Measure Information Template â€“ Office Task Lighting Controls

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CONTENTS

1. Overview ....................................................................................................................... 4

2. Methodology................................................................................................................. 5

2.1 Task Lighting and Plug Load Controls.......................................................................................6

2.2 Literature Review .......................................................................................................................6

2.3 Market Survey ............................................................................................................................7

2.3.1 Survey Audience and Objectives .........................................................................................7

2.3.2 Survey Methodology ............................................................................................................8

2.4 Energy Savings Analysis ............................................................................................................8

2.5 Cost Analysis ............................................................................................................................10

3. Analysis and Results ................................................................................................. 14

3.1 Task Light and Office Plug Load Characteristics ....................................................................14

3.1.1 Energy Consumption .........................................................................................................14

3.1.2 Definition ...........................................................................................................................15

3.1.3 Characteristics ....................................................................................................................16

3.2 Market Survey ..........................................................................................................................18

3.2.1 Plug Load Control Standards .............................................................................................18

3.2.2 Industry Survey ..................................................................................................................19

3.3 Task Light and Plug Load Control Strategies ..........................................................................20

3.3.1 Dual Circuit ........................................................................................................................21

3.3.2 Available Products .............................................................................................................22

3.3.3 Central Timer Control Design ...........................................................................................24

3.3.4 Occupancy Sensor Control Designs ...................................................................................27

3.4 Energy Analysis ........................................................................................................................30

3.4.1 Task Lighting and Plug Load Operation and Control Parameters .....................................30

2013 California Building Energy Efficiency Standards – Office Task Lighting [February 2011]

3.4.2 Office Building Prototypes ................................................................................................37

3.4.3 Energy Savings Analysis Results.......................................................................................39

3.5 Cost Analysis ............................................................................................................................40

3.5.1 Level 1 Control Cost ..........................................................................................................42

3.5.2 Level 2 Control Cost The last strategy implements task lights and plug load control by controlling central circuits serving open spaces and copy rooms, and controlling locally private spaces and conference rooms. .........................................................................................................45

3.5.3 Level 3 Control Cost ..........................................................................................................48

3.6 Cost Effectiveness Analysis .....................................................................................................49

4. Bibliography and Other Research ............................................................................ 50

FIGURES

Figure 1 Energy Savings Calculation Formula Schedule ..................................................................... 10

Figure 2. Mixed Load Breaker Panel and Lighting Control Panel Base Case ...................................... 11

Figure 3. Single Voltage Load Breaker Panels and Lighting Control Panel Base Case ....................... 11

Figure 4. Overhead Lighting Controllable Breaker Panel and Single Voltage Breaker Panel Base Case ........................................................................................................................................................ 12

Figure 5. Number of circuits per space type ......................................................................................... 13

Figure 6 Office Task Lights Operation during Weekday and Weekend .............................................. 15

Figure 7. Example of Essential Equipment ........................................................................................... 17

Figure 8. One Circuit Practice .............................................................................................................. 21

Figure 9. Dual Circuit Practice ............................................................................................................. 21

Figure 10. Central Control Products ..................................................................................................... 23

Figure 11 Occupancy Sensor Products ................................................................................................. 24

Figure 12 Baseline A Improvement: Increase control relay panel capacity ......................................... 25

Figure 13 Baseline B Improvement: Replace breakers by controllable breakers in the plug load breaker panel [option 1] ................................................................................................................. 25

Figure 14 Baseline B: Increase control relay panel capacity [option 2] ............................................... 26

Figure 15 Baseline C: Increase controllable breaker panel capacity [option 1] ................................... 26

Figure 16 Baseline C: Replace breakers by controllable breakers in the plug load breaker panel [option 2] ........................................................................................................................................ 27

Figure 17 Baseline D: Replace regular breakers by controllable breakers ........................................... 27


Figure 18. Occupancy sensor switch for overhead lighting and occupancy sensor switch for plug loads ........................................................................................................................................................ 28

Figure 19. Occupancy Sensor Linked to a Relay Box .......................................................................... 29

Figure 20 Controllable Plug Load for Timer and Occupancy Sensor Controls .................................... 31

Figure 21 Plug Load Density and Power States.................................................................................... 32

Figure 22 Office Operation and Occupant Working Schedule Assumptions ....................................... 33

Figure 23 Plug Load Operation Status – Non-Business Hours ............................................................. 34

Figure 24 Plug Load Operation Status – Away-from-desk .................................................................. 35

Figure 25 Plug Load Operation Status – Empty Conference Room ..................................................... 36

Figure 26 Small office activity breakdown ........................................................................................... 37

Figure 27 Large office activity breakdown ........................................................................................... 38

Figure 28 Large Office Floor Plan ........................................................................................................ 38

Figure 29 Annual Unit Energy Savings (kWh/sf)................................................................................. 39

Figure 30 Annual TDV Energy Savings (kBtu/yr) ............................................................................... 39

Figure 31 Lifecycle Benefits ................................................................................................................. 40

Figure 32. Central Control Strategy – Incremental Equipment Requirement ...................................... 43

Figure 33. Central Control Strategy – Additional Wire Requirement .................................................. 43

Figure 34 Central Control Strategy - Incremental Equipment Cost ...... Error! Bookmark not defined.

Figure 35 Increment Costs - Level 1 Control ....................................................................................... 44

Figure 36 Central Control & Occupancy Sensor Strategy - Equipment requirement ........................... 46

Figure 37 Central Control & Occupancy Sensor Strategy - Equipment requirement ........................... 46

Figure 38. Incremental Cost – Level 2 Control .................................................................................... 47

Figure 39. Occupancy Sensor Strategy - Equipment Requirement ...................................................... 48

Figure 40 Occupancy Sensor Strategy - Incremental Equipment Cost ................................................. 48

Figure 41 Incremental Cost – level 3 .................................................................................................... 49


1. Overview

On behalf of Southern California Edison (SCE) as part of the statewide IOU Codes and Standards Programs, Heschong Mahone Group (HMG) is conducting a Codes and Standards Enhancement (CASE) study on office task lighting controls.

According to the California Commercial End-Use Survey1 (CEUS) released in March 2006, interior lighting represents 26.4% of the electricity energy consumption in California office floor space, corresponding to the highest electricity end-use. This interior lighting can be divided into overhead lighting and task lighting. Per the 2008 Title 24 code requirement, the allowed lighting power density in office spaces is 1.1 W/sf which can be broken down as follows: 0.9W/sf for overhead lighting and 0.2W/sf for task lighting. Hence, about 18% of the interior lighting electricity consumption is due to task lighting.

In addition, office equipment has the third highest electricity end-use consumption in California office floor space, representing 19.2% of the total electricity consumption. When considering the energy consumption of miscellaneous equipment and task lighting, office plug loads become the highest electricity end-use of office buildings (28 % of total electricity consumption). Despite penetration of newer and more efficient technologies, this electricity end-use is steadily increasing as the use of personal computers and other electronics devices in offices continues to grow. New Title 24 code proposals that push toward low ambient (overhead) lighting are promoting increased task lighting usage. These two trends are increasing the importance of controlling plug loads in offices.

The CASE study aims to develop Title 24 requirements to reduce office task lighting and plug load energy consumption through automatic shut off controls.

1 California Commercial End-Use Survey.Energy Commission. CEC-400-2006-005


2. Methodology With increased practices of low ambient lighting designs and use of overhead lighting controls in office spaces, task lighting becomes a more prominent office building lighting load in terms of both power density and power consumption. The 2008 Title 24 assumes that task lighting power density can be 0.2 W/sf, which is 18% of the total allowed office lighting power density of 1.1 W/sf.

In a broad view, electricity consumption by office plug loads, which include task lighting load, has been increasing steadily as the use of personal computers and other electronics devices in offices continues to grow. Forecasts by the Energy Information Administration’s 2010 annual energy outlook predict a 36% increase in PC office equipment energy consumption from 2010 to 2030, and a 65% increase for non-PC office equipment energy consumption. Combined, these two end-uses would increase the total office energy consumption by 51%. Although the growth in office equipment use is difficult to control, office equipment use patterns give room for energy savings. The CASE study investigates strategies of applying existing lighting control technologies, especially those already required by 2008 Title 24 for general lightings, to task lightings and plug loads.

