Modern ground source heat pump systems are very efficient. For each kilowatt of electricity used to run the heat pump, three to four kilowatts of heat can be delivered to the building. The efficiency of a GSHP installation is very dependent on the quality of the design and installation. The efficiency of the installation is improved by utilising solar recharge of the ground.

The Coefficient of Performance (“CoP”) of a heat pump system depends on the design and quality of the installation: from as low as 2 for an air source heat pump system in unfavourable conditions, up to 4 for an unassisted ground source heat pump, and up to 8 for a well designed ground source heat pump system benefitting from solar recharge of the ground.