ENERGY EFFICIENCY/RENEWABLE ENERGY (EERE) PROJECTS IN TEXAS PUBLIC SCHOOLS

Transcription

1 ENERGY EFFICIENCY/RENEWABLE ENERGY (EERE) PROJECTS IN TEXAS PUBLIC SCHOOLS N Jeff S. Haberl, Ph.D., P.E Zi Liu, Ph.D. Hyojin Kim Jaya Mukhopadhyay Sunglok Do Bahman Yazdani, P.E. Charles Culp, Ph.D., P.E. Juan-Carlos Baltazar, Ph.D Energy Systems Laboratory Texas A&M University 17 th Symposium for Improving Building Austin TX August 24 25, 2010

2 Outline Introduction 2 Methodology Base-Case School Model Energy Efficiency Measures Results Summary

3 Introduction Energy Saving Potential in High Performance Schools Energy use of the most efficient schools = 1/3 energy of the least efficient schools (EPA 2010) 20% to 40% energy savings in high performance schools (Im and Haberl 2006) 3 Energy Saving Potential in Texas Public Schools Average age of Texas public schools (2006 survey of Texas Comptroller of Public Accounts) - Elementary schools: 35.2 years old - Middle schools: 32.2 years old - High schools: 32.7 years old Average enrollment growth rate of Texas public schools (TEA 2009) % over the past 10-year period Huge energy saving potential in both existing and new schools in Texas from the application of high performance strategies

4 Introduction Energy Efficiency/Renewable Energy (EERE) Projects in Texas Public Schools Goal - To produce an analysis of the potential energy savings, and resultant air pollution reductions associated with the energy savings from the application of costeffective energy efficiency and renewable energy projects applied to new and existing Texas Independent School Districts (ISDs) 4 Process - Preliminary results from an analysis of the energy saving potential in new and existing Texas Independent School Districts (ISDs)

5 Methodology 5 Grouped Counties by ASHRAE /2007 Climate Zones Texas Education Agency Energy Star School SECO K-12 Energy Audit Elementary School Middle School High School Weather Zone Assigned Weather Station EPlus Benchmark School Model AEDG School Baseline Model Survey of College Station/Bryan ISDs No. of This Type of School Avg. No. of Students/This Type of School Simulation Group 1: Built Before 2000 School Model Assumptions ASHRAE Specifications Group 1: Base-Case School Model Avg. Sq. ft./this Type of School School Compliant with ASHRAE AEDG Year This Type of School Built Group 2: Built School Model Assumptions ASHRAE Specifications Group 2: Base-Case School Model Avg. Sq. ft. /Student Savings/sq. ft. Group 3: Built School Model Assumptions ASHRAE Specifications Group 3: Base-Case School Model egrid Calculation Population Growth Rate Estimated No. of This Type of School Group 4: Built After 2010 School Model Assumptions ASHRAE Specifications Group 4: Base-Case School Model Four School Groups by the construction year Total sq. ft. for Each Base-case School in Each Climate Zone Compliant with the corresponding ASHRAE 90.1 Total Statewide Energy and Emissions Savings Energy Savings in This County Group Energy Savings for Each Base-case School Individual Energy Efficiency Measures Energy and Cost Savings of each EEM Payback Calculation Cost-Effective EEM

6 Methodology Simplified Approach Grouped counties by ASHRAE /2007 Climate Zones 6 Representative County for Each Climate Zone - Harris County for Climate Zone 2 - Dallas County for Climate Zone 3 - Potter County for Climate Zone 4 Harris (Houston TMY 2)

7 Methodology Development of Base-Case Model (1/2) Sources - ASHRAE Standard , 1999, 2004, and U.S. EPA Energy Star labeled schools in Texas (2010) - Texas Education Agency K-12 schools database (2010) - EnergyPlus Benchmark school models (2010) - NREL s technical support document of the Advanced Energy Design Guide (AEDG) for K-12 schools (2007) 7 Floor area - U.S. EPA Energy Star labeled schools in Texas (2010) - Texas Education Agency K-12 schools database (2010) Texas Education Agency (TEA) No. of Schools No. of Student Avg. No. of Student/school No. of Schools No. of Student Energy Star Total Floor Area (sq.ft.) Avg. sq.ft. per student Estimated Avg. sq.ft./school Elementary 3,919 2,169, ,969 8,578, ,173 Middle 1,613 1,002, ,105 4,473, ,395 High 1,226 1,214, ,708 4,711, ,894 Total 8,276 4,710, ,202 19,059,308