Key elements to our study methodology are listed here:

Literature review Industry surveys for installation practices and product information

• Survey of ASHRAE 90.1-2007 Addendum bs. Development • Survey of IgCC code development team • Interview lighting control manufacturers

Energy Savings Analysis The CASE team started the investigation by reviewing literature on these control strategies, on related case studies and on products available to implement these strategies. Then they interviewed product manufacturers, and experts involved in the plug load management fields, such as researchers from NBI and ECOS and ASHRAE committee members who worked on 90.1-2007 Addendum bs.

From this research, different implementation options were defined depending on control product type and common practice, and different possible configurations. The CASE team accounted for control installation system which will be in place in office buildings due to current Title 24 lighting control requirements, and considered incremental changes as well as new installations. They collected further product technical information and product costs by interviewing sales representatives and distributors. They also conducted survey of electrical designers and contractors, as well as system furniture manufacturers in order to characterize installation requirement other than control product, such as new wiring configuration, and in order to determine any implementation issue. In particular, we investigated the prevalence of dual circuit layout in office spaces, and any potential issues or barriers to its implementation. These industry surveys are further described in the next section.

Two office prototypes, described in sectionError! Reference source not found., were developed. For each of those, new equipment requirement was defined depending on the baseline, as well as new wiring requirement. When further considering installation, this led to the assessment of the total incremental cost of each option for each prototype, which enabled the cost-effectiveness analysis in combination with the energy savings estimates.


2.1 Task Lighting and Plug Load Controls

The CASE study team investigated a wide range of plug load control technologies and practices in order to develop Title 24 requirement that maximize task lighting/plug load controls. While many of these technologies are effective control strategies, not all of them are suitable for Title 24 regulations.

Task lighting and plug load can be automatically switched off by an embedded occupancy sensor or by the connected power stripe, which has occupancy sensor or timer control capabilities. These appliance level controls are not suitable for Title 24 regulation considerations.

Lighting control technologies for general lighting shut-off controls can be used for task lighting and plug load controls. Plug load controls require separate electrical circuits, dual circuits, to be installed in office buildings. One is kept uncontrolled (primary circuit) to enable essential and emergency equipment to stay on around the clock while the other (secondary circuit) can be shut off when the connected plug loads, including task lights, are not in use.

Based on existing control technologies, this study considers three levels of control, their implementation feasibility and cost effectiveness. The goal is to achieve maximum granularity of controls with the consideration of availability and costs of control technologies. The three levels of controls are:

Level 1: Dual circuits are provided to all building areas. Secondary circuit are controlled by lighting control panels or controllable breaker panels with timer control capability so that connected task lighting and plug load are automatically shut off during non-business hours.

Level 2: Secondary circuits in all cubicles, private offices, and conference rooms are controlled by occupancy sensors.

Level 3: Secondary circuits in private offices and conference rooms are controlled by occupancy sensors. This is consistent with the 2008 Title 24 requirement of occupancy sensor controls of general lighting in those spaces. Secondary circuits in other building spaces follow the strategy 1.

These three strategies can implemented using lighting control systems widely used for meeting existing Title 24 lighting control requirements.

2.2 Literature Review

The team conducted literature review as the first step to investigating the subject of plug load management. Information pertinent to understanding the current status and technology development associated with plug load we wished to obtain from literature review included:

Task light and plug load characteristics Energy consumption impact from task light and plug load Task light and plug load control strategies

The team identified two main sources of established studies on plug loads. One is a series of studies conducted by Lawrence Berkley National Laboratory (LBNL). The most recent publication in the series is the report titled, “After-hours Power Status of Office Equipment and Energy Use of Miscellaneous Plug-Load Equipment.” This report built on a previous study, “Field Surveys of Office Equipment Operation Patterns,” and presented data on the type, amount and typical annual energy


consumption of miscellaneous plug load equipment usually not accounted for by building managers. The second source of literature is the Office Plug Load Field Monitoring2 ” PIER research conducted by ECOS and RLW Analytics which monitored plug load consumption in commercial offices in 2007 and 2008 inventoried all plug load devices at 47 offices.

2.3 Market Survey

Surveys were conducted amongst the different industry players, using diverse methodologies. The purposes of these surveys were to gather information on

Plug load control recommendation in other codes Wiring industry practice Feasibility of different task light and plug load control options. Product and pricing information

2.3.1 Survey Audience and Objectives

The CASE team interviewed the ASHRAE 90.1 technical committee members who developed the ASHRAE 90.1 Addendum bs on plug load control to understand their code development process and stakeholder reactions on the proposal. The team also interviewed New Building Institute (NBI) staff who helped to develop the plug load control recommendation for both IgCC code and for the the Office of the future 25% solution.

Electrical designers and contractors were interviewed through an on-line survey, while system furniture manufacturers were interviewed through phone calls. Control product technical supports and location distributors were also called for product and pricing information.

The designer and contractor survey was aimed at assessing current wiring practices in private offices and workstation These included the number of independent circuits brought to these spaces. It also sought to determine the feasibility of controlling task lights and plug loads by using a central timer control or local occupancy sensors by asking for potential issues and comments on these strategies. It asked about the frequency of timer and occupancy control strategies implementation in California office spaces.

The system furniture manufacturer survey tried to assess the current practice regarding cubicle workstation wiring, such as the number of independent circuits brought to each workstation and the integration of task light to the workstation partition (under cabinet task light type), in order to evaluate the feasibility of bringing both controlled and uncontrolled circuits to each workstation. It meant to determine the current practice concerning occupancy sensor integration to the system furniture. It addressed the feasibility of integrating occupancy sensor to their system furniture if they hadn’t done it before. It finally asked about the possibility of receptacle colour coding depending on their wiring.

2 2008. Office Plug Load Field Monitoring Report California Energy Commission, PIER Energy-

Related Environmental Research Program. CEC-500-06-007.


After a preliminary research on the internet regarding available and suitable timer control and occupancy sensor products, the technical support of the manufacturers providing these products were called in order to get information not available on specification sheets. Concerning timer control, information on panel type, size (number of circuit), load mixing capability (120V/227V), networking option, override capability and external communication options was collected. Information on controlled area, power pack requirement, sensor technology and wiring voltage was collected on occupancy sensors.

Finally, local distributors were called to get prices of the control systems that would be installed in each building prototypes (small and large offices).

2.3.2 Survey Methodology

Electrical designers and contractors surveys were conducted on-line. Contact information was collected from HMG multifamily building energy efficiency implementation programs, stakeholder meeting attendees and internet resources. A survey form was created using Survey Monkey. A link was then sent to participants in an email using MyEmma. This email explained CASE work general purpose and specificity of this task lighting CASE while inviting them to take part in stakeholder meetings. A reminder was sent a month later to increase the number of response. The survey results were then analyzed using Survey Monkey.

Due to the unavailability of direct contact for system furniture manufacturers, they were called using the technical support number displayed on their website, and HMG staff would fill surveys on Survey Monkey while they talked to their sales engineers. These surveys were then analysed using Survey Monkey analysis capability.

The control product manufacturer survey started with an Internet research on products suitable for task light and plug load control applications in general, and for the two office prototypes more specifically. Specification sheets were collected. Then, the technical support and sales engineers of companies manufacturing these products were called either to confirm information gathered on-line or to collect missing information. Some meetings with sales representatives were also organized for product demonstration, functioning explanation and price collection purpose. Once system components and related model number needed for each prototype were determined, local distributors were called to get price quotes.

2.4 Energy Savings Analysis

The task light and plug load controls aim at managing the energy consumption of these devices by switching off their power supply circuits when employees are not using them. Central timer control reduces plug load power consumption in periods when all employees have left the controlled spaces. In the case of occupancy sensor control, additional savings can be achieved when an occupant is not at his/her desk during business hours, which include two scenarios, away-from-desk times and out-of-office times. Similarly, occupancy sensor control in conference rooms can achieve additional savings when they are not in use.

Basically, there are three scenarios when task lighting and other plug loads can be switched off:

1. During non-business hours 2. An occupant is temporally away from the desk during business hours, or an conference room

is not being used


3. An occupant is not in office during business hours Central timer control can only address the first scenario while occupancy sensor can address all three scenarios. Detailed schedules for all three scenarios are developed.

The amount of energy savings depends on total number of plug load devices connected to the controlled circuit and the average powers of the controlled plug loads when they are switched off. The former depends on office building configurations. The CASE study used two prototype buildings for analysis. The latter were obtained from the LBNL study and ECOS PIER research results.

Based on the above three task lighting and plug load control scenarios, the CASE study evaluated energy savings for each control technology, central timer control and occupancy sensor control in private offices/cubicles and conference rooms. The three levels of building plug load control, as discussed in section 3.2, use different combinations of control technologies. Total building energy savings for each level of control are the summation of savings from all deployed control technologies.

