Ground source heat pump installations have very low running costs because they exploit the fundamental characteristic of the ground to act as an efficient store of thermal energy. In very cold weather, when heating is most needed, a ground source heat pump has access to warmer temperatures from the ground than an air source heat pump has from ambient air.

The Thermal Energy Storage capacity of the ground allows GSHPs to be used efficiently at all hours of day and night – this provides the opportunity to use GSHPs at night when electricity is cheaper.