Ground-source heat pump
A heat pump that exchanges heat with the ground through buried loops or boreholes, benefiting from stable soil temperatures for high seasonal efficiency.
A ground-source heat pump (GSHP), sometimes called a geothermal heat pump, circulates water-glycol brine through closed loops in the ground. Below about 10–15 m, ground temperature is nearly constant at roughly the local mean annual air temperature (8–12 °C in much of Europe), so the source stays warm in winter and cool in summer.
- Vertical boreholes: 50–200 m deep, 110–150 mm diameter; typical extraction 40–60 W per metre in good rock
- Horizontal loops: buried 1.2–2 m deep, needing roughly 1.5–3 times the heated floor area of land
- Open loops: pump groundwater directly, where permitted
Ground extraction = heat output x (1 - 1/COP)
Example: 10 kW at COP 4.5 needs 7.8 kW from ground; at 50 W/m ≈ 156 m of borehole
Typical SCOP is 4.5–5.5 at 35 °C flow, higher than air-source units, with no defrost losses and no outdoor fan. Drilling makes installation more expensive (often 15,000–30,000 EUR for a house), so GSHPs suit larger buildings, new builds and shared-loop networks. Summer passive cooling can recharge the ground. Size a system with the ground-source heat pump calculator.
Related terms
All terms →- Heat pump
A device that uses a refrigeration cycle to move heat from a cooler source (air, ground, water) to a warmer sink, delivering 2–5 units of heat per unit of electricity.
- Air-source heat pump
A heat pump that extracts heat from outdoor air, supplying space heating and hot water (air-to-water) or warm air (air-to-air), and the most widely installed type.
- COP (Coefficient of Performance)
The ratio of useful heat (or cooling) delivered by a heat pump to the electrical energy it consumes, measured at a specific operating point.
- SCOP (Seasonal COP)
A heat pump's average coefficient of performance over a standardised heating season, weighting test points by how often each outdoor temperature occurs.
- Geothermal gradient
The rate at which temperature increases with depth in the Earth's crust, averaging about 25 to 30 °C per kilometre away from tectonic plate boundaries.