Already popular in mainland Europe and gaining more extensive use in the US is geothermal heat pump ( GHP ) technology. The geothermal heat pumps provide heating or cooling for homes and other buildings using natural and renewable heat sources just underneath the Earth’s surface. They can also help to provide hot water.
Whereas residential GHP systems are generally more expensive initially to install than other systems of heating and cooling, their greater efficiency means the cost of investment can be recovered in two to ten years. After that, the energy and the costs of maintenance are much less than conventional systems.
The way it works depends on the time of the year. In winter, a solution of water circulates through a system of buried pipes absorbing heat. A heat pump concentrates the thermal energy and transfers it to the standard air conditioning ductwork in the home. In summer, the process is reversed: the heat is extracted from the house and it is transferred through the heat pump to the buried pipework where the excess heat is dispersed into the ground. The only required external energy is the small amount of electricity to work the pump and fan.