Recommendations for 15% Above-Code Energy Efficiency Measures for Commercial Office Buildings

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ESL-TR-07-09-02

RECOMMENDATIONS FOR 15% ABOVE-CODE ENERGY EFFICIENCY

MEASURES FOR COMMERCIAL OFFICE BUILDINGS

A Project for

Texas’ Senate Bill 5 Legislation

For Reducing Pollution in

Nonattainment and Affected Areas

Soolyeon Cho

Jaya Mukhopadhyay

Zi Liu, Ph.D.

Charles Culp, Ph.D., P.E.

Jeff Haberl, Ph.D., P.E.

Bahman Yazdani, P.E.

Cynthia Montgomery

November 2007

(Revised November 2008)

ENERGY SYSTEMS

LABORATORY

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Executive Summary

This report presents detailed information about the recommendations for achieving 15% above-code energy performance for commercial office buildings complying with ASHRAE Standard 90.1-19991. To accomplish the 15% annual energy consumption reductions, ten measures were considered. After energy savings were determined for each measure, they were then placed in several groups to accomplish a minimum of 15% total annual energy consumption reduction. The analysis in this paper uses the total annual energy consumption of a simulated

commercial building to determine the 15% above-code recommendations. The analysis also reports end-use energy use, including: heating, cooling, domestic hot water use, fans, heat rejection, equipment and lighting loads, and miscellaneous loads as defined by the BEPS and BEPU reports from the DOE-2 program. Since the 15% above-code savings use annual energy cost savings, these same measures will report greater savings when compared against total heating and cooling loads, which has been used in other above-code program recommendations.

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TABLE OF CONTENTS

Table of Contents... 3

List of Tables ... 4

List of Figures ... 5

1. Base Case Building Description ... 7

1.1. Building Envelope, Lighting and Fenestration Characteristics ... 7

1.2. HVAC System Characteristics ... 7

1.3. Plant Characteristics ... 7

2. Energy Efficiency Measures (EEMs) ... 9

3. Simulation Input ... 10

4. Simulation Results ... 10

4.1. Base Case Energy Use ... 10

4.2. Energy Savings from Various EEMs ... 13

4.3. Cost Effectiveness of Various EEMs ... 14

4.4. 15% Above-Code Energy Savings ... 14

5. Description of Energy Efficiency Measures (EEMs) ... 16

5.1. Energy Efficiency Measure 1: Improved Glazing U-value (1.22 vs. 0.45) ... 16

5.2. Energy Efficiency Measure 2: Energy-Efficient Lighting (Decreasing Lighting Power Density from 1.3 W/ft2 to 1.0 W/ft2 ... 20

5.3. Energy Efficiency Measure 3: Installation of Occupancy Sensors for Lighting ... 23

5.4. Energy Efficiency Measure 4: Windows Shading (No Overhangs vs. 2.5-foot Width of Overhangs) ... 27

5.5. Energy Efficiency Measure 5: Cold Deck Reset (Constant vs. Variable) ... 30

5.6. Energy Efficiency Measure 6: Supply Fan Total Pressure (2.5 W.G. to 1.5 W.G.) ... 33

5.7. Energy Efficiency Measure 7: Chiller COP (COP 4.9 to COP 6.1) ... 36

5.8. Energy Efficiency Measure 8: Boiler Efficiency (75% to 95%)... 39

5.9. Energy Efficiency Measure 9: VSD on Chilled Water Pump ... 41

5.10. Energy Efficiency Measure 10: VSD on Hot Water Pump ... 44

6. References ... 47

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LIST OF TABLES

Table 1: Base Case Building Description ... 8

Table 2: Energy Efficiency Measures ... 9

Table 3: Specifications for an Electric/Gas Building ... 11

Table 4: Specifications for an All-Electric Building ... 11

Table 5: Summary of Annual Energy Use, Energy Costs, Savings, Implementation Costs, and Payback Periods for Houston, Texas (All-Electric) ... 13

Table 6: Summary of Annual Energy Use, Energy Costs, Savings, Implementation Costs, and Payback Periods for Houston, Texas (All-Electric) ... 13

Table 7: Cost Information of Glazing U-value (2006 RSMeans) ... 18

Table 8: Cost Information of Glazing U-value (Development of the Advanced Energy Design Guide for Small Office Buildings) ... 18

Table 9: Cost Information and Payback Calculation for the Improved Glazing U-value ... 18

Table 10: Comparison between Base Case and Improved Model Lighting ... 22

Table 11: Cost Information of Base Case and Energy-efficient Lighting Products ... 22

Table 12: Details of Spaces and Occupancy Sensors Installed for a Typical Floor ... 25

Table 13: Cost Information of Windows Overhangs ... 29

Table 14: Screw Chiller Equipment and Installation Cost Information ... 38

Table 15: Boiler Equipment and Installation Cost Information ... 40

Table 16: Variable Speed Chilled Water Pump Equipment and Installation Cost Information ... 43

Table 17: Variable Speed Chilled Water Pump Equipment and Installation Cost Information and Payback Calculation ... 46

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LIST OF FIGURES

Figure 1: Base Case Lighting Profile for a Large Commercial Building (Source: Abushakra et al., 2001). ... 7

Figure 2: Energy Use for Individual Energy Efficiency Measures (Electric/Gas) for Houston, Texas. ... 12

Figure 3: Energy Use for Individual Energy Efficiency Measures (All-Electric) for Houston, Texas. ... 12

Figure 4: Increased First Costs and Energy Savings for the Selected Measures (Electric/Gas). ... 15

Figure 5: Increased First Costs and Energy Savings for the Selected Measures (All-Electric). ... 15

Figure 6: Payback Periods for the Selected Measures (Electric/Gas). ... 15

Figure 7: Payback Periods for the Selected Measures (All-Electric). ... 15

Figure 8: Energy Use Comparison for Electric/Natural Gas Base Case (Glazing U-value, U = 1.22) and EEM (Glazing U-value, U = 0.45). ... 17

Figure 9: Energy Use Comparison for All-electric Base Case (Glazing value, U = 1.22) and EEM (Glazing U-value, U = 0.45). ... 17

Figure 10: Data Base of Fenestration Options. (http://www.pnl.gov/main/publications/external/technical_reports/PNNL-16250.pdf, p.E-1) ... 19

Figure 11: Base Case Lighting Profile for a Large Commercial Building (Source: Abushakra et al., 2001). ... 20

Figure 12: Energy Use Comparison for Electric/Natural Gas Base Case (Lighting Power Density = 1.3W/ft2) and EEM (Lighting Power Density = 1.0W/ft2). ... 21

Figure 13: Energy Use Comparison for All-electric Base Case (Lighting Power Density = 1.3W/ft2) and EEM (Lighting Power Density = 1.0W/ft2). ... 21

Figure 14: Base Case Lighting Profile. ... 23

Figure 15: Modified Lighting Profile. ... 23

Figure 16: Energy Use Comparison for Electric/Natural Gas Base Case (Without Occupancy Sensors) and EEM (Installing Occupancy Sensors). ... 24

Figure 17: Energy Use Comparison for All-electric Base Case (Without Occupancy Sensors) and EEM (Installing Occupancy Sensors). ... 24

Figure 18: Layout of Spaces for Determining Position and Number of Occupancy Sensors. ... 25

Figure 19: Energy Use Comparison for Electric/Natural Gas Base Case (No Overhangs) and EEM (2.5-foot Width of Overhangs) ... 28

Figure 20: Energy Use Comparison for All-electric Base Case (No Overhangs) and EEM (2.5-foot Width of Overhangs). ... 28

Figure 21: Cold Deck Temperature Schedule. ... 30

Figure 22: Energy Use Comparison for Electric/Natural Gas Base Case (Cold Deck Temperature Control: Constant) and EEM (Cold Deck Temperature Control: 60, 55, 55, and 85 °F). ... 31

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Figure 27: Energy Use Comparison for All-electric Base Case (Chiller COP 4.9) and EEM (Chiller COP 6.1). ... 37 Figure 28: Energy Use Comparison for Electric/Natural Gas Base Case (Boiler: Conventional, Efficiency 75%) and

EEM (Boiler: Condensing, Efficiency 95%). ... 39 Figure 29: Energy Use Comparison for Electric/Natural Gas Base Case (Constant Speed Drive on CHW pump) and

EEM (VSD on CHW Pump). ... 42 Figure 30: Energy Use Comparison for All-electric Base Case (Constant Speed Drive on CHW pump) and EEM

(VSD on CHW Pump). ... 42 Figure 31: Energy Use Comparison for Electric/Natural Gas Base Case (Constant Speed Drive on HW pump) and

EEM (VSD on HW Pump). ... 45 Figure 32: Energy Use Comparison for All-electric Base Case (Constant Speed Drive on HW pump) and EEM

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1. Base Case Building Description

The base-case building simulation model in this analysis is based on specifications in ASHRAE 90.1 1999. Table 1 summarizes the base-case building characteristics used in the DOE-2 simulation model. The simulation used the DOE-2 program and the TMY2 hourly weather data for Houston. Electricity costs were $0.119/kWh, demand charges were $5.00/kW, and costs for natural gas were $8.00/MCF.