8 Methodology 8 Development of Base-Case Model (2/2) Window-to-wall (WWR) ratio - Field survey of elementary schools in Bryan/College Station school district Bryan College Station School 1 School 2 School 3 School 4 School 5 School 6 Year Built Total Window Area (sq.ft.) 2,352 1,453 2,594 2,929 3,443 2,065 Total Wall Area (sq.ft.) 17,942 19,724 22,541 22,403 30,979 32,517 WWR (%) 13.1% 7.4% 11.5% 13.1% 11.1% 6.4% Average: 10% WWR Schedules (occupancy/lighting/equipment/dhw/heating & cooling set-points) and HVAC/DHW system type - EnergyPlus Benchmark primary school model (2010) - NREL s technical support document (2007) of the AEDG for K-12 Building envelope construction and HVAC/DHW system efficiency and control - ASHRAE Standard , 1999, 2004, and

9 Methodology Development of Energy Efficiency Measures Sources - ASHRAE s AEDG for K-12 Schools (2008) - Collaborative for High Performance Schools (CHPS) Best Practices Manual (2006) - U.S. EPA Energy Star Building Upgrade Manual (2008) 9 Interview with a Maintenance Manager of College Station school district

10 Base-Case School Model (1/4) 10 Building Envelope Common characteristics - 1 story, 79,430 ft 2-10% WWR - Steel framed with 4 studs at 16 o.c. - Concrete slab-on-grade floor - Flat built-up roofing Climate-specific characteristics according to the corresponding requirements of the ASHRAE , 1999, 2004, and ASHRAE Wall R-value: R-13 Roof R-value: R-15 c.i. Glazing U-value: 1.22 Btu/hr ºF ft 2 (CZ 2&3) 0.57 Btu/hr ºF ft 2 (CZ 4) Glazing SHGC: 0.25 SHGC (CZ 2) 0.39 SHGC (CZ 3&4) Classroom Admin Cafe Gym N

11 Base-Case School Model (2/4) 11 Space Conditions Common characteristics - Heating: 70 ºF (60.8 ºF setback) - Cooling: 77 ºF (87.8 ºF setup) - EPD: 1.06 W/ft 2 Code-specific characteristics - LPD: 1.57 W/ft 2 (1989) 1.50 W/ft 2 (1999) 1.20 W/ft 2 (2004 & 2007) Classroom Admin Cafe Gym N

12 Base-Case School Model (3/4) 12 HVAC System Characteristics Common characteristics - 30 ton PVAVS for Classrooms - 10 ton PSZ for Admin/Café/Gym - 80% eff. gas boilers and furnaces - Supply air flow Classroom: 1.00 cfm/ft 2 Admin: 1.03 cfm/ft 2 Café: 1.69 cfm/ft 2 Gym: 1.72 cfm/ft 2 - Ventilation: 15% of design flow Code-specific characteristics - PVAVS: 8.5 EER & 1.7 hp/1,000 cfm (1989) 9.5 EER & 1.7 hp/1,000 cfm (1999) 9.3 EER & 1.7 hp/1,000 cfm (2004) 9.8 EER & 1.5 hp/1,000 cfm (2007) - PSZ: 8.9 EER & 1.2 hp/1,000 cfm (1989) 10.3 EER & 1.2 hp/1,000 cfm (1999) 10.1 EER & 1.2 hp/1,000 cfm (2004) 11.0 EER & 1.1 hp/1,000 cfm (2007) Classroom Admin Cafe Gym N

13 Base-Case School Model (4/4) 13 DHW System Characteristics Common characteristics - Two 125 gallon & 199,000 Btu/hr gas storage water heaters - DHW daily consumption: 0.8 gal/student/day Code-specific characteristics - DHW heater eff.: 77% (1989) 80% (1999, 2004, and 2007) Classroom Admin Cafe Gym N

