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Air Source vs Ground Source Heat Pump: Which Is Right for Your Home?
Posted on 20th Aug 2026
In Brief
Air source heat pumps cost £7,000 to £13,000 installed and only need space for an outdoor unit, while ground source heat pumps cost £15,000 to £40,000 and need either a large garden for horizontal loops or a borehole, though they tend to run slightly more efficiently thanks to the stable underground temperature. Both qualify for the same Boiler Upgrade Scheme grant, up to £7,500, or £9,000 for eligible off-grid homes until 31 March 20
Choosing between an air source heat pump and a ground source heat pump usually comes down to three things: your budget, your outdoor space, and how much you want to future-proof your heating for decades rather than years. Both technologies do the same essential job, moving heat from outside into your home rather than burning fuel to create it, but how they do it, and what they cost, differs enough that it’s worth understanding both before you get a quote.
We install and maintain both across Dorset, Wiltshire and Somerset, so this isn’t a theoretical comparison, it’s the same conversation we have with homeowners at the start of nearly every heat pump survey.
How each system actually works
Air source heat pumps
An air source heat pump pulls warmth from the outside air, even on cold days, and uses it to heat your home and hot water. The only outdoor requirement is space for the unit itself, roughly a 2m by 2m footprint against an outside wall.
Ground source heat pumps
A ground source heat pump extracts heat from underground instead, using either horizontal loops buried in trenches across your garden, or a vertical borehole drilled much deeper. We’ve covered the space each option needs in detail in our guide to how much space a ground source heat pump needs, but the short version is that horizontal loops need a sizeable garden, while boreholes need very little surface space but cost more to install.
Cost comparison
| Air source | Ground source | |
|---|---|---|
| Typical installed cost | £7,000 to £13,000 | £15,000 to £25,000 (horizontal loops) or £25,000 to £40,000 (borehole) |
| Typical running cost | £500 to £1,400 a year | Broadly similar, often slightly lower thanks to more consistent efficiency |
| Boiler Upgrade Scheme grant | Up to £7,500, or £9,000 off-grid | Same |
We’ve broken the air source figures down in more detail in our air source heating cost guide, including what affects the price and what a typical UK household spends to run one.
Space requirements
This is usually the deciding factor before cost even comes into it. An air source heat pump needs almost nothing beyond a bit of outside wall space and clearance for airflow around the unit. A ground source system needs either roughly two to three times your home’s floor area for horizontal loops, so a 100m² house would need at least 200 to 300m² of open land, or a borehole drilled 50 to 150 metres down, which takes up very little surface space but needs specialist drilling equipment to install.
If your garden is small, courtyard-sized, or already landscaped, that alone often settles the decision in favour of air source.
Efficiency and consistency
Both technologies are highly efficient. Air source heat pumps typically deliver three to four units of heat for every unit of electricity used, and ground source systems perform similarly, often edging slightly higher.
The real difference is consistency. Air temperature swings with the weather, so an air source heat pump has to work hardest exactly when it’s coldest outside and least efficient. Ground temperature a few metres down stays fairly stable year round, whatever’s happening above ground, which is why ground source systems tend to hold their efficiency more evenly through a cold snap. The government’s guide to heat pumps covers the general principles behind both technologies if you’d like the fuller picture.
In practice, for most well-insulated homes in Dorset and Wiltshire, this difference is smaller than the upfront cost gap, but it’s worth knowing about, particularly for larger or older properties with higher heat demand.
Grants: the same for both
Both air source and ground source heat pumps qualify for the same Boiler Upgrade Scheme grant. Most households can claim up to £7,500, and if your home is off the gas grid and currently heated by oil or LPG, you may qualify for an increased grant of £9,000, available until 31 March 2027. We’ve covered the full eligibility criteria in our guide to the £9,000 Boiler Upgrade Scheme grant.
Which one suits your home
As a general rule:
- Air source suits most homes, particularly where garden space is limited, budget is a bigger factor, or you want a more straightforward installation.
- Ground source suits larger rural properties with plenty of land, especially where you’re already having groundworks done for another reason, and where the slightly higher long-term efficiency is worth the extra upfront cost.
Neither is a wrong choice. We’ll always talk through your property, your budget and your priorities as part of a proper survey, rather than defaulting to one over the other.
Frequently Asked Questions
Is a ground source heat pump always more efficient than air source?
Not always, but it tends to hold its efficiency more consistently through winter, since the ground stays at a more stable temperature than the air. For a well-insulated, average-sized home, the practical difference is often small.
Can I install a ground source heat pump if I don't have a big garden?
Yes, a vertical borehole needs very little surface space, though it costs more than horizontal loops because of the specialist drilling involved.
Do both types qualify for the same grant?
Yes. Both air source and ground source heat pumps are eligible for the Boiler Upgrade Scheme, up to £7,500 standard, or £9,000 for eligible off-grid homes replacing oil or LPG heating until 31 March 2027.
Which is cheaper to run day to day?
Running costs are broadly similar for both, typically £500 to £1,400 a year depending on your home's size, insulation and how you use the system. Ground source systems sometimes come in slightly lower thanks to their more stable efficiency.
Not sure which is right for you?
The only way to know for certain is a proper site survey. We offer a free, no-obligation visit to assess your property, your garden, and your heating needs, then talk you through whether air source or ground source makes more sense for your home. Get in touch or give us a call on 01747 858 852.