1.1. Building Envelope, Lighting and Fenestration Characteristics

The analysis was performed for a 6-story office building (89,304 ft2), with a 50% window-to-wall ratio that follows the prescriptive tables in ASHRAE 90.1-1999. Four perimeter zones and a central core zone were modeled for each floor.

Based on climate specific characteristics, the base case was modeled with a wall insulation of R-13 value and a roof insulation of R-15. The U-value of the windows in the base-case building was set at 1.22 Btu/hr ºF ft2. 2 As per ASHRAE 90.1 1999, the SHGC of the base-case building set at 0.44 for the north orientation and 0.17 for the other orientations3. Window overhangs or shading were not used. The base-case building was modeled with a lighting power density (LPD) of 1.3 W/ft2, which is the maximum value for office applications, allowed by ASHRAE 90.1-19994. The electric lighting profile was set to the recommended profile from ASHRAE’s Diversity Factor Toolkit (RP-1093), as shown in Figure 1 (Abushakra et al. 2001).

0 0.2 0.4 0.6 0.8 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Li gh ti n g P ro fi le Hours Week day Week end

Figure 1: Base Case Lighting Profile for a Large Commercial Building (Source: Abushakra et al., 2001).

1.2. HVAC System Characteristics

The base-case building model used a variable air volume (VAV) system with terminal reheat that was set to have a total supply air static pressure of 2.5 inches of water (gauge), and has a constant supply air temperature of 55 ºF.

1.3. Plant Characteristics

The base-case building has one 160 ton (1.926 MBtu/hr) screw chiller5 with a COP of 4.9, and a constant speed chilled water pump. Two options for the heating fuel type were considered: a) natural gas (natural gas hot water boiler for space heating, and natural gas water heater for service water heating) and b) electricity (electric resistance hot water boiler for space heating, and electric water heater for service water heating). In the other sections of this report, these buildings will be referred to as (a) electric/gas building and (b) all-electric building, respectively. For the electric/gas building, heating is provided by two 731 kBtu/hr hot water gas boilers6 with an efficiency of 75%.

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Table 1: Base Case Building Description

CHARACTERISTIC BASECASE ASSUMPTIONS SOURCES

Building

Building type Office

Gross area (sq. ft.) 89,304

Prototypical office building size and number of floors (Huang & Franconi, 1999, p.31)

Dimension (ft. x ft.) 122 x 122 Number of floors 6

Floor to floor height (ft.) 13 ASHRAE 90.1-1989-13.7.1 (p.105) Construction

Roof absorptance 0.7 ASHRAE 90.1-1999-11.4.2(b) (p.58)

Roof insulation R-value (hr-sq. ft.-°F/Btu) 15 ASHRAE 90.1-1999, Table B-5 (11.4.2(a)), (p.95) Wall absorptance 0.7 ASHRAE 90.1-1989-13.7.3.3 (p.106)

Wall insulation R-value (hr-sq. ft.-°F/Btu) 13 ASHRAE 90.1-1999, Table B-5 (11.4.2(a)), (p.95) Ground reflectance 0.2 ASHRAE 90.1-1989-13.7.3.3 (p.106)

U-Factor of glazing (Btu/hr-sq. ft.-°F) 1.22 ASHRAE 90.1-1999, Table B-5 (11.4.2(c)), (p.95) Solar Heat Gain Coefficient (SHGC) 0.17 ASHRAE 90.1-1999, Table B-5 (11.4.2(c)), (p.95)

Window-to-wall ratio (%) 50 Average WWR of new construction (Huang & Franconi, 1999, p.311₎

Space

Area per person (ft2_{/person) for office} _{275 (325 occupants)} _{ASHRAE 90.1-1989, Table 13-2, (p.103)}

Occupancy schedule 8am-10pm (Monday - Saturday) ASHRAE 90.1-1989, Table 13-3, (p.104) Space temperature setpoint 70°F Heating / 75°F Cooling ASHRAE 90.1-1989-13.7.6.2 (p.110) Lighting load (W/ft2) for Office 1.3 ASHRAE 90.1-1999, Table 9.3.1.1, (p.51) Lighting schedule 24 hours (Monday - Saturday) Abushakra et al., 2001, (ASHRAE RP-1093, p.61) Equipment load (W/ft2) for office 0.75 ASHRAE 90.1-1989, Table 13-4, (p.106) Equipment schedule 24 hours (Monday - Saturday) Abushakra et al., 2001, (ASHRAE RP-1093, p.62) HVAC Systems

HVAC system type VAV with terminal reheat ASHRAE 90.1-1999, Table 11.4.3A, (p.59, System2) Number of HVAC units 5 Serving 5 thermal zones

Supply motor efficiency (%) 90 Kavanaugh, 2003 (p.38)

Supply fan efficiency (%) 61 ASHRAE 90.1-1989, Table 13-6, (p.108, System #5) Supply fan total pressure (in W.G) 2.5 Info. by ESL CC engineers

Plant Equipment

Chiller type Screw ASHRAE 90.1-1999, Table 6.2.1C, (p.29)

Chiller COP 4.9 ASHRAE 90.1-1999, Table 6.2.1C, (p.29)

Boiler type Hot water boiler

Electric resistance

boiler ASHRAE 90.1-1999, Table 11.4.3A, (p.59, System2) Boiler fuel type Natural gas Electricity ASHRAE 90.1-1999, Table 11.4.3A, (p.59, System2) Boiler thermal efficiency (%) 75 100 ASHRAE 90.1-1999, Table 6.2.1F, (p.31)

DHW fuel type Natural gas ASHRAE 90.1-1999, Table 7.2.2, (p.47) DHW heater thermal efficiency (%) 80 ASHRAE 90.1-1999, Table 7.2.2, (p.47)

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NATURAL GAS HEATING/NATURAL GAS DHW SYSTEM

ELECTRIC RESISTANCE HEATING / ELECTRIC DHW SYSTEM

A

1 Improved Window Performance (U-factor = 0.45 Btu/hr-sqft C)

Improved Window Performance (U-factor = 0.45 Btu/hr-sqft C) 2 Improved lighting load

(1W/sqft)

Improved lighting load (1W/sqft)

3 Occupancy sensors for lights Occupancy sensors for lights (Using occupancy schedules) 4 Shading (ft)

(From 0 ft to 2.5 ft)

Shading (ft) (From 0 ft to 2.5 ft)

B

5 Cold deck reset (Constant to variable)

Cold deck reset

(From 55F to 60:55F; 55:85F) 6 Supply fan total pressure

(From 2.5 inW.G. to 1.5 inW.G.)

Supply fan total pressure (From 2.5 inW.G. to 1.5 inW.G.)

C 7 Chiller COP (from 4.9 to 6.1) Chiller COP (from 4.9 to 6.1) 8 Boiler efficiency (75% to 90%) NA

9 VSD on chilled water loop VSD on chilled water loop 10 VSD on hot water loop VSD on hot water loop

Envelope and Fenestration Measures

HVAC System Measures

Plant Equipment Measures

2. Energy Efficiency Measures (EEMs)

A total of 10 measures were considered to achieve a 15% annual energy consumption reduction when compared to code (ASHRAE 90.1, 1999) for the electric/gas and the all-electric buildings. These measures included improved glazing U-value, decreasing lighting power density, window shading, reducing static pressure, improving chiller COP, improving boiler efficiency, cold deck reset, VSDs on chilled and hot water pumps, and occupancy sensors for lighting control. After costs were determined for each measure, they were then placed in several groups to

accomplish a minimum of 15% total annual energy consumption reduction. A list of all measures is provided in Table 2.

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3. Simulation Input

Table 3 and Table 4 list the inputs for simulating the measures in a representative office building located in Houston, Texas for an electric/gas building (Table 3) and an all-electric building (Table 4). Both systems had an electric chiller with a VAV air-handling unit. The values used for base case are presented in the first row of each of the tables. The subsequent rows present information used in each of the individual energy efficiency measures. The shaded boxes in each row indicate changes in input values of the measures being simulated.

4. Simulation Results

Table 5 and Table 6 summarize the annual energy use, energy costs7, savings (both energy and dollars),

implementation costs, and the calculated simple payback periods for the energy efficiency measures simulated for both the electric/gas building (Table 5), and the all-electric building (Table 6), for a building in Houston, Texas. In order to calculate the 15% above-code annual energy cost savings, the simulated electric and/or natural gas use was converted into total annual energy costs8.

Figure 2 through Figure 7 graphically present the results of the simulations and cost analysis. Figure 2 and Figure 3 present the impact of energy efficiency measures on different energy uses; Figure 4 and Figure 5 present the first cost and the energy cost savings for different measures; Figure 6and Figure 7show the corresponding payback period in years.

