Ground-source energy is the energy stored in the ground from to the sun’s radiation. The temperature at depths of ca. 1.5m is near constant throughout the year, typically ranging from 7-12°C in Northern Europe. To extract this energy, heat transfer fluid is circulated through underground pipes and heated by the surrounding soil. A ground-source heat pump (GSHP) then takes this temperature difference and converts it into useable energy for heating and cooling a building. A well-designed ground-source heat pump offers a Coefficient of Performance (CoP) of between 3-4, which means for every 1 unit of electricity used by the heat pump, around 3-4 units of renewable energy are generated. Ideally, a heat pump is combined with underfloor heating and a highly insulated building for optimum performance.
The UK governement has introduced an incentive scheme called the Renewable Heat Incentive (RHI) to increase the uptake of renewable heat technologies. Ground source heat pumps are included in this for both residential (scheme starts Spring 2014) and non-domestic projects (since November 2011). The tariffs for commercial GSHPs was increased significantly by DECC in December 2013. GSHPs have lower running costs than both air-source heat pumps (ASHP) and biomass boilers.