Low-carbon technologies come in many forms, one of the most obvious being the solar panels now found on many buildings around the UK. A less obvious but increasingly popular option is to harness heat (geothermal) energy from the ground through the use of a ground source heat pump (GSHP). This Information Paper provides an introduction to how GSHPs work and the applications that they can be used for. It also looks at two case studies where GSHPs have been installed. Most importantly, it explains how GSHPs represent a low-carbon energy option. Contents Introduction What is geothermal energy? How do ground source heat pumps work? Applications Case studies - North Kent Police Station, Gravesend - Hanson EcoHouse, BRE Innovation Park, Watford Further reading Useful contacts