4.1. Base Case Energy Use

The total annual energy consumption for the base-case building in Houston, Texas, was 5,658 MMBtu for the electric/gas building, and 5,554 MMBtu for the all-electric building.

7_{The energy use shown was obtained from DOE-2’s BEPS and BEPU report.}

8_{This is required when simulating a code-compliant building that follows ASHRAE Standard 90.1-1999. For this analysis costs of $.119/kWh,}

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Table 3: Specifications for an Electric/Gas Building.

EEM

# Energy Efficiency Measures Glazing U-factor (Btu/hr-sqft-F) Lighting Load (W/sqft) Occupancy Sensors for Lights

Shading (ft) Cold Deck Reset (F)

Supply Fan Total

Pressure (in W.G.) Chiller COP Boiler Efficiency (%)

VSD on Chilled Water Loop

VSD on Hot Water Loop

BaseCase 1.22 1.3 None None 55 2.5 4.9 Efficiency Constant Speed Lighting Schedule

1 Glazing U-factor (Btu/hr-sqft-F) 0.45 1.3 None None 55 2.5 4.9 75 Constant Speed Constant Speed

2 Lighting Load (W/sqft) 1.22 1 None None 55 2.5 4.9 75 Constant Speed Constant Speed

3 Occupancy Sensors for Lights 1.22 1.3 Lit. Sch. = Occ.

Sch. None 55 2.5 4.9 75 Constant Speed Constant Speed

4 Shading (ft) 1.22 1.3 None 2.5 55 2.5 4.9 75 Constant Speed Constant Speed

5 Cold Deck Reset (F) 1.22 1.3 None None (60:55,55:85) 2.5 4.9 75 Constant Speed Constant Speed

6 Supply Fan Total Pressure (in W.G.) 1.22 1.3 None None 55 1.5 4.9 75 Constant Speed Constant Speed

7 Chiller COP 1.22 1.3 None None 55 2.5 6.1 75 Constant Speed Constant Speed

8 Boiler Efficiency (%) 1.22 1.3 None None 55 2.5 4.9 95 Constant Speed Constant Speed

9 VSD on Chilled Water Loop 1.22 1.3 None None 55 2.5 4.9 75 Variable Speed Constant Speed

10 VSD on Hot Water Loop 1.22 1.3 None None 55 2.5 4.9 75 Constant Speed Variable Speed

Envelope and fenestration measures

Table 4: Specifications for an All-Electric Building.

EEM

# Energy Efficiency Measures Glazing U-factor (Btu/hr-sqft-F) Lighting Load (W/sqft) Occupancy Sensors for Lights

Shading (ft) Cold Deck Reset (F)

Supply Fan Total

Pressure (in W.G.) Chiller COP Boiler Efficiency (%)

VSD on Chilled Water Loop

VSD on Hot Water Loop

BaseCase 1.22 1.3 None None 55 2.5 4.9 100 Constant Speed Lighting Schedule

1 Glazing U-factor (Btu/hr-sqft-F) 0.45 1.3 None None 55 2.5 4.9 100 Constant Speed Constant Speed

2 Lighting Load (W/sqft) 1.22 1 None None 55 2.5 4.9 100 Constant Speed Constant Speed

3 Occupancy Sensors for Lights 1.22 1.3 Lit. Sch. = Occ.

Sch. None 55 2.5 4.9 100 Constant Speed Constant Speed

4 Shading (ft) 1.22 1.3 None 2.5 55 2.5 4.9 100 Constant Speed Constant Speed

5 Cold Deck Reset (F) 1.22 1.3 None None (60:55,55:85) 2.5 4.9 100 Constant Speed Constant Speed

6 Supply Fan Total Pressure (in W.G.) 1.22 1.3 None None 55 1.5 4.9 100 Constant Speed Constant Speed

7 Chiller COP 1.22 1.3 None None 55 2.5 6.1 100 Constant Speed Constant Speed

8 Boiler Efficiency (%) 1.22 1.3 None None 55 2.5 4.9 100 Constant Speed Constant Speed

9 VSD on Chilled Water Loop 1.22 1.3 None None 55 2.5 4.9 100 Variable Speed Constant Speed

10 VSD on Hot Water Loop 1.22 1.3 None None 55 2.5 4.9 100 Constant Speed Variable Speed

Plant Equipment Measures Envelope and fenestration measures

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Figure 2: Energy Use for Individual Energy Efficiency Measures (Electric/Gas) for Houston, Texas.

Figure 3: Energy Use for Individual Energy Efficiency Measures (All-Electric) for Houston, Texas.

0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r Total 5,658 5,051 5,268 4,922 5,549 5,385 5,583 5,436 5,533 5,521 5,481 DHW 42.7 42.7 42.7 42.7 42.7 42.7 42.7 42.7 42.7 42.7 42.7 Fans 239 238 221 211 225 257 187 239 239 239 239 M isc. 201 157 200 189 191 195 199 201 201 130 178 HtRj. 250 229 245 219 234 251 246 250 250 250 250 Cooling 1,126 1,125 1,064 976 1,058 1,053 1,109 905 1,126 1,061 1,126 Heating-NG 589.9 67.9 702.1 878.5 590.4 384.2 590.6 589.9 465.8 589.9 444.4 Heating-Elec. 20.5 3.2 23.8 28.9 20.4 13.6 20.6 20.5 20.5 20.5 13.4 Equip. 1,377 1,377 1,377 1,377 1,377 1,377 1,377 1,377 1,377 1,377 1,377 Lighting 1,811 1,811 1,393 999 1,811 1,811 1,811 1,811 1,811 1,811 1,811

New Baseline (L&E Schedule from RP-1093)

Glazing U-factor

(Btu/hr-sqft-F) Lighting Load (W/sqft)

Occupancy Sensors for

Lights Shading (ft) Cold Deck Reset (F)

Supply Fan Total Pressure

(in W.G.) Chiller COP Boiler Efficiency (%) VSD on Chilled Water LoopVSD on Hot Water Loop

0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r Total 5,554 5,061 5,130 4,735 5,443 5,341 5,479 5,332 5,554 5,417 5,445 DHW 36.1 36.1 36.1 36.1 36.1 36.1 36.1 36.1 36.1 36.1 36.1 Fans 239 238 221 211 225 257 187 239 239 239 239 M isc. 201 157 200 189 191 195 199 201 201 130 178 HtRj. 250 229 245 219 234 251 246 250 250 250 250 Co oling 1,126 1,125 1,064 976 1,058 1,053 1,109 905 1,126 1,061 1,126 Heating-NG Heating-Elec. 513.1 87.2 593.9 727.1 511.2 360.5 513.6 513.1 513.1 513.1 428.3 Equip. 1,377 1,377 1,377 1,377 1,377 1,377 1,377 1,377 1,377 1,377 1,377 Lighting 1,811 1,811 1,393 999 1,811 1,811 1,811 1,811 1,811 1,811 1,811

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4.2. Energy Savings from Various EEMs

For both building types, the implementation of occupancy sensors for lighting and improved glazing U-factors had the greatest individual impact on the total annual energy consumption of the building. The implementation of occupancy sensors in the electric/gas building yields an annual energy consumption savings of 736 MBtu (13%). This same measure in the all-electric building yields a savings of 819 MBtu (14.7%). Surprisingly, the

implementation of shading strategies and reduction of the supply fan static pressure resulted in comparatively small annual savings. For the electric/gas building, the implementation of shading strategies yields an annual energy savings of 108 MBtu (1.9%). This same measure in the all-electric building yields a savings of 110 MBtu (2%).

Table 5: Summary of Annual Energy Use, Energy Costs, Savings, Implementation Costs, and Payback Periods for Houston, Texas (All-Electric).

