PNW Smart Grid Demonstration Project

HVAC Load Shed

Smart Grid >> Grid Stability Support >> HVAC Load Shed
WSU Steam PLant

One feature developed by WSU in support of the SGDP goal to investigate the use of regional assets to help stabilize the electrical grid during upset conditions is the Heating, Ventilation, and Air Conditioning (HVAC) Load Shed.

The HVAC Load Shed involves selected non-laboratory, low impact areas such as offices, hallways, conference rooms, classrooms, etc. When Battelle/Avista requests WSU to initiate an HVAC Load Shed, the air flow in the selected rooms will be reduced to near zero for approx. 15 minutes max. While this short reduction should normally have little noticeable effect, there is an over-ride button on the room thermostat which an occupant can trigger to restore normal conditions, should that become necessary. WSU established a number of constraints on requests for the HVAC Load Shed in order to minimize potential impacts, including a separation of at least 3 hours between requests, allowing requests only when outside air temperatures are above 0 deg. and below 95 deg., etc. In addition, WSU always has the option to “opt out” on any request if activating the HVAC Load Shed would be problematic for any reason. However, it is WSU’s intent to activate the HVAC Load Shed as requested whenever possible so the SGDP results will provide a clear determination as to whether this feature is viable tool to apply in other places across the nation to assist with the electric grid stabilization.

The HVAC Load Shed capability will also allow us to reduce significant energy waste that occurs during the low occupancy periods (evenings/weekends) by reducing ventilation levels until such time as the building fan systems shut down per their normal operating schedules. Most buildings have less than 5% occupancy after hours or weekends, but the building fan systems are operated until the buildings are officially closed to support those activities. That means much of the air being heated/cooled and blown around the facility in those time frames serves no purpose – just wasted energy! So on weekends and sometime after 5pm each evening during the week, a Low Occupancy HVAC Load Shed will be triggered, reducing the air flow in the selected rooms until the building fans shut down as scheduled. However, for any occupants that are working, the thermostat over-ride button can be pushed and normal conditions will be restored for 2 hours. At the end of each two hour period, the button can be pushed again to continue the HVAC Load Shed over-ride for another two hours.

Additional information on the HVAC Load Shed feature is available to identify the Buildings/Rooms involved, the Room Thermostat Over-ride feature, and the Building/Room selection process

WSU Benefits
  • The HVAC Load Shed capability applied to both grid stabilization and Low Occupancy energy conservation makes a strong statement regarding WSU support of sustainability goals, reducing energy costs at least $70k annually to free up funding to support the core campus objectives
  • As the electrical power rates continue to increase, the ability to shed HVAC Load on demand for short periods of time is one tool which can be used for peak shaving to reduce power costs
  • The Low Occupancy evening/weeend HVAC Load Shed with Occupant Over-Ride capability will reduce energy costs while maintaining support for the core campus missions
Facilities Services, 100 Dairy Road, Washington State University, Pullman WA 99164-1150, 509-335-9000