A ground source heat pump is a low‑carbon heating and cooling system that moves heat between your home and the ground instead of burning fuel.

What is a ground source heat pump?

A ground source heat pump (GSHP), also called a geothermal heat pump, uses buried pipes and a heat‑pump unit to extract low‑temperature heat from the ground and upgrade it to a useful temperature for space heating and hot water. It can also run in reverse, dumping heat back into the ground to provide cooling in summer.

Think of it like a fridge in reverse: a fridge moves heat from inside the box to the room; a ground source heat pump moves heat between your house and the earth.

Key idea

  • The ground a few metres down stays at a fairly constant temperature all year, usually around the average annual air temperature for your region.
  • The heat pump exploits that stable temperature to work much more efficiently than systems that have to fight very hot or very cold air.

How it works (quick step‑by‑step)

  1. Ground loop collects heat
    • Plastic pipes (the “ground loop”) are buried horizontally in trenches or vertically in boreholes and filled with a water–antifreeze mixture.
 * This fluid circulates through the ground, absorbing low‑grade heat from soil or rock.
  1. Heat enters the heat pump
    • The warmed fluid comes into the indoor heat‑pump unit and passes through a heat exchanger called an evaporator.
 * Heat is transferred into a refrigerant that boils at a very low temperature and turns into a gas.
  1. Compressor boosts the temperature
    • An electrically driven compressor squeezes the refrigerant gas, raising its temperature.
 * Now it is hot enough to be useful for heating water and radiators or underfloor heating.
  1. Heat delivered to your home
    • The hot refrigerant gas passes through a condenser, giving its heat to your home’s heating and hot‑water circuit.
 * After releasing heat, the refrigerant cools back to a liquid.
  1. Cycle resets
    • The refrigerant goes through an expansion valve, dropping in pressure and temperature so it can absorb heat again.
 * The ground‑loop fluid, now cooler after giving up its heat, returns underground to pick up more.

In cooling mode, valves reverse the direction of heat flow so heat is taken from the house and rejected into the ground.

Main components (at a glance)

  • Ground loop (collector pipes) : Buried plastic pipes in trenches or boreholes carrying the antifreeze mixture that exchanges heat with the ground.
  • Heat‑pump unit : Indoor unit with compressor, refrigerant loop, heat exchangers (evaporator and condenser), expansion valve, and controls.
  • Distribution system : Underfloor heating, low‑temperature radiators, or air handlers, plus a hot‑water cylinder.
  • Controls : Thermostats and smart controls that optimise operation over the seasons.

Types of ground loops

[10][3] [10][3] [3][10] [10][3] [10] [10] [3] [3]
Type How it’s installed Best when…
Horizontal loops Pipes laid in shallow trenches over a wide area of land. You have plenty of garden/land and prefer lower drilling costs.
Vertical boreholes Pipes lowered into deep, narrow boreholes (often 50–150 m). Land is limited but drilling is feasible; often used for larger buildings.
“Slinky” / spiral loops Coiled pipes placed in trenches to get more length into a small area. Medium plots where you need more pipe length than straight trenches allow.
Pond / lake loops Pipes submerged in a suitable body of water. You have access to a nearby pond or lake with sufficient volume.

Why people install them

Benefits

  • High efficiency
    • GSHPs are among the most efficient heating and cooling technologies available, because they use stable ground temperatures and move heat rather than creating it by burning fuel.
* They typically use much less electricity than resistive electric heating for the same heat output.
  • Low carbon and no on‑site combustion
    • They do not burn gas, oil, or propane and produce no on‑site combustion emissions.
* When powered with renewable electricity, they can be effectively carbon‑neutral in operation.
  • Year‑round comfort
    • One system can deliver both heating and cooling, plus domestic hot water.
* The stable ground temperature helps performance stay strong during extreme weather.
  • Long life
    • Underground loops can last several decades if installed correctly, often beyond the life of the indoor unit, which itself can last many years with maintenance.

Trade‑offs and challenges

  • Higher upfront cost
    • Drilling or trenching for the ground loop and installing the system costs more upfront than many conventional boilers or air‑source heat pumps.
  • Site constraints
    • You need either enough land for horizontal loops or suitable geology and access for borehole drilling.
* Soil and rock type affect how well heat transfers and therefore how much pipe you need.
  • Best with low‑temperature emitters
    • GSHPs work most efficiently with systems like underfloor heating or large radiators that can deliver comfort at lower water temperatures.

Where they’re used and current context

Ground source heat pumps are used in everything from individual homes to large commercial or district heating systems. In many countries they are viewed as a key technology for cutting building emissions and are supported by incentives or rebates that help with upfront cost. Interest has grown in the mid‑2020s as governments push for electrification of heating and expansion of clean energy.

Multiple viewpoints (is it right for you?)

  • Homeowners with land
    • Often see GSHPs as a way to lock in stable, low running costs and reduce exposure to fuel‑price swings, especially if they plan to stay long term.
  • Urban or space‑constrained properties
    • May find borehole systems technically possible but more expensive; sometimes an air‑source heat pump is chosen instead.
  • Climate and policy planners
    • View ground source systems as infrastructure that can connect to shared loops or district networks, supporting dense, low‑carbon heating in communities.

TL;DR: A ground source heat pump is a highly efficient, electrically driven system that uses buried pipes and a heat‑pump unit to move heat between your home and the ground, providing low‑carbon heating, cooling, and hot water from the stable temperature below the earth’s surface.

Information gathered from public forums or data available on the internet and portrayed here.