The short answer
A ground source heat pump (GSHP) installed in a UK home typically costs £18,000 to £35,000 before any grant — considerably more than an air source system. The extra cost comes almost entirely from the ground loop: either horizontal pipes buried in trenches across a garden, or vertical boreholes drilled deep into the ground, which require specialist drilling equipment. The same Boiler Upgrade Scheme £7,500 grant applies in England and Wales, and installations benefit from 0% VAT. In return, ground source systems usually achieve a higher and more stable efficiency (SCOP) than air source because ground temperature is steadier than air through winter. They suit larger properties, homes with plenty of land for trenches, or new builds where groundworks are already underway.
Ground source heat pumps cost more upfront than air source, and the reason is the ground loop. Knowing how the loop is installed — and why it changes the figure so much — explains the price gap.
Ground source heat pump cost
- Typical installed cost (before grant)£18,000–£35,000
- Main cost driverGround loop / borehole drilling
- Boiler Upgrade Scheme grant£7,500 (England & Wales)
- VAT on installation0% (until March 2027)
- Typical efficiency advantageHigher, steadier SCOP than air source
Why ground source costs more than air source
The heat pump unit itself is broadly comparable to an air source unit. The cost difference is the ground array — the buried pipework that collects heat from the ground:
- Horizontal ground loops: pipes laid in trenches roughly 1–2 metres deep, spread across a garden. This needs a large area of land and significant excavation, but avoids drilling. It is the cheaper of the two ground-loop options where land is available.
- Vertical boreholes: pipes installed in deep boreholes drilled into the ground, often 60–150 metres deep. Boreholes need far less surface area, making them the option where garden space is limited — but the specialist drilling rig and crew make them the more expensive route.
Because ground temperature stays relatively constant year-round, the heat source does not drop in efficiency on the coldest days the way air does. That stability is the main performance benefit you are paying for.
| Cost element | Air source (for comparison) | Ground source |
|---|---|---|
| Heat pump unit | Included | Comparable |
| Heat collector | None (uses outdoor air) | Ground loop or boreholes — major cost |
| Groundworks / drilling | None | Trenching or borehole drilling |
| Typical installed total (before grant) | £8,000–£14,000 | £18,000–£35,000 |
| Boiler Upgrade Scheme grant | £7,500 | £7,500 |
| Efficiency (SCOP) tendency | Good, drops in cold | Higher and steadier |
Indicative UK figures for guidance. Sources: Energy Saving Trust and Nesta cost guidance. Borehole vs trench choice depends on land availability and ground conditions.
What drives the price within the range
Ground source quotes vary even more than air source because the groundworks dominate the cost:
- Borehole vs trench: boreholes cost more per metre because of drilling, but need little land. Trenches are cheaper to dig but need a large garden.
- Ground conditions: rocky or difficult ground increases drilling cost and time.
- System size: larger homes need a longer ground loop or deeper boreholes to collect enough heat.
- Number of boreholes: bigger heat demand can require more than one borehole.
- Internal system: as with air source, a hot water cylinder, radiator changes and controls form part of the price.
Trenches versus boreholes in more detail
The ground loop choice is the biggest single decision in a ground source installation, and it shapes both cost and disruption:
- Horizontal trenches: pipe is laid in trenches typically a metre or two deep, spread across the garden. The excavation is significant and temporarily disrupts the garden, but it avoids specialist drilling, so it is usually the cheaper ground-loop option where there is enough land. The rule of thumb is that you need a sizeable area of garden relative to the home's heat demand.
- Vertical boreholes: a drilling rig bores deep holes, often tens to over a hundred metres deep, and the pipe loop is installed in them. Boreholes need only a small surface footprint, making them the choice for homes with limited garden space, but the drilling rig, crew and time make them more expensive. Larger heat demands can need more than one borehole.
- Ground conditions matter: rocky, unstable or waterlogged ground can increase drilling difficulty and cost. A ground assessment informs which approach is feasible and what it will cost.
Because these groundworks dominate the price, the gap between a straightforward trench installation and a deep borehole installation can be large. This is the main reason ground source quotes vary so much more than air source quotes.
Grant, VAT and the long-term picture
The same financial supports apply to ground source as to air source:
- Boiler Upgrade Scheme: a £7,500 grant in England and Wales towards an MCS-certified ground source installation. Because the total is higher, the grant covers a smaller share of the cost than it does for air source.
- 0% VAT on the installation, currently until March 2027.
- Home Energy Scotland offers separate grant-and-loan support in Scotland.
The trade-off is upfront cost against running efficiency. A ground source system's steadier, often higher SCOP can mean lower running costs over its life, but the much larger initial outlay means the payback period is longer than for air source in most homes.
There is also a longevity point that affects the lifetime sum. The buried ground loop is an exceptionally long-lived component — it has no moving parts and is expected to last for decades, well beyond the life of the heat pump unit itself. So while the groundworks are the most expensive part to install, they are effectively a one-time cost: if the heat pump unit is eventually replaced, the ground loop generally stays in place and serves the replacement. For a home that plans to stay put for the long term, that durability is part of the case for ground source despite the higher entry price, and it is why ground source is often favoured where the disruption and cost of the groundworks can be justified over a long ownership horizon.
Frequently asked questions
Is a ground source heat pump more efficient than air source?
Generally yes. Ground temperature is more stable than air temperature through the year, so a ground source heat pump tends to achieve a higher and steadier seasonal performance (SCOP), especially on cold days when air source efficiency falls. The efficiency gain has to be weighed against the much higher installation cost.
Do I need a big garden for a ground source heat pump?
For a horizontal ground loop, yes — the trenches need a large area of land. If you do not have the space, vertical boreholes need only a small surface footprint but cost more because of the drilling. The choice between trenches and boreholes usually comes down to how much land you have and the ground conditions.
Does the £7,500 grant cover ground source too?
Yes. The Boiler Upgrade Scheme grant of £7,500 applies to MCS-certified ground source heat pump installations in England and Wales, the same amount as for air source. Because ground source costs more, the grant covers a smaller proportion of the total, so the net cost is still higher than for air source.
Sources & further reading
- Energy Saving Trust — ground source heat pumps
- gov.uk — Boiler Upgrade Scheme
- MCS — find a certified heat pump installer
Figures on this page are typical UK ranges drawn from published sources and depend on your specific home. They are guidance, not a quotation or guaranteed saving.