Cooling Heating DHW Other Total kWh/yr therms/yr $/yr MBtu/yr % kWh/yr therms/yr $/yr

1,126 590 43 3,899 5,658 1,472,338 6,325 $196,566 1 Glazing U Factor (1.22 to 0.45 Btu/hr-sf-F) 1,125 68 43 3,815 5,051 1,447,640 1,106 $188,935 606 10.7% 24,698 5,219 $7,631 $95,130 - $174,150 12.5 - 22.8 2 Lighting Load (1.3 to 1.0 w/sq-ft) 1,064 702 43 3,460 5,268 1,325,451 7,447 $178,289 389 6.9% 146,887 -1,122 $18,277 $0 - $0 0.0 - 0.0 3 Occupancy Sensors Installation 976 879 43 3,024 4,922 1,172,190 9,211 $163,534 736 13.0% 300,148 -2,886 $33,032 $26,500 - $28,000 0.8 - 0.8

4 Shading (none to _{2.5 ft overhangs)} 1,058 590 43 3,859 5,549 1,440,495 6,331 $192,343 108 1.9% 31,843 -6 $4,223 $67,900 $110,000 16.1 - 26.0

1,126 590 43 3,899 5,658 1,472,338 6,325 $196,566

5 Cold Deck Reset 1,053 384 43 3,905 5,385 1,452,735 4,269 $192,679 273 4.8% 19,603 2,056 $3,887 $0 - $800 0.0 - 0.2

6

Supply Fan Total Pressure (2.5 to 1.5 in-H2O) 1,109 591 43 3,841 5,583 1,450,195 6,333 $193,608 75 1.3% 22,143 -8 $2,958 $0 - $200 0.0 - 0.1 1,126 590 43 3,899 5,658 1,472,338 6,325 $196,566 7 Chiller COP (4.9 to _6.1) 905 590 43 3,899 5,436 1,407,487 6,325 $187,848 221 3.9% 64,851 0 $8,718 $16,000 - $18,000 1.8 - 2.1 8 Boiler Efficiency 1,126 466 43 3,899 5,533 1,472,338 5,084 $195,573 124 2.2% -64,851 1,241 $993 $25,000 - $35,000 25.2 - 35.3 9 VSD on Chilled Water Pump (from Constant to VSD) 1,061 590 43 3,828 5,521 1,432,301 6,325 $191,681 137 2.4% 40,037 0 $4,885 $3,700 - $4,700 0.8 - 1.0 10 VSD on Hot Water Pump (from Constant to VSD) 1,126 444 43 3,868 5,481 1,463,265 4,871 $194,260 176 3.1% 9,073 1,454 $2,306 $4,000 - $5,000 1.7 - 2.2 Increased First Year Cost

($)

Payback

(yrs) Energy Efficiency

Measures

Energy Use (MBtu/yr) Energy Use (Utility Units) Energy Savings

EEM #

Envelope and Fenestration Measures Basecase

Basecase

Table 6: Summary of Annual Energy Use, Energy Costs, Savings, Implementation Costs, and Payback Periods for Houston, Texas (All-Electric).

Cooling Heating DHW Other Total kWh/yr therms

/yr $/yr MBtu/yr % kWh/yr therms /yr $/yr 1,126 513 36 3,879 5,554 1,627,216 0 $214,554 1 Glazing U Factor (1.22 to 0.45 Btu/hr-sf-F) 1,125 87 36 3,812 5,061 1,482,815 0 $192,644 493 8.9% 144,401 0 $21,910 $95,130 - $174,150 4.3 - 7.9 2 Lighting Load (1.3 to 1.0 w/sq-ft) 1,064 594 36 3,436 5,130 1,503,067 0 $199,237 424 7.6% 124,149 0 $15,317 $0 - $0 0.0 - 0.0 3 Occupancy Sensors Installation 976 727 36 2,995 4,735 1,387,338 0 $187,476 819 14.7% 239,878 0 $27,078 $26,500 $0 $28,000 1.0 - 1.0 4 Shading (none to 2.5 ft overhangs) 1,058 511 36 3,838 5,443 1,594,868 0 $210,233 110 2.0% 32,348 0 $4,321 $67,900 $110,000 15.7 - 25.5

Energy Use (Utility Units) Energy Savings

Basecase

EEM #

Envelope and Fenestration Measures

Increased First Year Cost

($)

Payback (yrs) Energy Efficiency

Measures

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4.3. Cost Effectiveness of Various EEMs

Figure 4 (electric/gas) and Figure 5 (all-electric) show the increased costs and annual energy cost savings from the energy-efficiency measures for lowered energy consumption for the different measures adopted. For example, in an electric/gas building with an improved glazing U-factor, the estimated first costs increased by $134,640 and saved $7,631, which represents a payback period of 12 years. In contrast, installing occupancy sensors cost $27,250, which saved $33,031, for a simple payback of less than one year. For both system types, four measures had very favorable paybacks of less than four years. These include occupancy sensors, improved chiller COP, and VSDs on the hot and chilled water pumps. Figure 6 (electric/gas) and Figure 7 (all-electric) present the payback period in years for each of the measures implemented. Shading strategies did not perform well for both building types. The average first costs of installing shading strategies were $88,000 for both building types. However, the energy savings obtained from implementing these strategies was $4,233 for the electric/gas building and $4,321 for the all-electric building. The resulting average payback periods were 21 years for both building types.

4.4. 15% Above-Code Energy Savings

Figures 8 and 9 present the 15% above-code savings charts for an electric/gas building (Figure 8) and an all-electric building (Figure 9). These charts represent the final summary presentation of the detailed information previously shown in Tables 1 to 5 and Figures 4 to 7. In Figures 8 and 9 the results are presented for Houston, Texas, which are also applicable for Brazoria, Fort Bend, Galveston, Harris, Montgomery, and Waller counties. Similar results for other non-attainment9 counties in Texas can be found in the attachment of this report or the Laboratory’s Senate Bill 5 website (eslsb5.tamu.edu).

In these figures, the upper table summarizes the results for individual measures in terms of annual energy savings (percent and dollars/year), annual demand savings (percent and dollars/year), combined savings (energy and demand in dollars/year), and the estimated costs for each measure10. The second table in each figure summarizes the results obtained by implementing combinations of measures. Results are presented in terms of combined energy savings (percent and dollars/year), combined demand savings (percent and dollars/year), combined savings (energy plus demand in dollars/year), combined implementation costs (marginal and new system costs) and simple payback periods (years). NOx emissions reductions for each of the combinations are also presented in terms of annual NOx emission savings (lbs/year) and savings during the ozone season period (OSP)11 (lbs/day). The maps of all the non-attainment and near non-non-attainment counties and specific counties for each page are included in the upper and lower figures.

For the case of an electric/gas building, combining the measures of a glazing U-value of 0.45 Btu/hr-ft2-°F and a lighting load of 1 W/ft2 in combination 1 yields a combined energy savings of 20%. Combining the measures of installing occupancy sensors and a cold deck reset in combination 2 yields a combined energy savings of 19.6%. Combination 3 consists of implementing a low glazing U-value of 0.45 Btu/hr-ft2-°F, a chiller COP of 6.1, a boiler efficiency of 95%, and a VSD on the chilled water pump which yields a combined energy savings of 16.8%.

For the case of an all-electric building, combining the measures of a glazing U-value of 0.45 Btu/hr-ft2-°F and a lighting load of 1 W/ft2 in combination 1 yields a combined energy savings of 18.5%. Combining the measures of installing occupancy sensors and a cold deck reset in combination 2 yields a combined energy savings of 19.8%. Combination 3 consists of implementing a low glazing U-value of 0.45 Btu/hr-ft2-°F, a chiller COP of 6.1, and VSDs on the chilled water pump and hot water pump which yields a combined energy savings of 15.5%.

9_{The Clean Air Act and Amendments of 1990 define a “nonattainment area” as a locality where air pollution levels persistently exceed National}

Ambient Air Quality Standards, or that contributes to ambient air quality in a nearby area that fails to meet standards. ( http://www.scorecard.org/env-releases/def/cap_naa.html)

10

The costs for measures are presented as marginal costs and new systems costs, where marginal costs represent the incremental costs to implement the measure by modifying an existing system. New system costs represent costs for newly installed measures.

11_{The Ozone Season Period (OSP) represents average daily savings during the hottest period of the year from mid-July to mid-September as}

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Glazing U Factor (1.22 to 0.45 Btu/hr-sf-F) Lighting Load (1.3 to 1.0 w/sq-ft) Occupancy Sensors Installation Shading (none to 2.5 ft overhangs) Cold Deck Reset Supply Fan Total Pressure (2.5 to 1.5 in-H2O) Chiller COP (4.9 to 6.1) Boiler Efficiency (Not Aplicable) VSD on Chilled Water Pump (from Constant to VSD) VSD on Hot Water Pump (from Constant to VSD) Min 1st costs $95,130 $0 $26,500 $67,900 $0 $0 $16,000 $25,000 $3,700 $4,000 Max 1st costs $174,150 $0 $28,000 $110,000 $800 $200 $18,000 $35,000 $4,700 $5,000 Av. 1st costs $134,640 $0 $27,250 $88,950 $400 $100 $17,000 $30,000 $4,200 $4,500 Energy Savings $7,631 $18,277 $33,032 $4,223 $3,887 $2,958 $8,718 $993 $4,885 $2,306 $0 $5,000 $10,000 $15,000 $20,000 $25,000 $30,000 $35,000 $0 $40,000 $80,000 $120,000 $160,000 $200,000 In cr e a se d Ist C o sts in D o ll a rs ( $ ) E nerg y S a v ing s in D o ll a rs ($)

Figure 4: Increased First Costs and Energy Savings for the Selected Measures (Electric/Gas).

