Geothermal heat pumps, also known as ground-source heat pumps, are an energy-efficient alternative to furnaces and air conditioners. Geothermal systems move heat rather than make heat. During the winter, solar warmth stored in the ground is moved into the home. During the cooling season, solar warmth collected in the home is moved to the cool earth. Hardware consists only of a heat pump connected to a series of small diameter pipes buried underground. An anti-freeze solution circulating through the pipes carries heat between the ground and the heat pump.
Geothermal offers several advantages:
Ground-source heat pumps, use the constant temperature of the earth as the exchange medium instead of the outside air temperature. This allows the system to reach fairly high efficiencies (200%-400%) on the coldest of winter nights, compared to 175%-250% for air-source heat pumps on cool days.
While many parts of the country experience seasonal temperature extremes—from scorching heat in the summer to sub-zero cold in the winter—a few feet below the earth’s surface the ground remains at a relatively constant temperature. Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer. The geothermal heat pump takes advantage of this by transferring heat stored in the earth or in ground water into a building during the winter, and transferring it out of the building and back into the ground during the summer. The ground, in other words, acts as a heat source in winter and a heat sink in summer.