1. 2014 0 October 2014 Rod Rabold Vice President, SERBCA Board of Directors SERBCA TECH TALK BAS Control Strategies for Energy Savings in Buildings SOUTHEAST CHAPTER

2. 2014 1 Energy Conservation Measures with the Largest Impact at UNC AHU - Discharge Air Temperature (DAT) reset strategy AHU - Proper Economizer and Heat Recovery system operations AHU - Preventing simultaneous heating and cooling VAV - Terminal zone minimum cfm air flow setpoints

3. 2014 2 UNC BAS Control Standards Provided to Designers

4. 2014 3 AHU Required Sensors

5. 2014 4 AHU Required Sequence Logic

6. 2014 5 Preheat Valve Logic

7. 2014 6 CHW Valve Logic

8. 2014 7 DAT Setpoint Reset Logic Cooling Requests and Return Humidity Using Low Select to calculate DAT Setpoint

9. 2014 8 DAT Setpoint Reset Logic Cooling Requests and Return Humidity Using Cascade to calculate DAT Setpoint

10. 2014 9 DAT Reset Using Terminal Load Terminals must be calibrated and working properly to ensure correct cooling call request are being generated. Reset values are adjustable from the front end so each building can be fine tuned. If terminals are not providing accurate cooling call requests then consider return air temperature to reset the AHU

11. 2014 10 DAT Setpoint Reset Logic Return Air and Return Humidity using low select

12. 2014 11 DAT Setpoint Reset Logic Return Air and Return Humidity using cascade

13. 2014 12 DAT Reset Using Return Temperature Using return air temperature produces the best performance if zone temperature adjustment is limited and heating and cooling setpoints (with dead bands) are uniformly set.

14. 2014 13 Terminal Zone Temp Setpoint Heating and cooling dead bands and limited adjustment

15. 2014 14 Graphic Reset Information

16. 2014 15 Summary DAT Strategy AHU discharge air resets can provide significant energy savings. If terminals are calibrated and performing a cooling request logic can be used. If terminals are poorly performing use return air temperature for reset. Reset parameters must be monitored and adjusted per each building. The resets need to be displayed on the graphic so they are easily understood by the staff.