasadena, CA 91103 Attn: R. G. Forney

R. V. Powell (3) R. Ferber R. Ross R. S. Sugimura R. Weaver

Jet Propulsion Laboratory Solar Data Center MS 502-414 4800 Oak Grove Drive Pasadena, CA 91103

R. Tabors (2) MIT-Energy Laboratory E40.l72 Cambridge, MA 02139

Dist-l

Solar Energy Research Institute (5) 1617 Cole Boulevard Golden, CO 80401 Attn: D. Feucht

C. Bishop R. Koontz G. Sussman L. Mrig

SERI, Library (2) 1617 Cole Boulevard, Bldg. #4 Golden, CO 80401

NASA Lewis Research Center 21000 Brookpark Laboratory Cleveland, OR 44135

EPRI (3) P.O. Box 10412 Palo Alto, CA 94303 Attn: Frank Goodman

Edgar Demeo Roger Taylor

Aerospace Corporation (2) P;O. Box 902957 Los Angeles, CA 90009 Attn: S. Leonard

B. Siegel

NIT-Lincoln Laboratory (3) P.O. Box 73 Lexington, MA 02173 Attn: M. Pope

M. Russell E. Kern

Office of Technology Assessment U. S. Congress Washington, DC 20510

New Mexico Solar Energy Inst. (2) New Mexico State University Box 3S0L Las Cruces, NM 88003 Attn: John Schaeffer

General Electric Co. Advanced Energy Programs P.O. Box 8661 Philadelphia, PA 19101 Attn: E. M. Mahalick

Distribution cont'd

Mass Design 138 Mt. Auburn St. Cambridge, MA 02138 • Attn: Gordon Tully

Sandia National Laboratories 3141 L. J. Erickson (5) 4700 J. H. Scott 4720 D. G. Schueler 4721 w. P. Schimmel 4723 D. Chu 4723 J. L. Jackson 4723 G. J. Jones 4723 T. S. Key 4723 H. N. Post • 4724 L. C. Beavis 4724 E. C. Boes 4724 M. Rios 4724 N. w. Edenburn 4726 H. H. Baxter, Jr. 4726 K. L. Biringer 4726 E. L. Burgess 4726 C. B. Rogers (20 )

3151 w. L. Garner (3)

3154-3 C. H. Dalin (25) For DOE/TIC (Unlimited Distribution) •

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Dist-2