The detailed calculation formulas are as following:

The average load (kW) of a plug load i is:

, ,

i = {controllable plug load for a control technology}

j = {Non-Business hours; Away-from-Desk; Out-Of-Office; Empty Conference room},

PS = {Active, idle, sleep, standby}

At each hour k, the total energy savings (kWh) are calculated as:

, , _ _ _ , ,

Both SCHj,k and Number_of_Connected_Loadi,j depends on control technology according to Figure 1.

The annual energy savings by a technology is:

,


Control Technology

Control Level

j Number_of_Connected_Loadi,j SCHj,k

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Empty Conference

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Average number of conference room plug load

equipment

Fraction of unoccupied time during

business hours

Figure 1 Energy Savings Calculation Formula Schedule

2.5 Cost Analysis

Incremental cost of the proposed measure is determined by lighting control equipment upgrade and associated costs for additional wiring, installation, configuration, as well as maintenance. The CASE team first assessed the lighting control and electrical wiring base cases that are in compliance with the 2008 Title 24 codes, which include automatic shut off controls and occupancy sensor controls for general; lighting. For each base case, system upgrade options were developed. The corresponding costs were estimated based on lighting control products available from the market and prototype office building configurations.

Two base cases were defined depending on the studied control strategy, representing common practice. The base case for central control assumes that the buildings have central panel controlling overhead lighting. Depending on the equipment used, three different base configurations were defined. In the first configuration depicted in Figure 2, a single breaker panel handles both 120V and 277V (if applicable) loads, and a lighting control panel is used to control overhead lighting (120V, 277V or both depending on the building type).

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Private Offices 1 circuit/private office 1/2 circuit/private office

Open Space ½ circuit/cubicle ¼ circuit/cubicle

Copy Room 1 circuit/copy room

Lobby, Corridors 1 circuit

Kitchens 2 circuits/kitchen

Mechanical Room 2 circuits/mechanical room

Lighting Loads Overhead lighting 1.1 W/sf LPD, 3 amp/circuit

1.1 W/sf LPD, 4 amp/circuit

Figure 5. Number of circuits per space type


3. Analysis and Results This section presents the findings of our data collection efforts and the results of energy analysis.

3.1 Task Light and Office Plug Load Characteristics

The information gathered during the literature review and feedback from industry survey regarding load definition and characteristics are captured in the section below.

3.1.1 Energy Consumption

The team’s literature review efforts also yielded findings on office plug load energy consumption impact. One of LBNL’s studies collected data on the after-hour power state and the technology type of office equipment such as computers, monitors, copiers, scanners, printers, faxes and multi-function devices for the Energy Star Office Equipment program. Their scope included performing the calculation of office and miscellaneous equipment density (per employee and per 1000 sf). Following the convention of LBNL’s studies, office plug loads can be broken down into two categories: office equipment and miscellaneous equipment. Office equipment category further consists of task lighting, computer and monitor and office electronics.

The PIER research by ECOS and RLW Analytics metered a subset of 25 plug load devices and recorded power, current, voltage, and power factor with real-time time stamps over a two week period at one-minute intervals. In total, the team inventoried nearly 7,000 plug load devices and collected meter data from 470 plug load devices.

These above-mentioned studies provide the most comprehensive, updated and valuable data on office plug load energy consumption, status, usage and density in commercial offices. Even though numerous studies have been conducted in the last years regarding energy consumption of office equipment and home electronics, they are relatively old (from 1998 to 2002) and usually not specific to office buildings. In particular, after-hours equipment power status and equipment density are particularly scarce information. Most of the information presented in the following sections and most of the following analysis are based on these two studies. Some key results from these studies are presented in the following paragraphs.

Task lighting, in the form of table lamps and under-cabinet attachments are the third biggest load per 1000 sf after desktop computers and monitors when excluding portable space heater. Imaging equipment energy impact is also substantial. Unusual loads such as space heater can have a significant impact on plug consumption due to their high power rating, even though their density is low.

Plug load energy is wasted due to two mechanisms. First, some equipment is left on by occupants when they are away from their desk, be it for a short break or for an extended period of time such as weekend. Based on a research on task lighting usage conducted by HMG in 2009 (Error! Reference source not found.) and task lighting energy consumption data from the ECOS PIER research on plug loads, task lights which are left on during non-business hours can waste about 8 kWh per year per employee.


Figure 6 Office Task Lights Operation during Weekday and Weekend

Second, some office appliances continuously draw power, even when they aren’t performing their primary function or when they are switched off. This electricity usage is called standby power, and is consumed by power supplies, the circuits or sensors needed to receive a remote signal, soft keypads or displays including miscellaneous LED status lights. Standby power density can be substantial for monitors.

3.1.2 Definition

Office equipment definitions tend to deviate from one study to another. We aim to define devices considered as task light and office plug loads for this study.

Title 24 defines task light as the lighting that is designed specifically to illuminate a task location, and that is generally confined to the task location. Currently, task lighting is not regulated by Title 24. The 2008 Title 24 code only specifies that for task lighting with density above 0.2W/sf, the additional W/sf of task lighting installed should be counted into the space light power density. Task lighting devices are commonly used, and their density usually varies between 1 and 2 task lamps per office workstation. Low ambient lighting strategies, which reduce the overhead lighting power density, focus light to workstations and harvest daylight, tend to increase task light densities.

Plug loads are not defined in Title 24. This label can cover different office appliances depending on the studies. For the purpose of this CASE study, data and taxonomy from the two literature sources, LBNL and ECOS PIER project, were used:

Office equipment refers to electronics products found in any type of offices and are primarily designed for office work. It can be further described as task lighting, computer and monitor and office electronics. It designates the following devices, consistently with Energy Star definition:

Task lighting: under-cabinet lamp, table lamp Computer&Monitor

o Computers: desktop, laptop (notebook or mobile), thin clients; o Monitors: cathode ray tube (CRT), and liquid crystal display (LCD);

Office electronics

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o Imaging: -Printers: impact, inkjet, laser, thermal, solid ink, and wide format;

-Fax machines: inkjet, laser, and thermal;

-Copiers;

-Scanners: document, flatbed, slide, and wide format;

-Multi-function devices: inkjet and laser;

o Computer Peripheral: -Computer speakers

-External power adapters; and

-Docking station (laptop, PDA)

Miscellaneous equipment refers to plug-load that are typically portable, often occupant-provided units whose number, power consumption and usage patterns are largely unknown [After-hours Power Status of Office Equipment and Inventory of Miscellaneous Plug-Load Equipment, LBNL].

There is not a comprehensive list of any plug load that can be found in offices. Due to the extensive number and variety of office plug loads, the most common and important ones in term of energy consumption identified by ECOS’ field monitoring research, also in agreement with LBNL classification, were considered for this analysis. In general, miscellaneous equipment are categorised as following:

Audio/visual (television, video player/recorder, computer projector, overhead projector) Telephony (speaker phone, answering machine, phone jack) Business Equipment (Portable HVAC such as personal space heater, personal fan…, Food and

beverage such as coffee maker, kettle, microwave oven, vending machine at room temperature, hot beverage dispenser, water cooler, bottled water tap hot and cold… etc.)

3.1.3 Characteristics

Controllable/Non-controllable

Office plug load can be classified as controllable and non-controllable depending on their function. Non-controllable loads refer to loads, which can’t be switched off due to business operation requirements or security reason. Figure 7 provides examples of non-controllable equipment. Controllable plug loads are loads, which can be switched when occupants are not using them, and switching them off does not compromise safety or security. Controllability of certain plug loads is hard to be determined. For example, battery chargers should be able to be switched off when they are in the standby mode, but not when they are in active mode. For energy savings analysis, the study assumed that those plug loads wouldn’t be connected to the controlled plug load circuits and won’t generate energy savings. The CASE team classified each office device using knowledge of their typical operation and usage.Figure 20 provides the list of plug loads that were considered to be controllable.

