Ground Source Heat Pumps

An Introduction

Ground source heat pumps are one of the renewable energy technologies that is eligible for the Domestic Renewable Heat Incentive (RHI).

Ground source heat pumps are low maintenance systems that use pipes buried in your garden to extract heat from the ground. This heat passes through a heat exchanger into the heat pump and is then distributed via a heating system such as radiators or underfloor heating for use in your home. It may also be used for domestic water heating.

Eligible ground source heat pumps can draw heat from either the ground or surface water, or both. Water source heat pumps are eligible and receive the same tariff as ground source heat pumps.

The temperature underground stays fairly constant all year round which means your heat pump can be used even in the middle of winter. It is also a never ending heat source. With the increasingly expensive cost of oil and gas, heating your home with a heat pump offers the chance to benefit directly from all future efficiency gains in the electricity market.

As well as lowering your fuel bills, installing a ground source heat pump can provide you with an income through the RHI.

A typical 10kW installation with an SPF of 4.1 will generate an expected RHI of £2507 a year. You can also expect to save £790 a year on heating bills too.

Heat pumps need electricity to run which is taken into account when calculating the RHI payments. The payment is based on the Seasonal Performance Factor (SPF) for each installation. To be eligible, all heat pumps must have a minimum SPF of 2.5. This is the government’s new recognized measure of the efficiency of a heat pump.

According to the Ground Source Heat Pump Association, for every unit of electricity used by the heat pump, three to four units of heat are captured and transferred. This means a well installed ground source heat pump can be up to 400% efficient in terms of its use of electricity. If the electricity is provided by renewable energy, then carbon emissions can be reduced to zero.


Tap into free environmental energy by harvesting energy from the ground. Probes are put into the ground to a depth of 50-100 metres, depending on the site conditions. A heat transfer medium transports the heat from below ground to the heat pump, where it is ready for you to use in your home.

This most frequently used type of heat pump operates in practical terms with the same efficiency all year round, as the temperature underground is almost constant. A relatively small area is needed for drilling.