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Energy Efficiency Study on Student Recreation Center Gang Wang, Ph.D., P.E. Civil and Architectural Engineering Texas A&M University - Kingsville.

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Presentation on theme: "Energy Efficiency Study on Student Recreation Center Gang Wang, Ph.D., P.E. Civil and Architectural Engineering Texas A&M University - Kingsville."— Presentation transcript:

1 Energy Efficiency Study on Student Recreation Center Gang Wang, Ph.D., P.E. Civil and Architectural Engineering Texas A&M University - Kingsville

2 Outline Background of Energy Conservation Studied Facility Information Purpose Energy Studies –Current control sequences –Energy performance –Improvement –Savings estimation –Troubleshooting Conclusion

3 Building Energy System Mechanical system –Chilled water (chiller) –Heater (electrical/hot water) –Fan and pump (motor) Lighting and power –Lighting –Office equipment –Motor (chiller, fan and pump) and electrical heater

4 Mechanical or HVAC System Remove impacts –People (250Btu/h & 0.2lbmv/h) –Lighting and power system –Climate and solar (envelope) Create indoor environment –Temperature (75F) –Humidity (50%rh): 55F SAT –Indoor air quality: 15CFM (ft 3 /min) OA or Indoor CO2=700PPM + OA CO2 Minimize energy usage –Chilled water (Chiller/electricity.) –Fan and pump (electricity) –Heating (hot water or electricity)

5 Challenges DOE: Buildings consume 40% of U.S. energy –HVAC (32%) –lighting and power (37%) Electricity consumption –4.3% per year increase Natural gas ($/mmBtu): –$3.0 in 2002 to $14 in TAMUK: $4M/yr Improve energy efficiency ASHRAE standard sets an energy savings target of 30%

6 Energy Efficiency Measures Electrical System –Reduce usage –Reduce HVAC load

7 Energy Efficiency Measures Electrical System –Reduce usage –Reduce HVAC load Indoor Comfort and Health –SAT=55F (humidity control) –Maintain required OA intake (Annual $1.75 for 1CFM OA) Partial Load Operation –Reduce fan speed –Avoid simultaneous cooling and heating

8 Studied Facility Information Student Recreation Center, built in 2010 Floor area: 38,000 ft 2 –Gym –Weights –Running track –Offices Occupancy: –Design: 615 persons. –Actual: < 200 persons

9 HVAC System Information Air Handling Unit –AHU1 (SZ) : Gym –AHU2 (MZ) : Track –AHU3 (SZ) : Weights –AHU4 (SD) : Offices –AHU-OA Chilled water Electrical heating Siemens APOGEE. Variable frequency drive (VFD) on AHU fans

10 Purposes Identify energy efficiency measures –Minimize energy consumption –Improve indoor thermal condition –Increase physical plant cooling capacity Develop energy efficiency control Estimate cost savings

11 AHU Schematics

12 Control Sequences by Design Engineer

13 APOGEE PPCL Program by Control Engineer …… 00390C SPEED CONTROL 00410IF("%X%OCC") THEN GOTO SET(50,"%X%SVD") GOTO TABLE(SECND1,"%X%SVD",0,20,60,100) 00430C DISCHARGE TEMPERATURE CONTROL 00450LOOP(0,"B570.A01RMT","%X%LOOP","B570.A01RMSP",1000,100,8,1,50,0,100,0) 00460IF("%X%HUMOVRD".EQ. OFF) THEN TABLE("%X%LOOP","%X%CCV",50,0,100,100) 00470IF("%X%HUMOVRD".EQ. ON) THEN SET(100,"%X%CCV") 00480DBSWIT(1,"%X%LOOP",40,45,"%X%EH1") 00490DBSWIT(1,"%X%LOOP",25,40,"%X%EH2") 00500DBSWIT(1,"%X%LOOP",5,20,"%X%EH3") 00510C DAMPER CONTROL 00530IF("%X%CO2".LT ) THEN GOTO SET(100,"%X%OAD") GOTO LOOP(128,"B570.A02OAF","%X%OALOOP","B570.A02OASP",6,4,1,1,50,0,100,0) 00580TABLE("%X%OALOOP","%X%OAD",0,15,100,100) 00600GOTO 10

