Heat Pumps.
All air, including cold winter air,contains a certain amount of heat.The refrigerant in a heat pump system absorbs this heat when air passes over the outdoor coil.
This absorption of heat changes the refrigerant from a low temperature liquid to a low temperature, low pressure vapor.
The vapor then passes through a compressor where it is compressed into a high pressure,high temperature vapor.The hot vapor then circulates through the indoor coil.
The fan in the indoor unit draws air over the coil, heating the air and then returning warm filtered air back into the room.
This form of heating can be up to 70% more efficient than other types of heating, therefore reducing carbon emissions.