Heat pumps require only a small amount of electricity to harvest, upgrade and move heat from one location to another. To achieve this a vapour compression cycle is used, which has the ability to take low temperature renewable heat from the environment and raise it to usable temperatures capable of handling the space and water heating loads required in buildings.

Heat pumps use a refrigerant as an intermediate fluid to absorb heat where it vaporises, in the evaporator, and to release it where it condenses, in the condenser. If the heat pump is reversible a reversing valve allows for the flow direction of the refrigerant to be changed.