Glazing U Factor (1.22 to 0.45 Btu/hr-sf-F) Lighting Load (1.3 to 1.0 w/sq-ft) Occupancy Sensors Installation Shading (none to 2.5 ft overhangs) Cold Deck Reset Supply Fan Total Pressure (2.5 to 1.5 in-H2O) Chiller COP (4.9 to 6.1) Boiler Efficiency (Not Aplicable) VSD on Chilled Water Pump (from Constant to VSD) VSD on Hot Water Pump (from Constant to VSD) Min 1st costs $95,130 $0 $26,500 $67,900 $0 $0 $16,000 $0 $3,700 $4,000 Max 1st costs $174,150 $0 $28,000 $110,000 $800 $200 $18,000 $0 $4,700 $5,000 Av. 1st costs $134,640 $0 $27,250 $88,950 $400 $100 $17,000 $0 $4,200 $4,500 Energy Savings $21,910 $15,317 $27,078 $4,321 $8,656 $2,916 $8,482 $0 $4,972 $3,960 $0 $5,000 $10,000 $15,000 $20,000 $25,000 $30,000 $35,000 $0 $40,000 $80,000 $120,000 $160,000 $200,000 In cr e a s e d Is t C o sts in D o ll a rs ( $ ) E n e rg y S a v ing s in D o llars ( $ )

Figure 5: Increased First Costs and Energy Savings for the Selected Measures (All-Electric).

Glazing U Factor (1.22 to 0.45 Btu/hr-sf-F) Lighting Load (1.3 to 1.0 w/sq-ft) Occupancy Sensors Installation Shading (none to 2.5 ft overhangs) Cold Deck Reset Supply Fan Total Pressure (2.5 to 1.5 in-H2O) Chiller COP (4.9 to 6.1) Boiler Efficiency VSD on Chilled Water Pump (from Constant to VSD) VSD on Hot Water Pump (from Constant to VSD) Min Years 12.5 0.0 0.8 16.1 0.0 0.0 1.8 25.2 0.8 1.7 Max Years 22.8 0.0 0.8 26.0 0.2 0.1 2.1 35.3 1.0 2.2 Av. Years 18 0 1 21 0 0 2 30 1 2 0.0 10.0 20.0 30.0 40.0 Nu m b e r o f Y e ars

Figure 6: Payback Periods for the Selected Measures (Electric/Gas).

30.0 40.0

ear

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November 2008 Energy Systems Laboratory, Texas A&M University System

5. Description of Energy Efficiency Measures (EEMs)

This section includes a description of EEMs, their impact on the energy use, increased cost of implementation, and calculations for simple payback. The energy use of the base-case building with base-case characteristics and with the EEM is also plotted. This includes annual end-use energy use (MMBtu) obtained from the BEPS report and monthly electricity use (kWh), monthly electric demand (kW), and gas use (therm) obtained from PS-B report of the DOE-2 output.

5.1. Energy Efficiency Measure 1: Improved Glazing U-value (1.22 vs. 0.45)

Base Case

As per ASHRAE 90.1 1999, the U-value of the windows in the base-case building was set at 1.22 Btu/hr-ft2-°F 12. The SHGC of the base-case building was set at 0.44 for the north orientation and 0.17 for the other orientations13. Window overhangs or shading were not used.

Decreased Glazing U-value (from 1.22 to 0.45)

To improve the glazing performance, the U-value was reduced to 0.45 Btu/hr-ft2-°F 14 from 1.22 Btu/hr-ft2-°F (ASHRAE 2004). This U-value was chosen to minimize winter-time heat loss using available commercial glazing products. The SHGC of the base-case building remained at 0.44 for the north orientation and 0.17 for the other orientations15.

Energy Savings

Figure 8 and Figure 9 compare the annual energy use of a commercial building in Houston with base-case

characteristics and with this measure. Figure 8 shows that this measure applied to an electric/gas base-case building: • Reduced the space cooling energy use from 1,126 MMBtu/year to 1,125 MMBtu/year.

• Reduced the space heating energy from 610 MMBtu/year to 71 MMBtu/year,

• Reduced the total energy use from 5,658 MMBtu/year to 5,051 MMBtu/year, i.e., 606.3 MMBtu/year of total energy savings,

• Reduced the electricity use from 1,472,338 kWh/year to 1,325,451 kWh/year, i.e., 24,698 kWh/year electricity savings,

• Reduced the gas use from 6,325 therms/year to 1,106 therms/year, i.e., 5,219 therms/year gas savings, and • Reduced the peak demand from 3,260 kW to 3,156 kW.

Figure 9 shows that this measure applied to an all-electric base-case building:

• Reduced the space cooling energy use from 1,126 MMBtu/year to 1,125 MMBtu/year, • Reduced the space heating energy from 513.1 MMBtu/year to 87.2 MMBtu/year,

• Reduced the total energy use from 5,554 MMBtu/year to 5,061 MMBtu/year, i.e., 493 MMBtu/year or total energy savings,

• Reduced the electricity use from 1,627,216 kWh/year to 1,482,815 kWh/year, i.e., 144,401 kWh/year electricity savings, and

• Reduced the peak demand from 4,183 kW to 3,238 kW.

12_{ASHRAE Standard 90.1-1999, Table B-5(Climate zone for Houston), p. 95.} 13_{ASHRAE Standard 90.1-1999, Table B-5(Climate zone for Houston), p. 95.}

14_{From Table for Climate Zone 2 from Advanced Energy Design Guide for Small Office Buildings. Although this guide was developed for small}

office buildings, i.e., up to 20,000 ft2_{, its use in this study was deemed appropriate.} 15_{As required by ASHRAE 90.1-1999, Table 5.3, p. 24. (Derived from Table B-5, p. 95.)}

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Base Case U-value = 0.45 Total 5,658 5,051 DHW 42.7 42.7 Fans 239 238 Misc. 201 157 HtRj. 250 229 Cooling 1,126 1,125 Heating-NG 589.9 67.9 Heating-Elec. 20.5 3.2 Equip. 1,377 1,377 Lighting 1,811 1,811 0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Elec. Use_U=1.22 116,407 103,987 117,148 116,562 129,450 131,079 140,746 139,404 125,622 123,857 114,388 113,679 Elec. Use_U=0.45 113,415 101,247 116,487 116,904 127,875 127,998 135,671 135,133 123,545 124,104 114,400 110,862 Demand_U=1.22 241 242 263 275 284 287 300 297 285 278 257 251 Demand_U=0.45 240 247 258 267 269 271 281 282 275 269 250 247 Ga s Use_U=1.22 1,613 1,445 405 172 167 157 159 158 151 160 308 1,433 Ga s Use_U=0.45 174 107 89 84 86 78 78 77 72 78 79 104 0 300 600 900 1,200 1,500 1,800 2,100 2,400 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 De m a n d (k W ), Na tu ra l Ga s Us e ( T h e rm /m o ) E n er g y U se (k W h /m o )

Energy Use and Demand Comparison (Glazing U-value: 1.22 vs. 0.45)

Figure 8: Energy Use Comparison for Electric/Natural Gas Base Case (Glazing U-value, U = 1.22) and EEM (Glazing U-value, U = 0.45).

Base Case _{value = 0.45}Glazing U-Total 5,554 5,061 DHW 36.1 36.1 Fans 239 238 Misc. 201 157 Ht. Rj. 250 229 Cooling 1,126 1,125 Heating - Elec. 513.1 87.2 Equip. 1,377 1,377 Lighting 1,811 1,811 0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r

Elec. Use_U=1.22 150,592 134,417 127,518 122,694 135,602 136,921 146,709 145,349 131,319 129,847 122,829 143,394 Elec. Use_U=0.45 117,969 104,330 119,424 119,705 130,732 130,650 138,339 137,782 126,053 126,788 117,061 113,980 Dema nd_U=1.22 564 400 370 285 294 296 309 306 294 287 318 461 Dema nd_U=0.45 265 252 265 272 274 276 286 286 280 273 256 253 0 300 600 900 1,200 1,500 1,800 2,100 2,400 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 De m a n d (k W ), Na tu r a l G a s Us e (T h e r m /m o ) En erg y U se (k W h /m o )

Energy Use and Demand Comparison (Glazing U-value: 1.22 vs. 0.45)

Figure 9: Energy Use Comparison for All-electric Base Case (Glazing value, U = 1.22) and EEM (Glazing U-value, U = 0.45).

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Implementation Cost

Two sources, RSMeans and Advanced Energy Design Guide (AEDG), were used to find the cost information for the improved glazing U-value. The information used in the analysis is provided in Table 9. The total additional cost for the improved U-value ranges from about $ 95,130 to $174,154. The data sources are as follows.

1) RSMeans (2006)

Table 7 shows the cost information from 2006 RSMeans. Total increased cost for the double pane clear glass is $130,969 and for the double pane low-e coating with air is $174,154.

Table 7: Cost Information of Glazing U-value (2006 RSMeans).

