A heat pump moves heat energy from one place to another and changes the temperature from lower to higher. An example of a commonly known heat pump is a domestic refrigerator. Where heat pumps are used for heating applications, heat is removed from the source (ambient air, water, soil or bedrock) and then discharged where the heat is needed. Where cooling is required, the reverse happens and heat is removed and discharged into air, water, soil or rock. The most common form of heat pump used within domestic dwellings and are eligible for government funding under the clear-skies programme, are ground source heat pumps

In the UK, the earth that lies a few metres below our feet, keeps a constant temperature of about 11-12C throughout the year. The ground has a high thermal mass which allows it to store heat from the sun during the summer.

Ground Source heat pumps tap the heat within the ground and convert it into energy. The heat pump operates under similar principles to a refrigerator. The heat is captured from within the ground by either pipes laid into trenches or down a borehole and is eventually distributed within the building through radiators or under-floor heating.

Performance details

The performance of Ground Source Heat Pumps is commonly measured by the coefficient of performance (CoP) which is the ratio of units of heat output for each unit of electricity used to power the heat pump. Typical CoPs range from 2.5 to 4, with the higher end of the range being for under-floor heating as it works at a lower temperature than radiators.

A typical 8kW system costs between £6,400 - £9,600 plus the price of the distribution system, although this is variable with each property and location. Based on current fuel prices, a ground source heat pump with a CoP of 3-4 can be cheaper than space heating fuelled by oil, LPG and electric storage heaters.

To find out how to get ground source heat pumps please click on our Micropower Council member links below: