Hybrid heating systems use a smart thermostat, air source heat pump (ASHP) and furnace to cost effectively heat and cool your building with low greenhouse gas emissions across a wide range of temperatures. The ASHP moves heat and replaces the air conditioner (AC) in a typical setup to provide both cooling and heating compared to an AC unit that only cools. When outside air temperatures exceed the capabilities of the heat pump, the smart thermostat engages an auxiliary furnace powered with electricity, biofuels or fossil fuels to create heat. The smart thermostat can also optimize efficiency by using less energy use when the building is unoccupied and when residents are asleep. With this kind of system, fossil fuel heating can be eliminated or greatly limited to only the coldest weeks of the year, especially with the newest generation cold climate air source heat pumps.
Alternatively, geothermal / ground source heat pumps can be used without auxiliary heat created by a furnace.