The temperature of the buildings is maintained year round using the geothermal system eliminating the need for separate heating and cooling appliances. The parts of this system include: closed loops of tubing sunk in wells 45 m deep and filled with glycol (antifreeze), a pump to circulate the glycol through the wells and back to the building, a heat pump similar to one found in a refrigerator, and a forced air system to distribute the warmed or cooled air.
In winter, glycol moves heat from the earth to the buildings. The temperature of the glycol coming into the building is only 8 to 10 C but the heat is boosted to the desired temperature by the heat pump and distributed throughout the buildings using a conventional forced air system. In summer the heat pump is used to move heat from the building to the glycol which is then cooled in the wells and returned to the building - ready to absorb more heat.
Some electricity is required to run the components of the system, but with the main source of energy being free, geothermal heat pumps are a cost-effective and green alternative.
More information on Ground Source Heat Pumps