energy efficiency/renewable energy (eere) projects in texas public schools

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

17th Symposium for Improving Building Conditions in Hot and Humid ClimatesAustin TX August 24 – 25, 2010

Jeff S. Haberl, Ph.D., P.EZi Liu, Ph.D.

Hyojin KimJaya Mukhopadhyay

Sunglok DoBahman Yazdani, P.E.

Charles Culp, Ph.D., P.E.Juan-Carlos Baltazar, Ph.D

Energy Systems LaboratoryTexas A&M University

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Energy Efficiency/Renewable Energy (EERE) Projects in Texas Public Schools17th Symposium for Improving Building Conditions in Hot and Humid Climates

2

Outline

Introduction

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)

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)- 20.1% 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 cost-effective energy efficiency and renewable energy projects applied to new and existing Texas Independent School Districts (ISDs)

Process- Preliminary results from an analysis of the energy saving potential in new and

existing Texas Independent School Districts (ISDs)


5

Methodology

Grouped Counties by ASHRAE 90.1-

2004/2007 Climate Zones

Grouped Counties by ASHRAE 90.1-


Elementary SchoolElementary School

Middle SchoolMiddle School

High SchoolHigh School

Avg. No. of Students/This Type of School

Avg. No. of Students/This Type of School

Energy Star School

Energy Star School

Texas Education

Agency

Texas Education

Agency

Group 1: Built Before

2000

Group 1: Built Before

2000

SECO K-12 Energy Audit

SECO K-12 Energy Audit

No. of This Type of School

No. of This Type of School

Avg. Sq. ft. /Student

Avg. Sq. ft. /Student

Avg. Sq. ft./This Type of SchoolAvg. Sq. ft./This Type of School

Year This Type of School Built

Year This Type of School Built

Group 2: Built 2000 -

2007

Group 2: Built 2000 -

2007

Group 3: Built 2007-

2010

Group 3: Built 2007-

2010

Total sq. ft. for Each Base-case School in Each Climate Zone

Estimated No. of This Type of

School

Estimated No. of This Type of

School

Population Growth RatePopulation

Growth Rate

Group 4: Built After

2010

Group 4: Built After

2010

School Model AssumptionsSchool Model Assumptions

Group 1: Base-Case School Model

ASHRAE 90.1 1989 Specifications














Weather ZoneWeather Zone

Assigned Weather Station

Assigned Weather Station

EPlus Benchmark School Model

EPlus Benchmark School Model

Survey of College Station/Bryan ISDsSurvey of College

Station/Bryan ISDs

AEDG School Baseline Model

AEDG School Baseline Model

School Compliant with ASHRAE AEDGSchool Compliant

with ASHRAE AEDG

Individual Energy Efficiency Measures

Individual Energy Efficiency Measures

SimulationSavings/sq. ft.

Energy and Cost Savings of each

EEM

Payback Calculation Cost-Effective EEMCost-Effective EEM

Energy Savings for Each Base-case School

Energy Savings for Each Base-case School

Energy Savings in This County Group

Energy Savings in This County Group

Total Statewide Energy and Emissions SavingsTotal Statewide Energy and Emissions Savings

Calculation

eGrid

Four School Groups by the construction year

Compliant with the corresponding ASHRAE 90.1


6

Methodology

Simplified Approach Grouped counties by ASHRAE 90.1-


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)


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Methodology

Development of Base-Case Model (1/2)Sources

- ASHRAE Standard 90.1-1989, 1999, 2004, and 2007- 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)

Floor area- U.S. EPA Energy Star labeled schools in Texas (2010)- Texas Education Agency K-12 schools database (2010)

Texas Education Agency (TEA) Energy StarEstimated Avg.

sq.ft./schoolNo. of Schools

No. of Student

Avg. No. of Student/school

No. of Schools

No. of Student

Total Floor Area (sq.ft.)

Avg. sq.ft. per student

Elementary 3,919 2,169,097 553 105 59,969 8,578,253 143 79,173

Middle 1,613 1,002,912 622 31 24,105 4,473,684 186 115,395

High 1,226 1,214,495 991 15 24,708 4,711,418 191 188,894

Total 8,276 4,710,935 160 110,202 19,059,308


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Methodology

Development of Base-Case Model (2/2)Window-to-wall (WWR) ratio

- Field survey of elementary schools in Bryan/College Station school district

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 90.1-1989, 1999, 2004, and 2007

-

Bryan College Station

School 1 School 2 School 3 School 4 School 5 School 6

Year Built 2009 1999 1990 1996 1999 2007

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


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)

Interview with a Maintenance Manager of College Station school district


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Base-Case School Model (1/4)

Building Envelope Common characteristics

- 1 story, 79,430 ft2 - 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 90.1-1989, 1999, 2004, and 2007

- ASHRAE 90.1-1999 Wall R-value: R-13 Roof R-value: R-15 c.i. Glazing U-value: 1.22 Btu/hr ºF ft2 (CZ 2&3) 0.57 Btu/hr ºF ft2 (CZ 4) Glazing SHGC: 0.25 SHGC (CZ 2) 0.39 SHGC (CZ 3&4)

