Steven Carlson, P.E.CDH Energy Corp.Evansville, WIwww.cdhenergy.com

WGBA Leadership ConferenceOctober 19, 2005

Effective Energy Modeling

Presentation Overview

WhatWhyHowIllustrated by experiences in the AlbericiWorld Headquarters LEED Platinum project

Experience –Building Performance

Energy Simulation Development• Buildings – Loads, part-load performance, etc

• Technologies (GSHP, Desiccants, Refrigeration, etc)

Energy Technology Demonstration• Field data

Building Performance• Metrics• Commissioning• Monitoring & Verification

Energy Project Development• Feasibility Studies• Energy Management

Whole Building Energy Analysis

Hourly simulationComprehensive Integration• Loads• Systems• Plant• Economics

Requires detailed design input to represent:• Shell• Systems• Equipment• Use

State-of-the-Art Software ReviewARTI 2001

Whole Building Energy Analysis• Only used regularly by 5% of respondents• When client requires it• Not well linked with tools already used

Green Design Tools• Previous experience (31%)• Mfg. literature (20%)• Rating system (13%)

Energy Analysis & Code Compliance Tools• Paper forms (27%)• Mfg. software (18%)• Previous experience (10%)

Tools Used “Most Often”HVAC Equipment Sizing:

What Method Do You Use Most Often?

.8%

4.2%

6.8%

8.5%

11.0%16.9%

51.7%Other

Manual J w orksheet

Bldg energy sim

3rd party sizing sof

OtherPrevious experience,

Mfgs' sizing softw ar

ARTI Focus Group Findings

HVAC loads software is common• Design tradeoffs are evaluated in some cases

– Mostly glazing; lighting generally not considered– Depends on when the ME is brought into the process

• Schedules don’t permit much interaction between disciplines– Design-build projects more likely to encourage collaboration

• Iterations, especially cost estimating, are time consumingLots of software being used• CAD • Equipment selection / System sizing• Cost estimating

Lots of redundant data entry – looking for data exchange

Why Use WBEA ?

Where simple load and sizing analysis is not enough:Daylighting benefits/tradeoffsLighting / HVAC / Shell tradeoffsHVAC control issues (economizer, DCV)Geothermal Heat Pumps vs. other systemsDehumidification performanceNatural /Mixed VentilationThermal storage

Whole Building Design

Treat building as a systemInteractions of design decisions (first cost & operating cost)• architectural form, • opaque shell,• glazing,• lighting,• HVAC systems

Example of benefits:• Better windows vs. less HVAC• Reduced lighting power density vs. less HVAC

Requires Team Communications

Energy Modeling - Why?

To inform design• Options analysis

To obtain LEED points• Number one driver of energy modeling / Whole

Building design process• “….energy savings? Who cares, just give me

my points!”To set performance targets• Review building data (M&V)• Baseline for energy management• Alberici M&V plan with 5 min DDC data archive

To Inform Design

Options Analysis• To quantify options before design is finished• Requires tradeoff between design details and

assumptions• Requires communication of intent

– Budget– Schedule– System performance requirements

• Requires model detail appropriate for analysis• Need to build confidence in model results

– Parametrics• Modeling is most appropriate for relative

comparisons

Alberici World HeadquartersDesign Features

Shell insulation• R-19 metal frame• R-30 roof• Glazing: U=0.31, SHGC = 0.20 & 0.23

Lighting• 0.64 W/sq ft building• 0.20 W/sq ft parking garage• Daylighting control (35 f.c.)

