A ground source heat pump (GSHP) uses pipes buried in the ground to extract heat, and then use it for heating water or air in a building. The pump used to extract the heat needs to be powered by electricity, so to make it a completely renewable technology you should generate your own electricity using a renewable energy source such as solar PV.
The buried pipe is a loop, called a ground loop. It can be laid coiled, flat or vertical. The electric pump circulates a mixture of water and anti-freeze through the pipe and while the liquid travels around, it is warmed by the heat from the ground. The liquid returns to the building and into your heating system (underfloor or warm air heating works best). The longer the loop, the more heat the liquid absorbs and generally the better the results will be.
Is my building suitable? You need to have a ground area that is suitable for digging a trench or borehole and accessible to digging equipment. Generally, it is better suited to new build properties or those undergoing major (ground up) refurbishment. As a guide, for a highly insulated 3 bedroom house, you will require approximately 50 square metres.
What are the benefits? Ground source heat pumps generally have a high reliability and require low maintenance. There is also no need for storage of fuel and the pump only occupies the space of a large domestic fridge. And because the ground temperature stays constant below the surface, it can work all year round. It also does not require planning permission.
How much does it cost? Cost will depend on the size and specification of your property. Typically, it could cost between £15,000 and £20,000 for a domestic install, plus any additional costs for upgrading your existing heating system.