14 Summary of Control Sequences OA flow is adjusted based on a design setpoint (615 vs. 200) –OA is fully open if CO2>700ppm Space temperature is controlled by cooling coil or electrical heater –Cooling coil is fully opened if space is humid Supply fan speed: 100% (no control) No supply air temperature control

15 Outside Airflow (OA) Control PerformancePerformance –Low space CO2 –Excessive OA intake AnalysisAnalysis –Design OA flow setpoint, 8,200CFM –Fault space CO2 setting: 700ppm (+OA CO2) –Fault CO2 sensors ImpactImpact –More chilled water –Disturbance on indoor humidity

16 Fan Speed Control Performance:Performance: –Full speed: 24/7 AnalysisAnalysis –No fan speed control ImpactImpact –Waste fan power –Increase cooling load

17 Space Air Temperature Control PerformancePerformance –Space air temperature is maintained

18 Heating and Cooling Performance PerformancePerformance –Cooling coil and heater is hunting AnalysisAnalysis –Single control loop with huge thermal capacity ImpactImpact –Wastes chilled water and electricity

19 Supply Air Temperature Control PerformancePerformance –Fluctuated SAT(55F) –Simultaneous heating and cooling AnalysisAnalysis –No SAT control –Coil thermal capacity ImpactImpact –High space humidity –Waste chilled water and electricity

20 Space Humidity Control

21 Lighting Control PerformancePerformance –Lights are on during unoccupied hours AnalysisAnalysis –Fault schedule ImpactImpact –Waste electricity

22 Improve Control (Lighting) Current Control –On during weekday unoccupied time Improved control –Off during unoccupied time

23 Improve Control (Outside Air) Current Control –Design OA flow setpoint, 8,200CFM –Fault space CO2 control: 700ppm Troubleshoot –Fault CO2 sensors Improved control –OA flow setpoint: 3,000CFM based on actual occupancy –Space CO2: 1000ppm Troubleshoot –Calibrate CO2 sensors

24 Improve Control ( Fan Speed and Temperature) Current Control –No supply air temperature (humidity) control –No fan speed control –Cooling coil and heater directly control space temperature Improved control –Cooling coil is modulated to maintain SAT at 55F –Fan speed is modulated to maintain space temperature. –Heater is stepped on or off to maintain space temperature if airflow drops to min setpoint.

25 Estimated Annual Savings UnitLightingFanHeaterOA ElectricitykWh52,000122,252239,9800 Chilled Water (electricity)kWh13,00037,04672,721136,200 Total savingskWh65,000159,298312,701136,200 Electricity rate$/kWh Cost savings$3,51012,90325,32911,032 Total savings$52,774

26 Troubleshooting (Fault Cooling Coil Valve)

27 Preliminary Results Baseline rate: 96kWBaseline rate: 96kW Valve fault: 164kWValve fault: 164kW –$48,180/yr wasted Repair and preliminary control upgrade:90kWRepair and preliminary control upgrade:90kW Final upgrade: 55kWFinal upgrade: 55kW –$52,774/yr reduced

28 Conclusion Identify energy efficiency measuresIdentify energy efficiency measures –Lighting control –Outside air –Integrate fan speed and cooling coil control –Calibrate CO2 sensor and repair cooling coil valve Annual savings: $52,774Annual savings: $52,774 –Electricity: 414,232kWh or 52% –Chilled water: 2,955MMBtu or 45% No major retrofitsNo major retrofits

29 Questions and Comments? Emmanuel Ayala, Joel Wright, Leah M. Ayala from Department of Civil and Architectural Engineering and Ricardo Contreras Jr. from University Facilities. Project team also includes Emmanuel Ayala, Joel Wright, Leah M. Ayala from Department of Civil and Architectural Engineering and Ricardo Contreras Jr. from University Facilities.


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