Future Energy Solutions produced a report for DTI and DEFRA (“Renewable Heat and Heat from Combined Power Plants—Study and Analysis”) which assessed the carbon saving potential of various sources of renewable heat, including ground source heat pumps. This study suggests that if ground source heat pumps were installed in all off-gas grid residential properties, carbon savings of around 3.9MtC/year could be achieved. No such assessment has been made of the potential of air source or water source heat pumps.