Category Equipment Rationale


Computer&Monitor Desktop Computer Have to stay on for people working remotely or for software update during non-business hours

Notebook computer Have to stay on for people working remotely or for software update during non-business hours

Thin Client Have to stay on for people working remotely or for software update during non-business hours

Office Electronics Laser Fax Need to receive messages anytime

Ethernet Hub or Switch Follow desktop usage

Miscellaneous Phone, corded (powered) Need to receive calls anytime

Clock Non-disrupted operation pattern

Refrigerator Non-disrupted operation pattern

Figure 7. Example of Essential Equipment

Operational Mode/Power State

Most office equipment has different operational mode, or power states, which are related to their operational mode. This study adopts the ECOS PIER research definitions of five different power states, and they are listed below:

Disconnected. In this state, the device is not drawing any power. This could occur when a device is unplugged, turned off with a hard switch, or turned off via a surge protector or plug strip.

Standby. This state corresponds to the lowest steady power drawn, and usually occurs when the device doesn’t perform its primary function or when it is switched off with a soft switch but is still plugged.

Sleep. This mode defines a power state between standby and idle. It is only assigned if the device has these two other power modes, and is mostly use for product types with power-saving features.

Idle. A product operates in idle when it is prepared to perform its intended function, but is not doing so.

Active. The device is performing its intended function. In some cases, products may have more than one intended function and therefore a wide range of active mode power. For example, a multifunction device demands different power levels for scanning, printing, and copying; however, when it is performing any of these functions, the device is in active mode.

In ECOS PIER study, a product was considered to be in a power state when it spends a significant and continuous period with its power consumption in a narrow range. An operating mode could include


one or more power states, and may have also included fluctuating power levels that were not considered power states.

3.2 Market Survey

The section describes the team’s survey efforts and the feedback received from stakeholder regarding:

Other code requirement regarding plug load control Current plug load control practice Dual circuit wiring Feasibility and barriers to plug load control implementation

3.2.1 Plug Load Control Standards

Different codes are already requiring or advocating the control of task lighting and plug loads. ASHRAE 90.1 is recommending it, as well as the International Green Construction Code (IgCC). The ASHRAE Lighting Subcommittee developed CMP to 90.1-2007, modifying Addendum “bs”section 8.4.2, labelled “Automatic Receptacle Control”. The revised language is as follows:

“At least 50% of all 125 volt 15- and 20-Ampere receptacles, including those installed in modular partitions, installed in the following space types:

a. Private offices b. Open offices c. Computer Classrooms

shall be controlled by an automatic control device that shall function on:

a. a scheduled basis using a time-of-day operated control device that turns receptacles off at specific programmed times - an independent program schedule shall be provided for areas of no more than 25,000 ft2 but not more than one floor - or

b. an occupant sensor that shall turn receptacles off within

30 minutes of all occupants leaving a space or

c. a signal from another control or alarm system that indicates the area is unoccupied.

Exceptions: Receptacles for the following shall not require an automatic control device:

a. Receptacles specifically designated for equipment requiring 24 hour operation. b. Spaces where an automatic shutoff would endanger the safety or security of the room or building

occupant(s).”

The IgCC also developed plug load control requirements. This is a technical requirement which doesn’t specify implementation means. It was thought rather in the framework of soft-wire control technologies such as timer or occupancy sensor on plug strips or smart strips rather than hard wiring control technologies. The code language is the following:

“609.6 Plug load controls. Receptacles and electrical outlets controlled by an occupant sensor or time switch shall be provided in accordance with all of the following:

1. In Group B office spaces without furniture systems incorporating wired receptacles, at least one switched receptacle shall be provided for each 50 square feet.


2. In Group B office spaces with furniture systems incorporating wired receptacles, at least one switched circuit shall be provided at each electrical outlet used for powering furniture systems.

3. In classrooms in Group B and Group E occupancies, at least four switched receptacles shall be provided in each classroom.

4. In copy rooms, print shops, and computer labs, not less than one switched receptacle shall be provided for each data jack.

5. In spaces with an overhead cabinet above a counter or work surface, not less than one switched receptacle shall be provided for each work surface.

609.6.1 Distribution and marking. Controlled receptacles and electrical outlets shall be distributed in a reasonably uniform pattern throughout each space. Controlled receptacles shall be marked to differentiate them from uncontrolled receptacles.

609.6.2 Furniture systems. Furniture systems incorporating wired receptacles shall include at least two receptacles at each workstation that are connected to a controlled circuit.

609.6.3 Computer office equipment. Computer monitors, plug in space heaters, air purifiers, radios, computer speakers, coffee makers, fans, and task lights located in spaces with controlled receptacles shall be plugged into controlled receptacles.

609.6.4 Audio and visual systems. Displays, projectors, and audio amplifiers in Group B and Group E classrooms, conference and meeting rooms, and multipurpose rooms shall be controlled by an occupant sensor.

609.6.5 Water dispensers. Water dispensers that utilize energy to cool or heat drinking water shall be controlled by time switch controls.

609.6.6 Refrigerator and freezer cases. Lighting integral to vending machines and refrigerator and freezer cases shall be controlled by an occupant sensor or a time switch.”

3.2.2 Industry Survey

Respondent Profile

The pool of electrical designers and contractors surveyed was diversified. Half of the respondents were electrical designers, while the other half were electrical contractors, operating in every area of California. The total number of participants was 12. Half of them have worked on more than 100 office wiring projects, and 65% have worked on more than 50 office wiring projects. The other respondents were also experienced in office wiring (they worked on 10 to 50 office wiring projects).

Wiring practice

Bringing two separate circuits to a private office is done in about a quarter of the office projects wired this way. The main reason for feeding private offices with only one circuit is typically budget constraint. The general rule for private office wiring is to bring 3 circuits to feed 3 to 4 offices. Workstations in open spaces are very rarely served by two independent circuits (only 25% of them are). Most of the respondents agreed that bringing two circuits to a private office or a workstation is a better practice. They argued that it provides flexibility in terms of which equipment can be used at the workstation, and that putting computers and printers on a separate circuit is preferable.


Circuit Controls

No major concerns were voiced about implementation of central timer for task light and plug control. Designers and contractors noted that some circuits would have to remain uncontrolled. Some stressed that this solution may not be widely adapted for businesses which require flexibility, for instance businesses not on a 8am-5pm schedule, or when some workstations need to be switched on while others can be turned off. One respondent was worried about additional cost and complexity while doing business in California, and would rather see this requirement adopted at the federal level.

Apart from cost concerns, comments on the occupancy sensor control strategy are related to implementation considerations. Survey respondents stressed the importance of the equipment quality, in order to detect slight movements and adjust the time delay to avoid disruption. They also suggested that the receptacles would have to be color-coded, and that clocks and some other equipment would have to remain uncontrolled.

While there was little resistance to this proposal, these strategies are not commonly put into practice in the field. Forty two percent (42%) of the respondent replied having experience installing central timer control for office plug loads. The occupancy strategy seemed more common, as 67% of respondents reported having experience with it in office spaces.

In addition to applying central control or occupancy control, some respondents recommended using personal controlled outlet (with either a timer or an occupancy sensor) or occupancy sensor integrated into the task light to avoid wiring configuration change as alternatives.

3.3 Task Light and Plug Load Control Strategies

Significant energy savings can be achieved by switching task lights and plug loads off when not in use. The control strategy requires the ability to control the circuits with these loads separately from non-controlled circuits for emergency and essential plugs. Hence, each office space must be served by at least two independent circuits, with a dual circuit wiring layout. According to the industry survey described in the previous section, this wiring layout is easy to implement, and is already used in 46% of office building projects. Dual circuit wiring requires the plugs to be labelled according to their circuit connection. This practice doesn’t present any implementation issue according to interviewed electrical designers, contractors and system manufacturers.

In general, electrical circuits dedicated to plugs (120 V) can be controlled in the same way as overhead lighting circuits. Controlling task lights and plug loads can hence be done with a variety of lighting control products in the market, be it central lighting control panel, controllable breaker panels or occupancy sensors. In addition, some manufacturers are now marketing products specifically developed for plug load control to respond to the growing concern regarding plug load consumption. Electrical designers, contractors, building managers and building officials are familiar with the design, installation, operation and equipment for plug load control which are similar to lighting control strategies developed on a regular basis due to current lighting code requirements. Hence, there are no infrastructure or skill barriers to plug load control implementation. Adequate products depend on the desired control granularity. Building level control is easier to implement than workstation level control, but this latter strategy can yield additional savings due to the extended number of hours equipment is switched off.

This CASE study investigated different ways of achieving task lights and plug load control at two levels: one at the building level, and a finer-grained control at the workstation level. After examining

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3.3.2 Available Products Two types of products are suitable for task light and plug load central control: Lighting control panels and controllable breaker panels, while occupancy sensors are suited for workstation control.

