A device that extracts heat from beneath the Earth is called a Geothermal Heat Pump (GHP). The GHP functions based on the principle that heat will move from higher to lower temperature materials, by either conduction or convention (air currents). These pumps absorb energy from both the ground and bodies of water and uses it to provide space and water heating. This is able to occur because the Earth absorbs 50% of the suns heat that reaches the Earth's service.

Ground source heating and cooling provides high-comfort and cost-effectiveness with an environmentally friendly technology that makes use of the Earth's capacity to store energy in the form of heat. Geothermal Heating Systems move heat from the earth or water into a building, or from a building back into the earth. A small amount of electricity is used to operate pumps, fans, controls, and small compressor.

The temperature of the ground a few feet below the surface is relatively constant, to GHPS use it as a source of heating a cooling. GHPs can be used for either retrofit or brand new homes, and they can also provide hot water with no extra cost, just by moving heat around instead of creating it. GHPs are new, but they can save you a lot of money.

Although the initial cost of a new geothermal system is generally more expensive than a traditional heating and cooling system, the extra investment is returned within five to ten years. The ground loop piping is estimated to last over fifty years, and even the internal parts have about a 25 year life span. Every year about 50,000 new geothermal heating systems are added in the United States. They're very reasonable for most areas and can use the Earth for heating when temperatures drop and as a heat sink when it's hot outside.

Quite a number of new residential systems come with desuperheaters, by which excess heat is transferred to the home's hot water storage tank from the geothermal heat pump's compressor, providing a highly efficient means of heating water. But in the spring and autumn, during which the geothermal heat pump system does not operate, the desuperheater will not provide hot water. However, because of the geothermal system's significant advantage in efficiency compared to other water heating methods, 'full demand' systems using a separate heat exchanger to meet hot water needs cost-effectively are now being offered by some manufacturers.