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Athens Nighttime Setback

photo: Science and Ecosystem Support Division (SESD) Laboratory

Background

The nighttime setback at EPA’s Science and Ecosystems Support Division’s (SESD) Laboratory in Athens, Georgia, originated with the facility’s Environmental Management System (EMS) Team. After brainstorming different energy conservation measures, the EMS team determined that the facility heating, ventilation, and air conditioning (HVAC) system was the facility’s largest user of energy because it ran 24 hours a day, seven days a week. This resulted in considerable waste of energy because the facility was not occupied the entire time. The EMS Coordinator led the team in implementing a nighttime setback to the air handling units (AHUs) to reduce the amount of energy the HVAC system consumed.

Reprogramming

EPA, along with the owner of the facility, contracted with a mechanical and engineering firm to reprogram the facility’s Building Automation System (BAS).  After being reprogrammed, the HVAC system automatically ceases in offices, cubicle areas, and common areas after 7:30 p.m., and resumes automatically at 5:30 a.m.  However, built-in safeguards allow the system to automatically return to normal levels if the humidity or temperature rises above a prescribed set point.

Flexibility

The facility has three switches to bypass the setback, which allows for flexibility. To govern the use of these switches, the Athens EMS team wrote an energy policy for all employees. For instance, if employees wish to work on the weekend, when the system would normally be shut down, they may submit an application per the energy policy, and the appropriate personnel will approve the bypass.

The nighttime setback affects offices, common areas, and hallways.  Laboratories were not included because of the specialized equipment they contain.

Energy Savings

The setback helped the facility achieve an energy savings of 7.8 percent in FY 2008 compared to an FY 2007 baseline.

The line chart below compares month-to-month electricity use at Athens SESD in FY 2007, FY 2008, and FY 2009.

Line chart comparing the electricity use of Athens SESD in FYs 2007, 2008, and early 2009.  Click for text.

Date: March 3, 2009

The setback also reduced the load on the facility’s chillers, which saves cooling tower make-up water.


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