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Classroom

Admin

Cafe

Gym


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Space Conditions Common characteristics

- Heating: 70 ºF (60.8 ºF setback)- Cooling: 77 ºF (87.8 ºF setup)- EPD: 1.06 W/ft2

Code-specific characteristics- LPD: 1.57 W/ft2 (1989) 1.50 W/ft2 (1999) 1.20 W/ft2 (2004 & 2007)

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Classroom

Admin

Cafe

Gym


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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/ft2

Admin: 1.03 cfm/ft2

Café: 1.69 cfm/ft2

Gym: 1.72 cfm/ft2

- 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)

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Classroom

Admin

Cafe

Gym


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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)

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Classroom

Admin

Cafe

Gym


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Energy Efficiency MeasuresEEM

#Individual EEM

Base Case Input

EEM InputCZ 2 (Harris County) CZ 3 (Dallas County) CZ 4 (Potter County)

1989 1999 2004 2007 1989 1999 2004 2007 1989 1999 2004 2007

Envelope Measures

1 Increased Roof Insulation R-14 R-15 R-20 R-16 R-15 R-20 R-16 R-15 R-20 R-25

2 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-0.45

3 Decreased Infiltration Classroom: 0.085 cfm/ft2; Admin 0.083 cfm/ft2; Café: 0.087 cfm/ft2; Gym: 0.07 cfm/ft2 40% Reduction

Lighting Measures

4 Decreased LPD (W/ft2) 1.57 1.5 1.2 1.57 1.5 1.2 1.57 1.5 1.2 1.1 W/ft2

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 flowClass/Admin: 15 cfm/person

Café/Gym: 20 cfm/person

9 Improved AC Efficiency (PVAVS and PSZ EER)

8.58.9

9.510.3

9.310.1

9.811.0

8.58.9

9.510.3

9.310.1

9.811.0

8.58.9

9.510.3

9.310.1

9.811.0

PVAVS:10.6 EERPSZ:12.2 EER

10 Improved Heating System Efficiency

80% 90%

11 Decreased Supply Fan Power Consumption

PVAVS:1.7 hp/1000 cfmPSZ 1.2 hp/1000 cfm

1.51.1


1.51.1


1.51.1


12 PVAVS with VFD for Fan Control

Inlet Vanes VFD

13 PVAVS with Variable Speed for HW Pump

Constant Variable

DHW Measures

14 Improved DHW Heater Efficiency

77% 80% 77% 80% 77% 80% 95%

15 Tankless Water Heater DHW SL: 2% & DHW pump electric power: 0.00381 W/BtuhDHW SL: 0.3%

Pump elec. power: 0 W/Btuh

Renewable Measures

16 Solar PV No PV 200 kW PV (20% of Roof Area)

17 Solar DHW No SDHWTwo SDHW

(One unit: 128 sq.ft., 120 gal )

18 Ground Source Heat Pump No GSHPVertical GSHP

(120 Boreholes, 240 depth)

eQuest 3.6 Simulation Software

eQuest 3.6 Simulation Software

PV-F Chart & F-Chart


15

Results

1. Base-Case Energy Use for Different School Groups in Each Climate Zone

2. Savings from Individual EEMs

3. ASHRAE AEDG for K-12 Schools


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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


2. Savings from Individual EEMs

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ResultsEEM #

Individual EEM

Annual Total Savings Above Base Case (%)

Harris County (Climate Zone 2) Dallas County (Climate Zone 3) Potter County (Climate Zone 4)

1989 1999 2004 2007 1989 1999 2004 2007 1989 1999 2004 2007

Envelope Measures

1 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

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 90.1 2007 11.9% 7.6% 4.2% - 11.7% 7.5% 2.0% - 5.8% 6.3% 5.6% -

zzzzzzzzz

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Higher savingsfor Potter County

Heating penaltyfor Potter County

Higher saving potential for older school groups

Higher savings for Potter County

Higher saving potential for older school groups

Higher savingsfor Potter County

Less than 2% savings due to small DHW end-use consumption, buthigher savings are expected for

the K-5 to K-12 Schools.

Good Saving Potential


18

Results

3. ASHRAE AEDG for K-12 Schools Simulation Input

EEM #

Individual EEMAEDG

Climate Zone 2 Climate Zone 3 Climate Zone 4

1 Increased Roof Insulation R-25

2 Decreased Glazing U-Value U-0.45 U-0.42

4 Decreased Lighting Power Density 1.1 W/ft2 0.9 W/ft2

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 0.3 0.3 0.7

- Glazing SEER 0.25 0.25 0.40


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)

21.5% 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 90.1-1989, 1999, 2004, and 2007) for each climate zone

Eighteen energy efficient measures


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)

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, SO2, and

CO2) savings potential Cost and payback analysis

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).

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

Thank You!

energy efficiency/renewable energy (eere) projects in texas public schools

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