Central Control Panels

Lighting control panels are primarily developed for lighting control, but they can be used for plug control as well, as they can control either 120V or 277V circuits. They use relays to switch circuits off. These relays can be controlled by an astronomical timer clock, building management system signal, occupancy sensors or other inputs. Most control panels on the market now are compatible with BACNet, LonWorks, DMX512, and other building management communication protocols. They all come with manual override to ensure services can be provided whenever needed, and most of them are Title 24 compliant certified. These panels usually come in three sizes, the most common sizes being 8, 30 and 48 relays. The number of circuits that can be controlled by one panel ranges from 8 to 48. Hence, most buildings required more than one panel. In this case, panels can be networked, with only one logic controller for the whole network to avoid controller logic redundancy. The number of panels in the network varies from 10 to 128 depending on the manufacturer and the product line. Most of the products can achieve lighting and plug control at the same time, as they can deal with mixed loads (120V and 277V) when using a voltage barrier.

Controllable Breaker Panels

Controllable breaker panels perform two functions at the same time. They protect the circuit from power surge, and they can switch them off depending on the controller logic. They are made of regular breakers, to which control relays are added. A controllable breaker panel can mix controlled loads and uncontrolled loads. Usually, the number of controlled breakers in a panel comes in multiples of four. The number of circuits in a panel ranges from to 4 to 42, the usual panel size being 18, 30 and 42 circuits. Like lighting control panels, they are compatible with BACNet, LonWorks, DMX512, and other common building management communication protocols, have manual overrides, and use the same control inputs as lighting control panels. They also can form networks; the number of panels in a network can go up to 12, the average being 8 panels. Some controllable breaker panels can also accept mixed loads (120V and 277V).

Figure 10 lists a sample of lighting control products to demonstrate product availability.

Product Type

Manufacturer Product Name

Lighting Control

Intelligent Lighting Control Light Master

Leviton e EZMax / ZMax


Panel Lighting Control and Design GR2400 Quintessence

Lightholier/Philips LyteSwitch

Lutron LCP128

Siemens LCP3000EZ System

Wattstopper Lighting Integrator

Breaker Panel

Cutler Hammer Power-R-Command

Lighting Control and design GR2400 SmartBreaker

Lutron XPS

Schneider Square D PowerLink

Siemens I-3 Control Technology P1 series

Synergy lighting control Synergy Controllable Breaker Panel

Figure 10. Central Control Products

Occupancy Sensor

Two occupancy sensor products can be used to achieve workstation level plug load control. A simple infra-red occupancy sensor switch is suitable, or more sophisticated products which feature an occupancy sensor linked to a control box can be used to control both overhead lighting and plug loads.

Passive infra-red technologies are the best suited sensor technology as it performs well in small, enclosed spaces with direct sensor’s field view. In addition, they tend to be less expensive than other technologies.

Occupancy sensors can be mounted in different ways. For workstation control purpose, a wall switch is most appropriate, is easy to install, and doesn’t require much wiring or a power pack. Wall switch occupancy sensors provide a direct manual override and typically cover a small area. Corner mounting can also be practical, in particular for conference room application. The Passive Infra-red (PIR) wall switch products can cover an area up to 500 sf, and have a time delay which can be programmed between 15 seconds to 30 minutes.

Due to the emerging demand for load control in offices, some manufacturers have developed comprehensive products which control both overhead lighting, task lights and plug loads at the room level. The occupancy sensor is connected to a small relay box which controls the different circuits serving the room.

Figure 11 lists the manufacturers and products lines for occupancy sensors and control systems.


Product Type Manufacturer Product Name

Infrared wall switch occupancy sensor

Cooper Controls Greengate OMC-P-0450-R

Enerlites WOSS15-W

Heath Zenith Lighting SL-6107-WH

Leviton OSC04-I0W

Lutron LOS-CIR-450-WH

SensorSwitch CM-9

Wattstopper PW100I

Occupancy sensor load control system

Legrand Wiremold Convia

Lutron Maestro Wireless

Wattstopper Room Controller

Figure 11 Occupancy Sensor Products

3.3.3 Central Timer Control Design

The central control option seeks to control task lights and plug loads using a central control panel. Non-essential electrical circuits are connected to controllable relays which switch them off either with a timer with a set schedule programmed by the building manager, with a signal received from a building management system, a security alarm system, occupancy sensors or other inputs. This panel can control an entire building, a floor or a space depending on the wiring constraint, the size of the building and the building wide plug load control strategy. Different panel types can be used to achieve this purpose, these options are presented below.

In most case, implementing dual circuit design doesn’t require significant equipment investment. Existing circuit protection and control equipment can accommodate dual circuit control by extending the panel capacity. Hence, it only requires an upgrade of equipment that would otherwise have been installed in order to control overhead lighting per current Title 24 requirements.

Different dual circuit control design options can answer specific building needs and user preferences. These different options are presented below, along with the baseline used to assess the energy savings potential and incremental cost of each dual circuit control option. These baselines are designed per 2008 Title 24 requirements, implying among other things that overhead lights would have been controlled to be switched off during non-business hours and that manual override would be provided. Four different baselines are presented below.

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3.4 Energy Analysis

The analysis goal is provide energy savings for the three levels of plug load controls for both prototype office buildings. The general analysis methodology were explained in section Error! Reference source not found.. This section provides detailed calculation assumptions and analysis results.

3.4.1 Task Lighting and Plug Load Operation and Control Parameters

According to the formulae provided in section 2.4, energy savings depend on the following parameters:

Controllable Plug Load

Certain office equipment cannot be interrupted event during non-business hours. For example, fax machines need to be in operation all the time and computers need to be connected for remote access or scheduled system upgrade during night. For energy savings assessment, the CASE study only considered plug load that can be safely switched off without affecting equipment functions and office operation. Figure 20 provides the list of controllable plug loads based on the criteria defined in section Error! Reference source not found., as well as the corresponding control technologies. Central timer controls can turn off all the listed plug loads when they are connected. Occupancy sensor controls are only considered to be effective to plug loads in private offices, open-space cubicles, and conference rooms.

Plug load density and energy consumption in different power states They were obtained from the LBNL study and ECOS PIER research reports and listed in Figure 21.

Building size and configuration Section Error! Reference source not found. provides detailed information of the two office building prototypes

Percentage of the time spent in these different power states during non-business hours and when occupants are away from their desk or out of office The LBNL and ECOS PIER studies are the only data sources that provide relative comprehensive usage pattern statistics of task lighting and plug loads. The LBNL study measured night time operation statistics for computer and office printing equipment. The ECOS PIER study provided averaged daily usage statistics for all plug loads. Based on the two studies, we developed task lighting and plug load power state status during business hours and non-business hours, as shown in . When data are not available, conservative assumptions are made.

Office operation schedule and private office/open-space cubicle/conference room occupancy Office business hours are based on general office working schedules. For private office/open-space cubicle/conference room occupancy, the CASE team considered average away-from-desk time for events such as lunch break, meetings, early leave, etc., and out-of-office time for events such as vacation, sick leave, business travels, work at home, jury duty, and other personal leaves. Figure 22 lists all assumptions of office operation schedules and employee working schedules.


Plug Load Central Timer Control

Occupancy Sensor Control

Private Office / Cubicle

Conference Room

Task Lighting Lamp, Desk attachment Y Y

Lamp, Table Y Y Monitor CRT Y Y LCD Y Y Printing/Imaging Equipment Laser MFD Y Inkjet MFD Y Laser printer Y Inkjet printer Y Wide Format Printer Y Document Scanner Y Audio /video Television, LCD Y Y DVD player Y Y Video Projector Y Y Speakers Y Y Subwoofer Y Y CD Player Y Y Computer Speakers Y Y Y Portable Stereo Y Y Portable CD player Y Y Table Radio Y Y Other Adding machine Y Shredder Y Stapler Y Typewriter, Electric Y Fan, portable Y Y Space heater, portable Y Y Kitchen Appliance Coffee Grinder Y Coffee Maker Y Toaster oven Y Microwave oven Y Water dispenser Y Vending machine Y Hot beverage dispenser Y

Figure 20 Controllable Plug Load for Timer and Occupancy Sensor Controls


Plug Load

Active

Idle

Sleep

Stan

db

y

Density (unit/person)

Power Density (w/sf)

