A heat pump is a mechanical system that extracts heat out of a cold space into a warmer one, such as out of the air or the ground and into a home. Heat pumps can also be used for cooling and typical examples of this are air conditioning units and refrigerators. The relative energy and cost savings for installing a heat pump depend on your heating system and the current cost of energy. By running a heat pump you will use less natural gas, but you will use more electricity to run the pump.