An authoritative study for ASHRAE proves geo heat pumps ARE best

CaliforniaGeo 6-20-17

[This study was conducted by Oklahoma State University’s Jeffrey Spitler and Laura Southard.  Data processing was overseen by Xiaobing Liu of Oak Ridge National Laboratory.]

A major retrofit project to the U.S. headquarters building in Atlanta, GA for the American Society of Heating and Refrigeration Engineers was envisioned as a “split system” but not in the usual sense—the building’s two floors were handled by different kinds of systems and the results were compared over a year’s time.

Air-sourced VRF (variable refrigerant flow) heat pumps served the first floor of the building while two-speed geo heat pumps backed by (12) 400-foot boreholes with single U-bend loops served the second floor.  Copious instrumentation measured every nook and cranny of both systems and their operating parameters were stored and analyzed.

The geo heat pumps consumed 44% less electricity than the air-sourced VRFs, and they dramatically lowered electrical demand peaks as well.  This is not surprising, since air-sourced equipment seeks to heat when it’s coldest outside and to cool when it’s hottest.  That’s the time most challenging for the equipment.  Geo heat pump equipment is not subject to daily swings due to outdoor temperature because its thermal connection to reject and absorb heat is to a stable closed loop ground heat exchanger where the earth remains at a constant temperature.  The closed loop ground heat exchanger takes the place of the exposed condenser units exposed to the outside air required for the VRF equipment.

Greater coverage of this project from a technical, performance and engineering perspective is available on our website at this LINK.