Small Office

Large Office

Small Office

Large Office

Task Lighting Lamp, Desk attachment

35.4 23.2 0.57 0.5 0.5 0.06 0.07

Lamp, Table 41.7 13.4 0.91 1 1 0.14 0.17 Monitor CRT 70.6 64.2 45.86 2.6 0.21 0.23 0.05 0.07 LCD 34.2 26.4 6.19 0.88 0.99 1.07 0.11 0.15 Printing/Imaging Laser MFD 75.7 26.1 5.44 5.45 0.01 0.01 0.00 0.00 Inkjet MFD 26.0 11.1 4.66 0.04 0.04 0.00 0.00 Laser printer 130.1 19.0 11.37 0.26 0.26 0.11 0.14 Inkjet printer 64.0 6.75 4.68 2.69 0.24 0.2 0.05 0.05 Wide Format Printer 86.8 28.6 5.62 0.048 0.04 0.01 0.01 Document Scanner 10.1 4.03 0.05 0.05 0.00 0.00 Audio /video Television, LCD 58.2 3.14 0.04 0.04 0.01 0.01 DVD player 80.0 1.28 0.02 0.04 0.01 0.01 Video Projector 181.9 9.76 4.56 0.02 0.04 0.01 0.03 Speakers 32.0 10 3 1 0.04 0.08 0.00 0.01 Subwoofer 200.0 6.96 0 0.01 0.00 0.01 CD Player 8.3 2.06 0 0.02 0.00 0.00 Computer Speakers 6.0 2.43 1.66 1 1 0.02 0.02 Portable Stereo 7.5 3.31 0.88 0.02 0.01 0.00 0.00 Portable CD player 18.0 2.95 1.27 0.02 0.01 0.00 0.00 Table Radio 2.8 1.4 0.2 0.2 0.00 0.00 Other Adding machine 3.6 3.57 1.58 0.04 0.04 0.00 0.00 Shredder 78 0.77 0.04 0.02 0.01 0.01 Stapler 2 0.81 1.22 0.04 0.02 0.00 0.00 Typewriter, Electric 7 3.38 0.02 0.02 0.00 0.00 Fan, portable 30 0.63 0.1 0.2 0.01 0.03 Space heater, portable 938 1.03 0.1 0.2 0.31 0.78 Kitchen Appliance Coffee Grinder 120.0 1.25 0.21 0.2 0.01 0.08 0.01 Coffee Maker 464 40.3 1.77 0.1 0.01 0.15 0.02 Toaster oven 1058 0.03 0.04 0.02 0.14 0.09 Microwave oven 1620 3 0.08 0.02 0.06 0.14 Water dispenser 90 1 0.08 0.01 0.00 0.00 Vending machine 205 1 0.04 0.01 0.00 0.01 Hot beverage dispenser

1650 75 0 0.01 0.03 0.07

Figure 21 Plug Load Density and Power States


Annual Office Hours

Number of weekend days 104

Number of holiday 10

Number of business days 251

Average business hours/day 12

Business hours 3012

Non-business Hours (Timer control hours) 5748

Annual Private Office/Work Station Hours Number of vacation days 15

Number of sick/personal leave days 8

Number of business travel/work-at-home days 5

Annual in-office days 223

Annual out-of-office hours 336

Average hour in office per day 9

Average lunch/break hours/day 1

Average away-from-desk meeting hours/day 1

Annual away-from-desk hours 1115

Annual OC controlled hours 1451

Annual Conference Room Hours

Average occupied hours per day 5

Annual un-occupied hours during business hours 1757

Figure 22 Office Operation and Occupant Working Schedule Assumptions


Plug Load Active Idle Sleep Standby Disconnect

Task Lighting Lamp, Desk attachment 5% 0% 0% 5% 90%

Lamp, Table 5% 0% 0% 2% 93% Monitor CRT 10% 15% 0% 35% 40% LCD 10% 15% 0% 35% 40% Printing/Imaging Equipment Laser MFD 0% 28% 0% 45% 27% Inkjet MFD 0% 28% 0% 70% 2% Laser printer 0% 35% 0% 45% 20% Inkjet printer 0% 0% 0% 60% 40% Wide Format Printer 0% 0% 0% 75% 25% Document Scanner 0% 0% 0% 95% 5% Audio /video Television, LCD 0% 0% 0% 34% 66% DVD player 0% 0% 0% 100% 0% Video Projector 0% 0% 5% 64% 31% Speakers 0% 37% 2% 40% 21% Subwoofer 0% 100% 0% 0% 0% CD Player 0% 0% 0% 95% 5% Computer Speakers 0% 90% 0% 4% 6% Portable Stereo 0% 5% 0% 86% 9% Portable CD player 0% 8% 0% 75% 17% Table Radio 0% 0% 0% 84% 16% Other Adding machine 0% 40% 0% 37% 23% Shredder 0% 0% 0% 60% 40% Stapler 0% 48% 0% 50% 2% Typewriter, Electric 0% 44% 0% 50% 6% Fan, portable 0% 0% 0% 80% 20% Space heater, portable 0% 0% 0% 99% 1% Kitchen Appliance Coffee Grinder 0% 45% 0% 25% 30% Coffee Maker 0% 0% 0% 80% 20% Toaster oven 0% 0% 0% 33% 67% Microwave oven 0% 0% 0% 100% 0% Water dispenser 5% 0% 0% 95% 0% Vending machine 0% 0% 0% 100% 0% Hot beverage dispenser 0% 0% 0% 100% 0%

Figure 23 Plug Load Operation Status – Non-Business Hours



Task Lighting Lamp, Desk attachment 49% 0% 20% 32%

Lamp, Table 33% 0% 14% 55% Monitor CRT 55% 15% 15% 15% 0% LCD 55% 15% 15% 15% 0% Printing/Imaging Equipment Laser MFD Inkjet MFD Laser printer Inkjet printer Wide Format Printer Document Scanner Audio /video Television, LCD DVD player Video Projector Speakers Subwoofer CD Player Computer Speakers 4% 87% 0% 4% 5% Portable Stereo 9% 22% 86% Portable CD player 15% 11% 75% 0% Table Radio 47% 84% Other Adding machine Shredder Stapler Typewriter, Electric Fan, portable 3% 80% 17% Space heater, portable 3% 99% Kitchen Appliance Coffee Grinder Coffee Maker Toaster oven Microwave oven Water dispenser Vending machine Hot beverage dispenser

Figure 24 Plug Load Operation Status – Away-from-desk

Greyed rows indicated that the corresponding plug loads are not controlled



Task Lighting Lamp, Desk attachment

Lamp, Table Monitor CRT LCD Printing/Imaging Equipment Laser MFD Inkjet MFD Laser printer Inkjet printer Wide Format Printer Document Scanner Audio /video Television, LCD 47% 34% 19% DVD player 100% Video Projector 17% 5% 64% 14% Speakers 20% 37% 2% 40% 1% Subwoofer 100% CD Player 15% 95% Computer Speakers Portable Stereo Portable CD player Table Radio Other Adding machine Shredder Stapler Typewriter, Electric Fan, portable Space heater, portable Kitchen Appliance Coffee Grinder Coffee Maker Toaster oven Microwave oven Water dispenser Vending machine Hot beverage dispenser

Figure 25 Plug Load Operation Status – Empty Conference Room

Greyed rows indicated that the corresponding plug loads are not controlled


3.4.2 Office Building Prototypes

In order to assess the cost-effectiveness of each control option, office prototypes had to be developed. The CASE study used two office building prototypes from on the DEER (Database for Energy Efficient Resources), which classified the office building stock into two categories, small and large, using a building square footage threshold of 30,000 sf. Office layout was developed for each prototype based on typical office building design and was checked by registered architects.

Small Office Building

The DEER small office building prototype is a 2 story 10,000 sf building, with a rectangular footprint (50ft×100ft). Based on the space breakdown and space occupant density listed respectively in and Figure 27 , it is estimated that 33 employees work in this building. The first floor is made of a lobby with reception desk, stairs and elevator, a large open-space with 6 cubicles in the building core surrounded by 9 private offices and a conference room located at the perimeter of the building. The restrooms, copy room, kitchen and mechanical room can be found on the South perimeter. The first floor host 15 employees. The second floor has a similar setting, with an additional cubicle in the core of the building, hence hosting 16 employees.

