Geothermal heat pump
A geothermal heat pump, also called a ground-source heat pump, uses the relatively steady temperature below ground to heat and cool buildings. It moves heat with buried loops, circulating fluid, and a heat pump rather than burning fuel at the point of use.
What a geothermal heat pump is
A geothermal heat pump is a building heating and cooling system that exchanges heat with the ground or a water source. It is not the same as a geothermal power plant that uses deep hot resources to generate electricity. Most building-scale systems use shallow ground temperatures as a steady thermal reservoir.
How the loop works
Pipes are buried in the ground, submerged in a pond, or placed in vertical boreholes. A water-based fluid moves through the loop and exchanges heat with soil, rock, or water. The heat pump then concentrates or rejects that heat through a refrigeration cycle, much like an air conditioner that can run in either direction.
Heating and cooling seasons
In cold weather, the loop absorbs heat from the ground and the heat pump lifts it to a useful indoor temperature. In hot weather, the system carries indoor heat back into the ground. Because underground temperatures vary less than outdoor air, the heat pump can often work with a smaller temperature difference.
Closed and open loops
Closed-loop systems keep the circulating fluid inside buried pipe. They can be horizontal, vertical, pond-based, or arranged in other site-specific patterns. Open-loop systems use groundwater or surface water directly, which can be efficient but depends on water quality, permits, discharge rules, and long-term well performance.
Where they fit best
Good candidates include buildings with enough land or drilling access, long heating and cooling seasons, high energy prices, or owners who can value lower operating costs over many years. The system must be sized for the building load, local geology, soil moisture, groundwater conditions, and available installation space.
Costs and maintenance
The buried loop can last a long time when designed and installed well, but access is difficult after construction. The indoor heat pump, pumps, controls, filters, and air or water distribution system still need normal maintenance. A poor design can create comfort problems, high pumping energy, or ground temperature drift.
Why it matters
Geothermal heat pumps can reduce building energy use, cut peak electricity demand, and support lower-emission heating when the power supply is cleaner. They are one practical path for building decarbonization, especially where air-source heat pumps face extreme outdoor temperatures or where shared thermal networks are possible.