Geothermal heat pump
A geothermal heat pump uses the earth as either a heat or cooling source. The system takes advantage of the moderate temperatures underground to greatly improve efficiencies of HVAC (heating and cooling) equipment. Gundersen installed a 300-ton heat pump along with 156 wells buried about 400 feet underneath a parking lot. At that depth, the ground is at a relatively constant temperature of roughly 48 degrees, providing an efficient heating and cooling source year-round.