Office Space (executive) Office (Executive/Private) 70%

Corridor Corridor 10%

Lobby Lobby (Office Reception/Waiting) 5%

Conference Room Conference Room 4%

Copy Room Copy Room (photocopying equipment) 2%

Restrooms Restrooms 5%

Mechanical / Electrical Room

Mechanical/Electrical Room 4%

Figure 26 Small office activity breakdown

Large Office Building

The DEER large office building prototype is a 10 story 175,000 sf building. Its shape is rectangular (175ft×100ft), and all floors have a similar layout. Based on the space breakdown and space occupant density listed respectively in Error! Reference source not found., seven hundred and thirty (730) employees are working in this building. Each floor hosts seventy-three (73) employees. A typical floor is made of 19 private offices, 54 cubicles, 2 conference rooms, 2 copy rooms, kitchen and restrooms. Each East and West perimeters host 10 private offices and a large conference room while the North and South perimeter spaces are open offices with 27 cubicles in stack of 6 or 3 at each orientation. A lobby with elevators and stairs is located in the building core, with kitchen, mechanical room and restroom on both sides. Another 9 private offices can be found in the building core.

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3.4.3 Energy Savings Analysis Results

A spreadsheet was developed to perform detailed hourly calculation of energy savings, following the calculation formulae provided in section 2.4. Annual electricity consumption reduction is summarized in Figure 29. Annual building TDV energy savings and lifecycle energy savings benefits are provided in Figure 30 and Figure 31, respectively.

Level 1 Level 2 Level 3

Small Office 0.56 0.66 0.74

Large Office 0.75 0.82 1.00

Figure 29 Annual Unit Energy Savings (kWh/sf)

Small Office Large Office

Climate Zone Level 1 Level 2 Level 3 Level 1 Level 2 Level 3

1 106,768 130,252 149,542 2,506,466 2,779,080 3,521,968

2 109,682 130,997 148,490 2,574,698 2,822,689 3,496,657

3 113,399 133,907 150,741 2,661,876 2,900,431 3,549,215

4 119,729 138,725 154,325 2,810,163 3,031,101 3,632,653

5 122,793 141,083 156,103 2,882,161 3,094,922 3,674,324

6 125,041 142,275 156,430 2,934,921 3,135,418 3,681,484

7 130,432 147,154 160,888 3,061,348 3,255,897 3,785,878

8 130,172 145,803 158,639 3,055,252 3,237,176 3,732,552

9 130,417 145,617 158,099 3,060,684 3,237,641 3,719,347

10 130,074 145,320 157,840 3,052,593 3,230,069 3,713,196

11 129,952 145,925 159,043 3,049,857 3,235,718 3,741,894

12 128,090 144,740 158,415 3,006,187 3,199,852 3,727,449

13 125,343 142,807 157,152 2,941,786 3,144,873 3,698,177

14 120,538 138,933 154,043 2,829,037 3,042,882 3,625,484

15 115,835 135,567 151,772 2,718,810 2,948,191 3,572,837

16 111,030 132,461 150,067 2,606,167 2,854,993 3,533,218

Figure 30 Annual TDV Energy Savings (kBtu/yr)



Climate Zone Level 1 Level 2 Level 3 Level 1 Level 2 Level 3

1 $7,087 $8,579 $9,798 $165,196 $182,622 $229,309

2 $7,280 $8,635 $9,740 $169,685 $185,554 $227,909

3 $7,527 $8,831 $9,894 $175,426 $190,692 $231,480

4 $7,947 $9,155 $10,141 $185,184 $199,325 $237,170

5 $8,150 $9,313 $10,263 $189,932 $203,553 $240,017

6 $8,300 $9,396 $10,290 $193,410 $206,246 $240,615

7 $8,657 $9,721 $10,589 $201,735 $214,193 $247,558

8 $8,640 $9,634 $10,446 $201,334 $212,986 $244,172

9 $8,656 $9,623 $10,412 $201,677 $213,011 $243,336

10 $8,633 $9,603 $10,394 $201,141 $212,508 $242,921

11 $8,625 $9,641 $10,470 $200,967 $212,869 $244,732

12 $8,502 $9,560 $10,425 $198,091 $210,490 $243,698

13 $8,319 $9,430 $10,337 $193,850 $206,850 $241,671

14 $8,000 $9,170 $10,125 $186,422 $200,107 $236,760

15 $7,688 $8,943 $9,967 $179,166 $193,843 $233,127

16 $7,370 $8,732 $9,844 $171,750 $187,659 $230,295

Figure 31 Lifecycle Benefits

3.5 Cost Analysis

The section provides detailed estimation of incremental costs for the three levels of building task lighting and plug load controls, as described in section Error! Reference source not found.. Costs from following items are considered:

Incremental cost of control panels for central timer controls Cost for addition of occupancy sensor controls Cost for upgrade of dual circuit wiring Labor cost for control system installation and configuration


3.5.1 Component Costs

Control Panel for Central Timer Control

The control equipment and wiring) costs and installation costs, which depends mostly on the number of circuits to be controlled, by central control panels or occupancy sensors.

The equipment required for circuit protection and for overhead lighting and task light/plug load circuit control was determined for each base case and related option (as defined in section 3.3.3), based on the number and type of circuits for each office zone, and on the space layout constraints.

Typical circuit protection practice sets 120 ft as the maximum distance from each end of circuit outlet to the circuit breaker due to voltage drop. This practice dictates the number of breaker panel systems to be used for each prototype. The lighting control devices are usually networked, and only one logic controller is used for the entire network. Typical practice places system controls at the same location on each floor, and network each floor using vertical electrical shaft.

The small office is served by two breaker and control panel systems, one on each floor. The first floor hosts the logic controller for overhead lighting control used for the second floor system. Each floor of the large office is served by two systems due to the 120 ft maximum wiring limitation. Two different control networks are used, one for each side of the building. Hence, two logic controllers are required for the large office prototype.

For each system, the controllable breaker or relay panel size was determined including a 20% extra space for future expansion purpose as commonly done in the field.

The sizing estimates were done for two cases:

Low Estimate (building served by fewer electrical circuits) High Estimate (building served by more electrical circuits)

Manufacturers were surveyed to assess the cost of standard size controllable breaker panels and control relay panels (8, 24, 42 relays or breakers) for both master (include the logic controller) and slave panels (without logic controller), as shown in Figure 32.

The panel system cost for each option for each prototype was then determined by interpolating these costs based on the number of the required additional controllable breakers or relays.

Panel Type Controller 8 relays/breakers 24 relays/breakers 42 relays/breakers

Lighting Control/Relay Panel

Master $ 2,305 $ 3,085 $ 3,960

Slave $ 1,495 $ 2,305 $ 3,215

Controllable breaker Panel

Master $ 1,090 $ 2765 $ 4,650

Slave $ 930 $ 2,335 $ 3,915

Figure 32 Control Panel Costs


3.5.2 System Cost

Level 1 Control

This level control requires all task lighting and plug loads be controlled by control panels with timer control capabilities. The number of secondary circuits for control is calculated based on total controllable plug loads, including all task lighting loads, in the building. The control panel upgrade requirements are summarized in Figure 33 and the associated incremental costs are summarised in Error! Reference source not found.. The central timer control doesn’t affect the number of circuits in the building. It only modifies the wiring layout resulting in longer wiring. The additional wiring length was assessed for each prototype by designing the wiring layout according to office layout. The result is summarized in Figure 34 provides.

The wiring material and installation costs and the labor costs were assessed using RS Means data. The cost assumptions are as followed:

2 hr for system additional relay installation 1.27 hr/ 100ft wire installation $ 86.11/hr labor cost No maintenance for 15 years


Baseline Option Small Office Large Office

Low Estimate High Estimate Low Estimate High Estimate

A 1 Add to 6 relays control panel

Add to 8 relays to control panel



B 1 Change task/plug loads breaker panel by controllable breaker panel

2 Add to 6 relays control panel




C 1 Increase controllable breaker panel by 6 controlled breakers and 14 breakers

No task/plug breaker panel

Increase controllable breaker panel by 8 controlled breakers and 16 breakers






2 Change task/plug loads breaker panel by controllable breaker panel

D 1 Replace 6 regular breaker by controllable breakers in the controllable breaker panel

Replace 8 regular breaker by controllable breakers in the controllable breaker panel



Figure 33. Central Control Strategy – Incremental Equipment Requirement


Low Estimate

High Estimate

Low Estimate

High Estimate

Additional Wire Length (ft)

252 120 3,250 2,340

Figure 34. Central Control Strategy – Additional Wire Requirement

The incremental cost for level 1 control is displayed in Figure 35.