14 EEM # Base Case Input Individual EEM Energy Efficiency Measures Envelope Measures CZ 2 (Harris County) CZ 3 (Dallas County) CZ 4 (Potter County) EEM Input 1 Increased Roof Insulation R-14 R-15 R-20 R-16 R-15 R-20 R-16 R-15 R-20 R Decreased Glazing U-Value U-1.15 U-1.22 U-0.75 U-1.15 U-1.22 U-0.57 U-0.65 U-0.81 U-0.57 U-0.57 U-0.40 U Decreased Infiltration Classroom: cfm/ft 2 ; Admin cfm/ft 2 ; Café: cfm/ft 2 ; Gym: 0.07 cfm/ft 2 40% Reduction Lighting Measures 4 Decreased LPD (W/ft 2 ) W/ft 2 5 Occupancy Sensor No Occupancy Sensor Occupancy Sensor 6 Daylight Dimming Controls No Daylight Dimming Controls Continuous Dimming Controls 7 Skylights 0% SRR 4% SRR for Gym and Café HVAC System Measures 8 OA Demand Control 15% of design flow Improved AC Efficiency (PVAVS and PSZ EER) Improved Heating System Efficiency Decreased Supply Fan Power Consumption PVAVS with VFD for Fan Control PVAVS with Variable Speed for HW Pump DHW Measures 14 Improved DHW Heater Efficiency Energy 18 Ground Efficiency/Renewable Source Heat Pump Energy (EERE) Projects in Texas No Public GSHP Schools PVAVS:1.7 hp/1000 cfm PSZ 1.2 hp/1000 cfm PVAVS:1.7 hp/1000 cfm PSZ 1.2 hp/1000 cfm Class/Admin: 15 cfm/person Café/Gym: 20 cfm/person PVAVS:10.6 EER PSZ:12.2 EER 80% 90% Inlet Vanes Constant PVAVS:1.7 hp/1000 cfm PSZ 1.2 hp/1000 cfm PVAVS:1.3 hp/1000 cfm PSZ 1.0 hp/1000 cfm VFD Variable 77% 80% 77% 80% 77% 80% 95% 15 Tankless Water Heater DHW SL: 2% & DHW pump electric power: W/Btuh Renewable Measures DHW SL: 0.3% Pump elec. power: 0 W/Btuh 16 Solar PV No PV 200 kw PV (20% of Roof Area) 17 Solar DHW No SDHW equest 3.6 Simulation Software PV-F Chart & F-Chart equest 3.6 Simulation Software Two SDHW (One unit: 128 sq.ft., 120 gal ) 17th Symposium for Improving Vertical GSHP Building Conditions in Hot (120 and Boreholes, Humid Climates 240 depth)

15 Results 1. Base-Case Energy Use for Different School Groups in Each Climate Zone Savings from Individual EEMs 3. ASHRAE AEDG for K-12 Schools

16 Results 1. Base-Case Energy Use for Different School Groups in Each Climate Zone High lighting & equipment energy consumption for all counties High heating consumption for Potter County 16

17 EEM # Individual EEM Results Envelope Measures 2. Savings from Individual EEMs 1 AEDG 23.8% 20.2% 17.4% 13.7% 25.0% 21.5% 16.7% 14.9% 23.9% 24.6% 23.9% 19.4% 2 ASHRAE % 7.6% 4.2% % 7.5% 2.0% Conditions - 5.8% in Hot and 6.3% Humid 5.6% Climates - Annual Total Savings Above Base Case (%) Harris County (Climate Zone 2) Dallas County (Climate Zone 3) Potter County (Climate Zone 4) Increased Roof Insulation 0.5% 0.9% 1.0% 0.4% 1.0% 1.2% 1.4% 0.6% 2.4% 2.8% 2.8% 1.2% 2 Decreased Glazing U-Value 1.4% 2.4% 2.9% 0.9% 2.2% 2.5% 0.5% 1.0% 3.3% 1.2% 1.2% - 3 Decreased Infiltration 1.6% 1.8% 2.1% 2.0% 2.3% 2.4% 2.7% 2.8% 5.6% 5.8% 6.1% 6.4% Lighting Measures 4 Decreased LPD 7.1% 5.4% 1.3% 1.3% 6.1% 5.0% 1.3% 1.2% 2.3% 1.4% 0.3% 0.3% 5 Occupancy Sensor for Lighting Control 1.7% 1.5% 1.1% 1.1% 1.4% 1.3% 1.1% 1.0% 0.6% 0.4% 0.2% 0.2% 6 Daylight Dimming Controls 9.6% 6.6% 4.9% 5.0% 11.2% 6.0% 3.9% 3.5% 3.5% 2.5% 1.4% 1.6% 7 Skylights 1.9% 1.9% 1.4% 1.6% 1.6% 1.1% 0.8% 0.9% -0.8% -0.9% -1.3% -1.2% HVAC System Measures 8 OA Demand Control 4.5% 4.6% 5.1% 4.8% 4.7% 4.4% 4.7% 4.7% 8.5% 9.2% 9.9% 9.6% 9 Improved AC Efficiency 6.8% 3.0% 3.6% 3.2% 6.0% 2.6% 3.2% 2.7% 3.5% 1.4% 1.6% 1.5% 10 Improved Heating System Efficiency 0.8% 1.0% 1.3% 1.1% 1.1% 1.3% 1.4% 1.5% 2.4% 2.9% 3.3% 3.1% 11 Decreased Supply Fan Power Consumption 3.5% 3.6% 3.7% 1.9% 3.5% 3.6% 3.8% 1.9% 3.3% 3.3% 3.4% 1.8% 12 PVAVS with VFD for Fan Control 5.6% 5.6% 5.8% 5.3% 5.4% 5.5% 5.8% 5.2% 4.5% 4.3% 4.3% 3.9% 13 PVAVS with Variable Speed for HW Pump 2.4% 2.4% 2.6% 2.5% 2.1% 2.2% 2.3% 2.3% 2.8% 2.7% 2.8% 2.9% DHW Measures 14 Improved DHW Heater Efficiency 0.7% 0.6% 0.6% 0.6% 0.7% 0.6% 0.6% 0.6% 0.7% 0.5% 0.5% 0.6% 15 Tankless Water Heater 1.1% 1.1% 1.1% 1.2% 1.1% 1.1% 1.2% 1.2% 1.0% 1.0% 1.0% 1.0% Renewable Measures 16 Solar PV 17.9% 18.8% 19.5% 20.4% 20.1% 21.0% 22.3% 22.8% 20.1% 20.0% 20.1% 21.3% 17 Solar DHW 2.4% 2.4% 2.5% 2.6% 2.7% 2.7% 2.8% 2.9% 2.7% 2.6% 2.6% 2.7% 18 Ground Source Heat Pump 6.4% 7.6% 11.2% 10.0% 10.5% 11.2% 12.6% 14.2% 21.0% 24.2% 28.3% 26.9% Combinations zzzzzzzzz Higher saving potential for older school groups zzzzzzzzz Higher saving potential for older school groups Less than 2% savings due to small DHW end-use consumption, but higher savings are expected for the K-5 to K-12 Schools. z Higher savings for Potter County Heating penalty for Potter County Higher savings for Potter County Good Saving Potential Higher savings for Potter County 17

