Air source or ground source: which heat pump do you need?
Short answer
Most UK homes will start by considering an air-source heat pump because it is simpler and usually cheaper to install. Ground-source systems can be very efficient, but they need land or boreholes and usually cost much more upfront. The right choice depends on your site, heat demand, budget and how much disruption you can accept.
Last checked 24 September 2026 · 2 sources
What is the difference between air source and ground source?
The heat pump cycle is similar in both systems. The main difference is where the heat comes from.
An air-source heat pump takes heat from outdoor air. A ground-source heat pump takes heat from the ground through buried pipework or boreholes.
Ground temperatures are more stable than air temperatures through winter. Historically, that gave ground-source systems an efficiency advantage.
The installer in our source interview said newer air-source units using R290 refrigerant have narrowed that gap considerably. That is an installer’s view, and actual performance still depends on the individual system.
Why is ground source more expensive?
The heat pump itself is only part of the job. Ground-source systems also need groundworks.
That may mean horizontal pipe loops across a large area of land or vertical boreholes drilled deep into the ground. Those works can make ground source substantially more expensive than air source.
When does ground source make sense?
It can be attractive when you have:
- enough land or a practical borehole location;
- a high and steady heat demand;
- a larger upfront budget;
- a long-term reason to maximise efficiency;
- a project where groundworks are already planned.
For a typical existing home with limited outdoor space, air source is usually the simpler route.
Is one type automatically cheaper to run?
No. Ground source often has a strong efficiency case, but an excellent air-source system can outperform a badly designed ground-source one.
System design, flow temperature, controls and the tariff you pay still matter.
What should I do next?
Ask installers to compare both options on annual energy use, not just installation cost. Include groundworks, radiator changes, maintenance, expected seasonal efficiency and the grant you can claim.
Sources
- Source interview with Heat Geek installer, air-source versus ground-source discussion.
- Ofgem, Boiler Upgrade Scheme — Property owners, checked 24 September 2026.
Last checked: 24 September 2026