Low Estimate

High Estimate

Low Estimate

High Estimate

A 1 $ 1,647 $ 1,864 $ 19,238 $ 31,121

B 1 $ 4,635 $ 4,612 $ 39,791 $ 48,538

2 $ 1,647 $ 1,864 $ 19,238 $ 31,121

C 1 $ 1,626 $ 1,504 $ 16,309 $ 24,049

2 $ 4,635 $ 4,612 $ 39,791 $ 48,538

D 1 $ 991 $ 775 $ 4,559 $ 5,061

Figure 35 Increment Costs - Level 1 Control


Level 2 Control

In this level of control, central timer control is used for task lights and plug load serving open spaces and common areas, including kitchen and copy room; occupancy sensors are used for private offices and conference rooms.

As for the central control strategy, the equipment required for circuit protection and for overhead lighting and task light/plug load circuit control was determined for each base case and related option, based on number and type of circuits for each office zone and on the space layout constraints. The same network configuration and number of protection and lighting control systems were assumed. The difference between the two cases relies on the number of centrally controlled plug load circuits which translates into a difference in central control equipment size. The control panel upgrade requirements are summarized in Figure 36.

In this strategy, occupancy sensors are only installed in private offices and conference rooms. Either wall switches or occupancy sensors with relay boxes can be installed.

No additional wiring is required in this strategy. Based on the prototype layouts, bringing both controlled and uncontrolled circuits in open space is feasible without longer wires. The additional wiring in the central control only strategy is related to private office wiring.

The total system upgrade cost is listed in Figure 38.



Low Estimate High Estimate Low Estimate High Estimate

A 1 Add to 1 relay control panel




B 1 Change task/plug loads breaker panel by controllable breaker panel

2 Add to 1 relays control panel




C 1 Increase controllable breaker panel by 1 controlled breakers and 17 breakers








2 Change task/plug loads breaker panel by controllable breaker panel

D 1 Replace 2 regular breaker by controllable breakers in the controllable breaker panel




Figure 36 Central Control & Occupancy Sensor Strategy - Equipment requirement

Space Type Small Office Large Office

Private Offices 18 190

Conference Room 2 20

Total 20 210

Figure 37 Central Control & Occupancy Sensor Strategy - Equipment requirement


Baseline Central Timer Control Option

Occupancy Sensor Option


Low Estimate

High Estimate

Low Estimate

High Estimate

A 1 Wall Switch $ 1,467 $ 1,852 $ 20,688 $ 27,837

Relay Box $ 3,945 $ 4,329 $ 46,699 $ 53,848

B

1 Wall Switch $ 5,318 $ 5,661 $ 49,396 $ 52,471

Relay Box $ 7,795 $ 8,139 $ 75,407 $ 78,482

2 Wall Switch $ 1,467 $ 1,852 $ 20,688 $ 27,837

Relay Box $ 3,945 $ 4,329 $ 46,699 $ 53,848

C 1 Wall Switch $ 2,309 $ 2,601 $ 26,064 $ 30,932

Relay Box $ 4,786 $ 5,079 $ 52,075 $ 56,943

2 Wall Switch $ 5,318 $ 5,661 $ 49,396 $ 54,971

Relay Box $ 7,795 $ 8,139 $ 75,407 $ 80,982

D 1 Wall Switch $ 1,375 $ 1,873 $ 11,901 $ 13,207

Relay Box $ 3,852 $ 4,350 $ 37,912 $ 39,218

Figure 38. Incremental Cost – Level 2 Control


Level 3 Control Cost

The level 3 control requires occupancy sensor control be installed in private offices, open space cubicles, and conference rooms.

Equipment type Small Office Large Office

Wall/ workstation switch

Occupancy sensor with relay

Wall/ workstation switch

Occupancy sensor with relay

Switch only strategy 37 15 770 540

Relay box and switch strategy

0 22 0 230

Figure 39 Occupancy Sensor Strategy - Equipment Requirement

Occupancy sensor control strategy doesn’t affect the wiring in the building, as circuits are split at the zone level. No additional wiring is required.

Manufacturers were surveyed to assess the cost of simple wall switches and occupancy sensor with relay box systems. These results are presented inFigure 40. The cost of wiring for occupancy sensor with relay box system is included in the manufacturer pricing.

Options Unit Price Estimated Installation Time/unit

Labor Cost/unit

Wall / workstation switch $ 25 0.35 $ 30

Occupancy sensor with relay $ 229 0.7 $ 60

Figure 40 Occupancy Sensor Strategy - Incremental Equipment Cost

The cost assumptions are as followed:

0.35 hr /wall switch installation 0.7 hr/ occupancy relay box installation $ 86.11/hr labor cost No maintenance for 15 years

The total system incremental cost is listed in Figure 41Error! Reference source not found.


Costs


Switch only strategy


Switch only strategy


Equipment Cost $ 925 $ 5,413 $ 19,250 $ 66,170

Installation Cost $ 1,115 $ 1,574 $ 23,206 $ 28,003

Total Cost $ 2,040 $ 4,947 $ 42,456 $ 51,717

Figure 41 Incremental Cost – level 3

3.6 Cost Effectiveness Analysis

Measure cost-effectiveness is determined by comparing lifecycle costs to lifecycle savings/benefits. Section 3.5 provides measure lifecycle costs. Lifetime energy savings benefits (PV of 15 years savings) are provided in Figure 31.

Compared to the incremental costs for corresponding control system incremental costs, provided in Figure 35, Figure 38, and Figure 41, lifecycle measure benefits are substantially higher than costs for all three levels of control for both small and large office buildings and for all climate zones.


4. Bibliography and Other Research List and describe each of the research studies, reports, and personal communications that provide background for this research. Identify all resources that have been pursued to further this measure. Identify all “experts” that were involved in further developing the change, all research and analysis reports and documents that were reviewed, and all industry standards that were consulted (e.g., ASTM, UL, ASHRAE test procedures, etc.). Include research that is underway that addresses the measure/change. Indicate if data or information will be produced in time to be used in this update of the Standards.

Webber C., Roberson J., Brown R., Payne C., Nordman B., Koomey J., Energy Analysis Program Environmental Energy Technologies Division Lawrence Berkeley National Laboratory, September 2001, “Field Surveys of Office Equipment Operating Patterns”, http://enduse.lbl.gov/Projects/OffEqpt.html

Roberson J., Webber C., McWhinney M., Brown R., Pinckard M., ansd Busch J., LBNL-53729-Revised, “After-hours Power Status of Office Equipment and Energy Use of Miscellaneous Plug-Load Equipment”,

Sanchez M. Webber C., Brown R., Busch J., Pinckard M., Roberson J., Environmental Energy Technologies Division Ernest Orlando Lawrence Berkeley National Laboratory University of California , February 2007, “Space Heaters, Computers, Cell Phone Chargers: How Plugged In Are Commercial Buildings?”


Roberson J., Webber C., McWhinney M., Brown R., Pinckard M., and Busch J., LBNL-53729-Revised, “After-hours Power Status of Office Equipment and Energy Use of Miscellaneous Plug-Load Equipment”,

Sanchez M. Webber C., Brown R., Busch J., Pinckard M., Roberson J., Environmental Energy Technologies Division Ernest Orlando Lawrence Berkeley National Laboratory University of California , February 2007, “Space Heaters, Computers, Cell Phone Chargers: How Plugged In Are Commercial Buildings?”

“Small office equipment in PG&E Residential territory: RASS Survey 2003 published in “Consumer Electronics: Market Trends, Energy Consumption, and Program Recommendations 2005-2010”. It was adjusted to better match small office buildings.

Chase A.., Ramos R., Pope T., December 2006, “Consumer Electronics: Market Trends, Energy Consumption, and Program Recommendations 2005-2010”

The WattStopper, “Lighting control best practice guide: Office Buildings”, http://www.nxtbook.com/nxtbooks/wattstopper/officebuildingsbpg08/

SmartDraw Communicate Visually, “Easy floor plan software”, http://www.smartdraw.com/specials/floorplans.asp


“Small office equipment in PG&E Residential territory: RASS Survey 2003 published in “Consumer Electronics: Market Trends, Energy Consumption, and Program Recommendations 2005-2010”.

Chase A.., Ramos R., Pope T., December 2006, “Consumer Electronics: Market Trends, Energy Consumption, and Program Recommendations 2005-2010”

The WattStopper, “Lighting control best practice guide: Office Buildings”, http://www.nxtbook.com/nxtbooks/wattstopper/officebuildingsbpg08/

Field Surveys of Office Equipment Operating Patterns


Documents

Measure Information Template â€“ Office Task Lighting Controls