SERBCA TECH TALK BAS Control Strategies for Energy
SERBCA TECH TALK BAS Control Strategies for Energy Savings in Buildings SOUTHEAST CHAPTER Rod Rabold Vice President, SERBCA Board of Directors 0 October 2014
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 1 2014
UNC BAS Control Standards Provided to Designers 2 2014
AHU Required Sensors 3 2014
AHU Required Sequence Logic 4 2014
Preheat Valve Logic 5 2014
CHW Valve Logic 6 2014
DAT Setpoint Reset Logic Cooling Requests and Return Humidity Using Low Select to calculate DAT Setpoint 7 2014
DAT Setpoint Reset Logic Cooling Requests and Return Humidity Using Cascade to calculate DAT Setpoint 8 2014
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 9 2014
DAT Setpoint Reset Logic Return Air and Return Humidity using low select 10 2014
DAT Setpoint Reset Logic Return Air and Return Humidity using cascade 11 2014
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. 12 2014
Terminal Zone Temp Setpoint Heating and cooling dead bands and limited adjustment 13 2014
Graphic Reset Information 14 2014
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. 15 2014
- Slides: 16