How efficient are air source heat pumps?

When properly installed, an air source heat pump can produce up to 5 times more heat energy to the home than the electrical energy it consumes.

The basis of heat pump efficiency is known as ‘Coefficient of Performance’ (or ‘COP’). For example, 3 units of environmental energy plus 1 unit of electricity equals 4 units of heating energy, hence a COP rating of up to 4. This is subject to suitable low flow temperatures and house insulation levels.