Geothermal heat pumps operate like air-to-air heat pumps, transferring rather than creating heat; however, they use the ground or water as a heat source and heat sink, rather than outside air. And, because the ground or water temperatures are much more constant year-round (warmer in winter and cooler in summer) geothermal heat pumps operate more efficiently than air-to-air heat pumps.

Geothermal heat pumps are becoming increasingly popular due to their heating and cooling energy efficiency, and related environmental and ownership benefits, especially where groundwater is available or soil conditions are favorable.

In the heating mode, a geothermal heat pump typically extracts two-thirds or more of the needed energy from the earth or water loop and moves it indoors. Only one-third of the energy needed is purchased power, primarily used to run the compressor. In the summer, geothermal heat pumps move heat from indoors into the relatively cool earth or water loop.

Additional ownership benefits include more useable space in the home, since the indoor unit can be installed in a portion of an equipment room or small closet. And, there is no visible outdoor unit to suffer deterioration from weather, vandalism, or compressor noise.

Geothermal heat pumps have lower operating, maintenance, and life-cycle costs, increased reliability, and provide greater comfort than other heating and cooling systems. In the years ahead, as fuel costs rise and environmental factors play more important roles in decision making, we can expect increasing acceptance of this remarkable technology.