Type of Glass Thickness # Pane U-value (Btu/hr- ft2-°F) Mat. Cost ($/ft2) Labor Cost ($/ft2) Total Unit Cost ($/ft2) Increased Unit Cost ($/ft) Total Glass Area (ft2) Total Glazing Cost ($) Total Increased Cost ($) Code Clear plain 1/4" 1 1.025 5.65 3.16 8.81 - 13,176 116,081 0 Above-code Clear plain 1/4" 2 0.474 13.70 5.05 18.75 9.94 13,176 247,050 130,969 Above-code Clear with 1 low-e coating w/ air 1/4" 2 0.450 14.73 7.30 22.03 13.22 13,176 290,234 174,154

2) Development of the Advanced Energy Design Guide (AEDG) for Small Office Buildings (http://www.pnl.gov/main/publications/external/technical_reports/PNNL-16250.pdf, p. E-1)

This report shows the cost information for the increased glazing U-value. Figure 10 retrieved from the report shows the data of fenestration options. According to this report, the additional unit cost ($/ft2) for the increased U-value is $7.22. Therefore, the total additional cost would be $95,131 for the building.

Table 8: Cost Information of Glazing U-value (Development of the Advanced Energy Design Guide for Small Office Buildings).

U-value (Btu/hr- ft2-°F)

Additional Cost ($/ft2)

Total Glass Area (ft2)

Total Increase in Cost ($)

Code 1.22 0 13,176 0

Above-code 0.46 7.22 13,176 95,131

Table 9: Cost Information and Payback Calculation for the Improved Glazing U-value.

Fenestration Measure Total Glass Area Increased Unit Cost Total Increase Cost Referemce

(ft2) ($/ft2) ($)

Base Case

Clear single pane windows: U = 1.22 13,176 0 0 EEM Increased U-value: U = 0.45 13,176 $7.22 - $13.22 $ 95,130 - $174,154

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Figure 10: Data Base of Fenestration Options.

(http://www.pnl.gov/main/publications/external/technical_reports/PNNL-16250.pdf, p. E-1)

Payback Calculation

(a) For Electric/gas building:

Electricity cost savings = 24,698 kWh x $0.119/kWh = $ 2939.062 Gas cost savings = 5,219 therm x 0.1 (MCF/therm) x $8/MCF = $ 4592.72 Demand savings = 103.41 kW x $5.00/kW = $ 517.05

Total savings = $ 8048.832

Cost difference = $ 95,130 ~ $174,154

Simple Payback = 11.81 to 21.63 years

(b) For All-Electric building:

Electricity cost savings = 144401 kWh x $0.119/kWh = $ 17,183.719 Demand savings = 945.2 kW x $5.00/kW = $ 4726

Total savings = $ 21910

Cost difference = $ 95,130 ~ $174,154

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November 2008 Energy Systems Laboratory, Texas A&M University System 5.2. Energy Efficiency Measure 2: Energy-Efficient Lighting (Decreasing Lighting Power Density from 1.3 W/ft2

to 1.0 W/ft2

Base Case

The base-case building was modeled with a lighting power density (LPD) of 1.3 W/ft2, which is the maximum value for office applications allowed by ASHRAE 90.1-199916. The electric lighting profile was set to the recommended profile from ASHRAE’s Diversity Factor Toolkit (RP-1093), as shown in Figure 11 (Abushakra et al. 2001).

0 0.2 0.4 0.6 0.8 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Li ghti ng P rofi le Hours Week day Week end

Figure 11: Base Case Lighting Profile for a Large Commercial Building (Source: Abushakra et al., 2001).

Improved Model with Energy-Efficient Lighting

The impact of energy-efficient lighting was determined by reducing the Lighting Power Density (LPD) from 1.3 W/ft2 to 1.0 W/ft2 17. There are a number of lighting systems available to meet the LPD requirements, including fixture type, fixture size, type of lens or louver, and mounting height. However, only the lamp type and ballast type were considered in this cost analysis.

Energy Savings

Figure 12 and Figure 13 compare the annual energy use of a commercial building in Houston with base-case characteristics and with this measure. Figure 12 shows that this measure applied to an electric/gas base-case building:

• Reduced the space cooling energy use from 1,126 MMBtu/year to 1,063.5 MMBtu/year, • Increased the space heating energy from 610 MMBtu/year to 726 MMBtu/year,

• Reduced the total energy use from 5,658 MMBtu/year to 5,268 MMBtu/year, i.e., 389 MMBtu/year of total energy savings,

• Reduced the electricity use from 1472338 kWh/year to 1325451 kWh/year, i.e., 146887 kWh/year electricity savings,

• Increased the gas use from 6,325 therms/year to 7447 therms/year, i.e., 1122 therms/year increase in gas use, and

• Reduced the peak demand for July from 3260 kW to 2921 kW. Figure 13 shows that this measure applied to an all-electric base-case building:

• Reduced the space cooling energy use from 1,126 MMBtu/year to 1,063.5 MMBtu/year, • Increased the space heating energy from 513.1 MMBtu/year to 594MMBtu/year,

16_{ASHRAE Standard 90.1-1999, Table 9.3.1.1, p. 51.}

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Base Case LPD = 1W/sqft Total 5,658 5,268 DHW 42.7 42.7 Fans 239 221 Misc. 201 200 HtRj. 250 245 Cooling 1,126 1,064 Heating-NG 589.9 702.1 Heating-Elec. 20.5 23.8 Equip. 1,377 1,377 Lighting 1,811 1,393 0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Elec. Use_With 1.3 W/sq. ft. 116,407 103,987 117,148 116,562 129,450 131,079 140,746 139,404 125,622 123,857 114,388 113,679 Elec. Use_With 1.0 W/sq. ft. 105,331 94,127 105,657 104,542 116,166 117,858 126,775 125,397 112,812 110,996 102,828 102,972 Demand_With 1.3 W/sq. ft. 241 242 263 275 284 287 300 297 285 278 257 251 Demand_With 1.0 W/sq. ft. 215 212 236 248 254 257 272 270 255 251 230 221 Gas Use_With 1.3 W/sq. ft. 1,613 1,445 405 172 167 157 159 158 151 160 308 1,433 Gas Use_With 1.0 W/sq. ft. 1,881 1,695 559 182 171 161 164 163 155 167 397 1,753 0 300 600 900 1,200 1,500 1,800 2,100 2,400 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 D e m a nd (kW ), N a tu r a l Ga s us e ( T he r m /m o ) E n e r gy U se ( k W h /m o)

Energy Use and Demand Comparison (Lighting Power Density: 1.3 W/sq-ft vs. 1.0 W/sq-ft)

Figure 12: Energy Use Comparison for Electric/Natural Gas Base Case (Lighting Power Density = 1.3W/ft2) and EEM (Lighting Power Density = 1.0W/ft2).

Base Case LPD = 1W/sqft Total 5,554 5,130 DHW 36.1 36.1 Fans 239 221 Misc. 201 200 Ht. Rj. 250 245 Cooling 1,126 1,064 Heating 513.1 593.9 Equip. 1,377 1,377 Lighting 1,811 1,393 0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu/ y r

Elec. Use_With 1.3 W/sq. ft. 150,592 134,417 127,518 122,694 135,602 136,921 146,709 145,349 131,319 129,847 122,829 143,394 Elec. Use_With 1.0 W/sq. ft. 144,913 129,614 118,810 110,947 122,517 123,892 132,938 131,541 118,702 117,210 112,913 139,083 Dema nd_With 1.3 W/sq. ft. 564 400 370 285 294 296 309 306 294 287 318 461 Dema nd_With 1.0 W/sq. ft. 573 420 377 258 264 267 281 279 265 261 318 513 0 300 600 900 1,200 1,500 1,800 2,100 2,400 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 D e m a nd (kW ), N a tur a l G a s us e (T he r m /m o ) E n e rg y U se ( k W h/m o)

Energy Use and Demand Comparison (Lighting Power Density: 1.3 W/sq-ft vs. 1.0 W/sq-ft)

Figure 13: Energy Use Comparison for All-electric Base Case (Lighting Power Density = 1.3W/ft2) and EEM (Lighting Power Density = 1.0W/ft2).

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There are a number of variables that can affect the installation cost of lighting systems in order to meet the LPD requirements as described above. Some of these are fixture type, fixture size, type of lens or louver, and mounting height. The cost analysis is simplified by considering the changes in general lighting systems and whole building LPD, and assuming other costs to be the same. Table 10 shows the details of the lighting system for the two scenarios. The lighting power density of 1.3 W/ft2 can be achieved by fixtures with 3 – 34 Watt T12 lamps and magnetic ballast. To achieve the LPD of 1.0 W/ft2, similar fixtures with 3 -32Watts T8 lamps and electronic ballast are required. It was assumed that the most common light fixtures currently used in new construction is the 2x4 recessed, lay-in luminaire that would accommodate both lamp types. This fixture would also contain painted white reflecting surfaces and an acrylic, prismatic lens, and satisfy the maximum allowed power density while providing 30-50 footcandles on the work plane, depending on mounting height and/or room configuration. Finally, the cost of lighting is obtained from online sources. Table 11 shows the cost of both base-case and energy-efficient lighting products. Assuming that the other costs (including fixture cost, labor cost, and cost of wiring and accessories) are the same, there is no increased cost estimate compared to the base case.

