Ground source heat pumps work in much the same way as air source heat pumps, but instead taking energy from the air, they take solar energy which is stored naturally in the ground throughout the year. This energy is used to increase the temperature in your home. The heat pump uses pipe which is filled with a range of liquids to absorb the ground heat and transfer it indoors. This ground temperature heats up a refrigerant to the point that is boils and turns into gas, thanks to its extremely low boiling temperature. Once boiled, the refrigerant is pushed through a compressor, which heats it further to temperatures of around 60-70degrees. This is then used to heat things like your hot water and radiators and underfloor heating. Whilst this process does require some input of power, you can typically expect to get 4 units of energy out, for every unit you put in. Because of this cost effective ratio, ground source heat pumps remain one of the most efficient forms of renewable energy in the UK, especially when combined with solar PV.