18 Results ASHRAE AEDG for K-12 Schools Simulation Input EEM # Individual EEM AEDG Climate Zone 2 Climate Zone 3 Climate Zone 4 1 Increased Roof Insulation R-25 2 Decreased Glazing U-Value U-0.45 U Decreased Lighting Power Density 1.1 W/ft W/ft 2 5 Occupancy Sensor for Lighting Control Occupancy Sensor 6 Daylight Dimming Controls Daylight Dimming Controls 8 OA Demand Control Classroom/Admin: 15 cfm/person; Café/Gym: 20 cfm/person 9 Improved AC Efficiency PVAVS: 10.6 EER; PSZ 11.3 EER 10 Improved Heating System Efficiency 80% 85% 85% 11 Decreased Supply Fan Power Consumption PVAVS:1.3 hp/1000 cfm; PSZ 1.0 hp/1000 cfm 14 Improved DHW Heater Efficiency 90% - Exterior Wall Insulation Not Required R-3.8 c.i. R-7.5 c.i. - Window Shading 0.5 projection factor (2.5 ft) for East, West, and South - High Albedo Roof Glazing SEER

19 Results 3. ASHRAE AEDG for K-12 Schools Simulation Results 20.2 % for 1999 Base Case (13.7% to 23.8% for Harris County) % for 1999 Base Case (14.9% to 25.0% for Dallas County) 24.6% for 1999 Base Case (19.4% to 24.6% for Potter County) AEDG could be improved with renewable energy options.

20 Summary (1/2) Energy Efficiency/Renewable Energy (EERE) Projects in Texas Public Schools Preliminary results from an analysis of the energy saving potential in new and existing Texas ISDs K-12 simulation model based on the DOE-2.1e program that uses ASHRAE Standard 90.1 code-compliant, 79,430 sq.ft., school buildings for three climate zones in Texas Four base cases (ASHRAE Standard , 1999, 2004, and 2007) for each climate zone Eighteen energy efficient measures 20

21 Summary (2/2) Best Individual EEMs Renewable energy options (Solar PV and GSHP): Largest savings Lighting measures (daylight dimming controls and decreased lighting power density): High savings except Potter County due to the increased heating penalty OA demand control and PVAVS with VFD: Good potential Improved AC efficiency and decreased fan power consumption: high savings for older school groups (1989 base case) 21 ASHRAE AEDG 20.2% to 24.6% of a combined savings above 1999 base case (schools that built between 2000 and 2007) AEDG could be improved with renewable energy options.

22 Future Work & Acknowledgement Future Work Estimation of the total state-wide energy and emissions (NOx, SO 2, and CO 2 ) savings potential Cost and payback analysis 22 Acknowledgement Funding for this study was provided by the U.S. EPA through the Laboratory s Center for Excellence on Displaced Emission Reduction (CEDER) and by the Texas State Legislature through the Texas Emissions Reduction Program (TERP).

23 ENERGY EFFICIENCY/RENEWABLE ENERGY (EERE) PROJECTS IN TEXAS PUBLIC SCHOOLS Thank You!