Table 10: Comparison between Base Case and Improved Model Lighting.

Fixture Lamp Ballast Watt/lamp Watt/Fixture

Basecase F43EE

(3-48”, 34W, T-12 Lamps Fixture) F34T12 Magnetic-ES 34W 115W Energy-efficient Lighting F43ILL (3-48”, 32W, T-8 Lamps Fixture) F32T8 Instant Star Electronic 32W 85W

Table 11: Cost Information of Base Case and Energy-efficient Lighting Products.

Lamp Brand Cost/unit18 Ballast Brand Cost/unit19

Basecase F34T12 Fluorescent

Bulb Philips $1.19-$1.99

277 Volt One or Two Lamp F34T12 Magnetic Ballast Advance Transformer $11.99-$21.49 Energy-efficient Lighting F32T8 Fluorescent Bulb GE $1.29-$2.19

120-277 Volt Three Lamp F32T8 Electronic Ballast

Advance

Transformer $16.99-$24.99

Electricity cost savings = 146887 kWh x $0.119/kWh = $ 17480 Gas cost savings = -1122 therm x 0.11 (MCF/therm) x $8/MCF = - $ 987 Demand savings = 339 kW x $5.00/kW = $ 1695

Total savings = $ 18187 Cost difference = None

Simple Payback = Immediate savings

Electricity cost savings = 124149 kWh x $0.119/kWh = $ 14773.7 Demand savings = 108.7 kW x $5.00/kW = $ 543

Total savings = $ 15,317 Cost difference = None

Simple Payback = Immediate savings

18_{http://www.bulbs.com/Fluorescent_Bulbs/results.aspx}

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5.3. Energy Efficiency Measure 3: Installation of Occupancy Sensors for Lighting

Base Case

The base-case building is modeled with a lighting power density of 1.3 W/sq. ft., as required by ASHRAE 90.1-1999 (Table 9.3.1.1, p. 51). The electric lighting profile is adopted from RP-1093 Report (Large Buildings) and is shown in Figure 14.

Improved Model with Occupancy Sensors for Lighting

The energy impact from the installation of occupancy sensors for lighting is determined by specifying that the electric lighting profile is the same as the occupancy profile (Figure 15), which is adopted from ASHRAE 90.1-1989 (Table 13-3, p.104). 0 0.2 0.4 0.6 0.8 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hours Li ght ing P rof il e Weekday Saturday

Figure 14: Base Case Lighting Profile.

0 0.2 0.4 0.6 0.8 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hours M odi fi e d Li ght ing P ro fi le Weekday Saturday

Figure 15: Modified Lighting Profile.

Energy Savings

• Reduced the space cooling energy use from 1,126 MMBtu/year to 976 MMBtu/year, • Increased the space heating energy from 610 MMBtu/year to 907.4 MMBtu/year,

• Reduced the total energy use from 5,658 MMBtu/year to 4921 MMBtu/year, i.e., 735.79 MMBtu/year of total energy savings,

• Increased the gas use from 6,325 therms/year to 9211 therms/year, i.e., 2886 therms/year increase in gas use, and

• Increased the demand from 3260 kW to 3335 kW.

• Reduced the space cooling energy use from 1,126 MMBtu/year to 976 MMBtu/year, • Increased the space heating energy from 513.1 MMBtu/year to 727MMBtu/year,

Weekday

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Base Case Occupancy _Sensors

Total 5,658 4,922 DHW 42.7 42.7 Fans 239 211 Misc. 201 189 HtRj. 250 219 Cooling 1,126 976 Heating-NG 589.9 878.5 Heating-Elec. 20.5 28.9 Equip. 1,377 1,377 Lighting 1,811 999 0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Elec. Use_Without Sensors 116,407 103,987 117,148 116,562 129,450 131,079 140,746 139,404 125,622 123,857 114,388 113,679 Elec. Use_With Sensors 94,252 84,290 93,461 91,304 102,695 104,085 112,147 111,639 98,345 97,721 90,952 91,267 Demand_Without Sensors 241 242 263 275 284 287 300 297 285 278 257 251 Demand_With Sensors 245 243 271 286 296 297 308 308 294 286 256 245 Gas Use_Without Sensors 1,613 1,445 405 172 167 157 159 158 151 160 308 1,433 Gas Use_With Sensors 2,225 2,138 818 212 184 173 176 175 167 186 557 2,198

0 300 600 900 1,200 1,500 1,800 2,100 2,400 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 De m a n d (kW ), Na tur a l G a s u se (T he r m /m o ) E n e r gy U se ( k W h /m o)

Energy Use and Demand Comparison

(Lighting Control: w/o Occupancy Sensors vs. w/ Occupancy Sensors)

Figure 16: Energy Use Comparison for Electric/Natural Gas Base Case (Without Occupancy Sensors) and EEM (Installing Occupancy Sensors).

Base Case Occupancy Sensors Total 5,554 4,735 DHW 36.1 36.1 Fans 239 211 Misc. 201 189 Ht.Rj. 250 219 Cooling 1,126 976 Heating 513.1 727.1 Equip. 1,377 1,377 Lighting 1,811 999 0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r

Elec. Use_Without Sensors 150,592 134,417 127,518 122,694 135,602 136,921 146,709 145,349 131,319 129,847 122,829 143,394 Elec. Use_With Sensors 140,881 128,854 111,849 98,495 109,558 110,615 118,822 118,295 104,730 104,559 104,205 136,468

Dema nd_Without Sensors 564 400 370 285 294 296 309 306 294 287 318 461

Dema nd_With Sensors 594 442 431 297 307 307 318 318 304 296 327 535

0 300 600 900 1,200 1,500 1,800 2,100 2,400 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 D e m a nd (k W ), N a tu ra l G a s us e ( T he rm /m o) En e rg y U se (k W h /m o )

Energy Use and Demand Comparison

(Lighting Control: w/o Occupancy Sensors vs. w/ Occupancy Sensors)

Figure 17: Energy Use Comparison for All-electric Base Case (Without Occupancy Sensors) and EEM (Installing Occupancy Sensors).

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The cost analysis was based on an analysis for a typical floor (14,884 ft2/floor) of a six-story office building having 89,304 ft2 gross floor area. The area distribution and layout of spaces for the typical floor is assumed as shown in Figure 1820 and Table 1221, respectively. The type and coverage of occupancy sensors is determined from the product selection and installation guidelines22,23. These facilitated in determining the position and the number of occupancy sensors required for a typical floor. Finally, the cost of selected sensors is obtained from various sources as shown in Table 12. Table 12 also shows the cost of sensors (and power pack, if required) for a typical floor. This does not include the cost of labor and additional wiring. Thus, the total cost of sensors for a six-story office building is estimated at $27,229.

Open Office

Open Office Lobby / Open Office

Open Office Mech / Elec Conf. Conf. Copy T T up down up down

Figure 18: Layout of Spaces for Determining Position and Number of Occupancy Sensors.

Table 12: Details of Spaces and Occupancy Sensors Installed for a Typical Floor.

Space Area

Distribution

# of

sensors Remarks Brand Model Cost/unit

Total cost

Open office 45% 4 Commercial Grade

Multi-Tech, Ceiling-Mount Leviton ODC20-MRW $179.97

24_$719.88

Private office 25% 32 PIR, wall switch Leviton ODS15ID $69.9525_$2,238.40

Lobby 5% None None - - - -

Corridor 10% 4 PIR Long Range Aisle

Wall Mount + Power Pack Leviton

OSWLR-I0W +

OSP20-0D0 $150.51

26_$602.04

Conference room 4% 4 Multi-Tech 500 sq. ft.

Ceiling Mount + Power Pack Leviton

OSC05-M0W +

OSP20-0D0 $139.66

27_$558.64

Copy room 2% 1 PIR, wall switch Leviton ODS15ID $69.95 $69.95 Restrooms 5% 2 Multi-Tech 500 sq. ft.

Ceiling Mount + Power Pack Leviton

OSC05-M0W +

OSP20-0D0 $139.66 $279.32 Mechanical/

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Electricity cost savings = 300148 kWh x $0.119/kWh = $ 35,718 Gas cost savings = -2886 therm x 0.11 (MCF/therm) x $8/MCF = - $ 2,540 Demand savings = -75.42 kW x $5.00/kW = - $ 377

Total savings = $ 32,801 Cost difference = $26,500 – 28,000

Simple Payback = 0.8 – 0.85 years

Electricity cost savings = 239,878 kWh x $0.119/kWh = $ 28,545.5 Demand savings = -293.5 kW x $5.00/kW = $ -1468

Total savings = $ 27,078

Cost difference = $ 26,500 ~ $28,000

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5.4. Energy Efficiency Measure 4: Windows Shading (No Overhangs vs. 2.5-foot Width of Overhangs)

Base Case

According to the ASHRAE 90.1-1999, the base-case office building has no window overhangs.

