1. Location Issues - GSHPs do not generally use deep geothermal heat energy from the core of the earth to heat buildings. From several metres down to 100 metres or so the ground temperature is more or less uniform in the UK; there are obvious exceptions such as Bath and Southampton. Instead, ground source heat pumps absorb low-grade solar energy during the winter, which must be re-charged during the summer. The ground acts as a battery, which means that incorrectly designed or sized closed loop ground arrays can over-cool the ground surrounding the pipe, leading to much lower outputs and efficiencies from the heat pump.

A knowledge of ground temperatures and the underlying geology can lead to improved system design and can help the cost effectiveness of an installation. It is recommended that installation is done by a recognized installer.      

2. Sizing - Sizing of the heat pump and the ground loops is essential for the efficient operation of the system. If sized correctly a GSHP can be designed to meet 100% of space heating requirements. It is recommended that that sizing a system is a job for a specialist and heating needs should be properly assessed.

The sizing of a system is very sensitive to heat loads and should therefore be installed into properties with high-energy efficiency standards, particularly new build. It is a good idea to explore ways of minimising space heating and hot water demand by incorporating other energy efficiency measures.

3. Site Issues - The performance of a closed loop GSHP system depends on the local site conditions. While for large commercial installations a thermal test may be carried out smaller, domestic, installations generally have to be designed using rules-of-thumb and average site properties. Site factors can affect both the heating and cooling performance of the heat pump and the drilling-trenching methods and costs.

4. Planning issues - As the ground loop is not visible once installed, no planning permission is required. However, the householder should check about any services that may be located in the possible site for the ground loop (e.g electricity cables, gas/water pipes). The heat pump installation would also, of course, need to meet relevant building regulations requirements.