Ground Source Heat Pumps

A ground source heat pump provides a clean way to heat buildings. It makes use of solar energy stored in the ground to heat buildings. Ground source heat pumps consist of a network of fluid filled boreholes, a compressor and pump unit. The fluid filled pipes are buried into the ground to absorb heat. A mixture of water and antifreeze is circulated around the underground loops of pipe. Heat from the ground is absorbed into the fluid, then passes through a heat exchanger into the heat pump.

The compressor unit raises the temperature of this fluid through compression, and a heat exchanger transfers the warmth to the water that circulates round the central heating system. The heat is then transferred to the property via radiators or under floor heating. Once the water is cooled it is pumped back out to the buried pipework and the cycle begins again. The whole system is powered by electricity but can also be powered by energy from renewable sources such as a wind turbine or solar panel.

Case study: Bristol City Council, Ashton Rise

Bristol City Council built 133 new energy-efficient homes comprising of 2, 3 and 4-bedroom houses and 1 and 2-bed apartments as part of the commitment to build 2,000 new homes in the city including 800 affordable homes.

A mix of 3kW and 6kW low carbon ground source heat pumps were installed as the heating and hot water system. Shared Ground Loop Array design features decentralised ground source heat pumps, an individual ground source heat pump per dwelling and connected network of pipes which circulate heat at ambient temperatures (-5°C to 20°C) from the ground supplied via clusters of ground arrays.

The shared ground loop system transfers ambient temperature low grade heat energy from the ground to individual ground source heat pumps located inside each individual dwelling. Each ground source heat pump then upgrades the ground’s heat energy to provide independently controllable heat via radiators or underfloor heating and hot water to a cylinder tank.