Window Shading

The impact of the addition of window shades was considered by adding window shades to all orientations (except north) using a projection factor of 0.5, as recommended by the ASHRAE Advanced Energy Design Guide for Small Office Buildings (ASHRAE 2004). Since the windows used in the base case simulation were set to a height of 5 feet, this resulted in shade that projected 2.5 feet, which was attached at the top of the window.

Energy Savings

• Reduced the space cooling energy use from 1,126 MMBtu/year to 1058 MMBtu/year, • Increased the space heating energy from 610 MMBtu/year to 611 MMBtu/year,

• Reduced the total energy use from 5,658 MMBtu/year to 5549 MMBtu/year, i.e., 108.14 MMBtu/year of total energy savings,

• Increased the gas use from 6,325 therms/year to 6331 therms/year, i.e., 6 therms/year increase in gas usage, and

• Reduced the demand from 3260 kW to 3172 kW.

• Reduced the space cooling energy use from 1,126 MMBtu/year to 1058 MMBtu/year, • Reduced the space heating energy from 513.1 MMBtu/year to 511 MMBtu/year,

• Reduced the total energy use from 5,554 MMBtu/year to 5,443 MMBtu/year, i.e., 110.4 MMBtu/year or total energy savings,

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November 2008 Energy Systems Laboratory, Texas A&M University System Base Case 2.5 ft Overhangs Total 5,658 5,549 DHW 42.7 42.7 Fans 239 225 Misc. 201 191 HtRj. 250 234 Cooling 1,126 1,058 Heating-NG 589.9 590.4 Heating-Elec. 20.5 20.4 Equip. 1,377 1,377 Lighting 1,811 1,811 0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Elec. Use_w/o Overhang116,407 103,987 117,148 116,562 129,450 131,079 140,746 139,404 125,622 123,857 114,388 113,679 Elec. Use_w/ Overhang 114,217 101,894 114,675 113,986 126,582 128,315 137,859 136,383 122,346 120,741 112,007 111,487 Demand_w/o Overhang 241 242 263 275 284 287 300 297 285 278 257 251 Demand_w/ Overhang 237 235 256 267 277 280 291 290 275 270 250 246 Gas Use_w/o Overhang 1,613 1,445 405 172 167 157 159 158 151 160 308 1,433 Gas Use_w/ Overhang 1,619 1,457 423 169 164 154 156 155 148 157 300 1,431

0 300 600 900 1,200 1,500 1,800 2,100 2,400 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 D e m a nd (k W ), Na tu r a l G a s Us e (T he r m /m o ) E n e r gy U se ( k W h /m o)

Energy Use and Demand Comparison (Shadings: w/o Overhangs vs. w/ 2.5 ft Overhangs)

Figure 19: Energy Use Comparison for Electric/Natural Gas Base Case (No Overhangs) and EEM (2.5-foot Width of Overhangs). Ba se Ca se Overha ng 2.5ft Tota l 5,554 5,443 DHW 36.1 36.1 Fa ns 239 225 Misc. 201 191 Ht.Rj. 250 234 Cooling 1,126 1,058 Hea ting 513.1 511.2 Equip. 1,377 1,377 Lighting 1,811 1,811 0 1,000 2,000 3,000 4,000 5,000 6,000 MB tu /y r

Elec. Use_w/o Overha ng 150,592 134,417 127,518 122,694 135,602 136,921 146,709 145,349 131,319 129,847 122,829 143,394 Elec. Use_w/ Overha ng 148,518 132,596 125,286 119,999 132,619 134,044 143,707 142,212 127,932 126,617 120,214 141,122

Dema nd_w/o Overha ng 564 400 370 285 294 296 309 306 294 287 318 461

Dema nd_w/ Overha ng 552 391 367 277 286 289 300 300 283 279 312 453 0 300 600 900 1,200 1,500 1,800 2,100 2,400 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 De m a nd ( k W ), Na tu r a l Ga s Use (T he r m /m o ) En er g y U se (k W h /mo )

Energy Use and Demand Comparison (Shadings: w/o Overhangs vs. w/ 2.5 ft Overhangs)

Figure 20: Energy Use Comparison for All-electric Base Case (No Overhangs) and EEM (2.5-foot Width of Overhangs).

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Three sources were used to find the cost information of window overhangs. Table 13 summarizes the cost

information that is used in the analysis. The total additional cost for adding window overhangs is around $67,911 to $109,800. The data sources are as follows:

1. Estimation from a personal communication with Professor Larry Degelman of Texas A&M University was used to obtain the cost information of window overhangs. According to him, the increased unit cost for reinforced concrete overhangs would be $20/ft2. The total area of overhangs is 5,490 ft2, and the total increased cost will be $109,800.

2. The Business Case for Sustainable Design in Federal Facilities (U.S. DOE 2003): Appendix B

(http://www1.eere.energy.gov/femp/pdfs/buscase_appendixb.pdf, p. B-10). According to Appendix B in this report, the increased unit cost for reinforced concrete overhangs would be $12.37/ft2. The total area of overhangs is 5,490 ft2, and the total increased cost will be $67,911.

3. Actual Cost Information from a Construction (“Construction bid for louvered overhang sun shades on a fire station project in College Station, Texas,” October, 2006, Thomas Parker, AIA, Director, BRW Architects, Inc., 2700 Earl Rudder Freeway So., College Station, TX 77845, 979-694-1791): Actual construction cost information presents the increased cost for window overhangs. The type of overhang in this construction was louvered metal, which is relatively expensive compared to concrete type overhangs. The increase unit cost is $58/sq. ft., and the total increase cost will be $318,420. The cost information from this source is withdrawn for this cost information calculation.

Table 13: Cost Information of Windows Overhangs.

No. Type of Overhangs Increased Unit Costs ($/ft2) Length of Overhangs (ft) Width of Overhang (ft) Total Overhang Area (ft) Total Increased Cost ($) Source 1 3” reinforced concrete slab

20 2196 2.5 5490 109,800 Estimation from Prof. Degelman

2 3’ closed overhangs 12.37 2196 2.5 5490 67,911 http://www1.eere.energy.gov/femp/pdf s/buscase_appendixb.pdf 3 Louvered metal overhangs 58 2196 2.5 5490 318,420

Construction bid for louvered overhang sun shades on a fire station

project in College Station, Texas. October 2006.

Electricity cost savings = 31843 kWh x $0.119/kWh = $ 3789 Gas cost savings = -6 therm x 0.11 (MCF/therm) x $8/MCF = - $ 5.3 Demand savings = 87.67 kW x $5.00/kW = - $ 438

Total savings = $ 4222.4 Cost difference = $67,900 - 110000

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November 2008 Energy Systems Laboratory, Texas A&M University System 5.5. Energy Efficiency Measure 5: Cold Deck Reset (Constant vs. Variable)

Base Case

The base-case building model has constant supply air temperature of 55 °F. The DOE-2 simulation showed the yearly total energy use of 5,658 MMBtu.

Cold Deck Schedule

To further improve the performance of the cooling system, the cold deck schedule was changed from a constant 55 °F to a schedule as shown in the graph in Figure 21. This saves cooling energy by maintaining the cold deck air temperature at 60 °F when the outdoor temperature is 55 °F or lower, and maintains the cold deck temperature at 55 °F when the outdoor temperature is 85 °F or higher28. The cold deck temperature decreases linearly from 60 °F to 55 °F as the outdoor temperature increases from 55 °F to 85 °F.

52 53 54 55 56 57 58 59 60 61 35 45 55 65 75 85 95 105 Outside Air Temperature Co ld De ck Te m p e ra tu re

Figure 21: Cold Deck Temperature Schedule.

Energy Savings

Figure 22 and Figure 23 compare the annual energy use of a commercial building in Houston with base-case characteristics and with this measure. Figure 22 shows that this measure applied to an electric/gas base-case building:

• Reduced the space cooling energy use from 1,126 MMBtu/year to 1053 MMBtu/year, • Reduced the space heating energy from 610 MMBtu/year to 398 MMBtu/year,

• Reduced the total energy use from 5,658 MMBtu/year to 5385 MMBtu/year, i.e., 273 MMBtu/year of total energy savings,

• Reduced the gas use from 6,325 therms/year to 4269 therms/year, i.e., 2056 therms/year reduction in gas usage, and

• Increased the demand from 3260 kW to 3278 kW.

• Reduced the space cooling energy use from 1,126 MMBtu/year to 1053 MMBtu/year, • Reduced the space heating energy from 513.1 MMBtu/year to 361 MMBtu/year,

28_{This cold deck schedule was implemented based on settings revealed by a survey of the buildings at the Texas A&M University campus that}