Ground-Source Heat Pumps: Tapping the Earth's Mass

Ground-source heat pumps take advantage of stable temperatures just below the Earth's crust for energy-efficient heating and cooling.

Ground-source heat pumps (GSHPs), often called “geothermal heat pumps,” exploit the relatively stable temperatures found just 5 feet (1.5 m) or more below the surface, either depositing or extracting low-intensity heat. Heat pumps—whether ground-source or air-source—are basically air conditioners that can be run in reverse to provide heating as well as cooling.

Air conditioners (and refrigerators) make a relatively cool place cooler by extracting heat from it and releasing the heat in a warmer place. The key to this magic is the refrigerant, a fluid that changes from a liquid to a gas at ambient temperatures. After absorbing heat, the gas moves through a mechanical compressor that squeezes the heat back out, not unlike squeezing water out of a sponge. By releasing this heat to the temperate earth rather than into hot outdoor air, GSHPs cool more efficiently than air conditioners or air-source heat pumps. They provide heat by using the same principle in reverse—drawing heat from the relatively warm earth rather than from cold outdoor air.

Published August 30, 2007

Malin, N. (2007, August 30). Ground-Source Heat Pumps: Tapping the Earth's Mass. Retrieved from