The refrigerant is compressed outdoors, where it releases heat, and evaporated indoors, where it absorbs heat. The process of moving heat in this manner requires input energy in the form of electricity to drive it.
Electricity is used to both pump the fluid through the cycle and blow the cooled air into the home.
To cool an entire house, several room units are necessary. Central air conditioning systems also operate on the compressor cycle principle and are designed to cool the entire house. The cooled air is distributed throughout the house using air ducts, which may be the same ducts that are used by the heating system. Heat pumps , described in the heating section, use the compressor cycle, but it is reversible. In the summer, the heat pump transfers heat from indoors to outdoors.