HVAC System• UFAD at 2.3 in wc static pressure• Perimeter powered boxes for heat• Variable speed supply fans• Energy recovery ventilation with economizer mode• Active humidity control• Natural ventilation

Alberici World HeadquartersDesign Features

Equipment - Cooling• HCFC free screw chillers• Variable speed tower• Water-side economizer• Variable speed secondary loop pumping

Equipment - Heating• Full modulating condensing boilers• Interconnection to CHW coils for morning

warm-up• Domestic hot water solar preheat (380 sq ft)

Renewable Electricity Production• 65 kW Wind Turbine

To Obtain LEED PointsEnergy

Regulated Energy Energy Peak Energy Peak ImpactSummary by End Use Energy Type [kWh] [kW] [kWh] [kW] [%]Interior Lighting Electricity 162,251 60 472,016 150 66%Exterior Lighting Electricity 72,528 27 101,380 38 28%Space Cooling Electricity 106,393 143 160,605 119 34%Vent Fans Electricity 41,042 16 70,301 12 42%Pumps & ERV Fans Electricity 34,448 20 64,322 39 46%

Energy Peak Energy Peak Impact[therm] [Btu/hr] [therm] [Btu/hr] [%]

Space Heating Natural Gas 9,915 2,430,899 20,415 5,436,068 51%Service Water Heating Natural Gas 450 34,801 1,181 34,801 62%

Energy & CostSource Energy Cost

Source Energy Cost Energy Cost

Summary by Fuel [106 Btu] [$] [106 Btu] [$] [%] [%]Electricity 4,267 32,517 8,895 67,538 52% 52%Natural Gas 1,037 9,971 2,160 19,408 52% 49%Subtotal Non-Renew (DEC') 5,303 42,488 11,054 86,946 52% 51.1%Sutotal Renewable (REC') (951) (7,596) - - Total 4,352 34,892 11,054 86,946

Percentage Savings = 100 x (ECB'$-DEC"$)/ECB'$= 59.9%

Credit 1 Points = 10

Designed Building Budget Building

Designed Building Budget Building Impact

Alberici World HeadquartersEnergy Model Representation

Daylighting analysis increased emphasis on geometry.HVAC zoning to match design

Energy Management• Whole Building• Systems & Equipment Performance

Model calibration vs system performance• Schedules• Operating parameters• Performance curves

M&V plan closes loop to verify performanceRequires building operational data and analysis• Alberici M&V plan with 5 min DDC data archive

To Set Performance Targets

Performance Targets - Patterns

Total Building Power Operating Pattern - Energy Model

Day (MAX/MIN = 450.20/ 80.70 kW)

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Total Building Power Operating Pattern

Day (MAX/MIN = 445.13/ 0.00 kW)

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Performance Targets - Patterns

Lighting Power Operating Pattern - Energy Model

Day (MAX/MIN = 73.60/ 7.40 kW)

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Lighting Power Operating Pattern

Day (MAX/MIN = 83.00/ 0.00 kW)

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Performance Targets - Trends

Daily Total Electricity Use

0 20 40 60 80 100Daily Average Outdoor Dry Bulb Temperature (F)

0

1000

2000

3000

4000

5000

6000

7000

8000

kWh/

day

WeekdaySundaySaturday

WeekdaySundaySaturdaySimulation

Model adjusted with extended operating hours

Performance Targets - Trends

System by system performance trend reviews• Proving fan modulation with plant heating and cooling loads

Fan Energy Heating/Cooling Load Relationship

-20 -10 0 10 20 30Daily Net Heating(-) Cooling (+) Load (MMBTU)

0

200

400

600

800

AH

U F

an E

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ricity

(kW

h/da

y)

Performance Targets - Trends

HRU #2 Return Air CO2 Concentration

February March April May June July August2005

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(ppm

)

HRU Unit #2 Return Air CO2

Day (MAX/MIN = 795.50/ 368.75 ppm)

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operation reduces CO2 levels

Summary – Effective Modeling

Adds value by integrating energy simulation into design process• Options analysis• Model informs the design

Goes beyond modeling for points• Modeling alone does not improve efficiency

Provides a tool for energy management• Baseline / Performance Targets

– Whole building– System– Equipment– Sequence of Operations

• Close the loop – data informs the model• Build confidence in the process – ready for next project