In recent years, the term geothermal heating has frequently been used to refer to the heating and cooling that can be achieved through the use of a geothermal heat pump. This technique is generally for residential use. It involves a refrigerant liquid being pumped through pipes in the ground, heating the liquid. This liquid then is brought back into the house, and the heat exchanged. The same technique is used to cool the house.
Geothermal heat pumps take advantage of the natural constant temperature of the earth. During winter when the ground temperature is warmer than the air above it, geothermal heat pumps use the earth’s soil (or groundwater) to recover the earth’s heat. In contrast, an air-source heat pump will remove heat from the cold outside air and thus requires more energy.
In the summer months, geothermal heat pumps deliver heat to the same relatively cool soil (or groundwater) rather than delivering it to the hot outside air. As a result, the heat is pumped over a smaller temperature difference with a geothermal heat pump and this leads to higher efficiency and lower energy use.