A ground source heat pump is the most efficient way to heat a UK home, and the hardest to install. The unit itself is the small part of the job. What decides whether it is possible, and what it costs, is the ground array buried outside: trenches across a garden, or boreholes drilled up to 200 metres down.
The Energy Saving Trust puts a typical trench installation at around £15,000. Boreholes cost considerably more. Both qualify for the same £7,500 Boiler Upgrade Scheme grant as an air source heat pump, which is where the decision usually starts.
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- A trench ground loop installation is typically around £15,000 - the Energy Saving Trust’s figure, before the grant is applied
- The £7,500 Boiler Upgrade Scheme grant applies, rising to £9,000 off the gas grid - the same rates an air-to-water air source heat pump gets, and heat pumps are zero-rated for VAT until 31 March 2027
- A newbuild three-bed needs two trenches of 30 to 40 metres - if you do not have that much accessible garden, you are looking at boreholes 75 to 200 metres deep instead
- Efficiency is the entire argument: 3 to 4 units of heat per unit of electricity - at the bottom of that range gas is still cheaper to run, at the top the heat pump wins clearly
- The heat pump lasts over 20 years and the buried ground array far longer - Kensa rates the array at 100 years, against 7 to 10 years for an oil boiler
What Does a Ground Source Heat Pump Cost?
The Energy Saving Trust puts a ground source installation at around £15,000 where the ground loop is buried in trenches. That is a typical figure rather than a range, and it assumes you have garden you can dig. If you need boreholes instead, EST states the cost is considerably more, and the job also needs a specialist thermogeological survey first.
It is worth being straight about the borehole number, because a lot of sites are not. No primary UK source publishes a borehole cost range. The figures you will see quoted elsewhere come from comparison sites rather than from installers, manufacturers or the Energy Saving Trust, so we have not repeated them here. The only honest answer is that boreholes cost meaningfully more than trenches and the gap depends on your geology, which is exactly what the survey exists to find out.
The heat pump unit is a smaller share of the total than most people expect. Kensa, the main UK ground source manufacturer, lists its Shoebox unit from £4,625 for the 3kW model and £6,200 for the 6kW. Those are unit prices only, with no groundworks, cylinder or installation included.
| Cost element | Figure | What it covers |
|---|---|---|
| Typical trench installation | Around £15,000 | Complete installation with a ground loop buried in trenches (Energy Saving Trust) |
| Borehole installation | Considerably more | No primary source publishes a figure. Also needs a thermogeological survey |
| Kensa Shoebox 3kW | From £4,625 | Heat pump unit only, flats and small homes |
| Kensa Shoebox 6kW | From £6,200 | Heat pump unit only |
| Boiler Upgrade Scheme grant | −£7,500 | England and Wales. £9,000 off the gas grid on oil or LPG |
| VAT | 0% | Zero-rated in residential property until 31 March 2027 |
Applied to the EST figure, a typical trench installation lands near £7,500 after the grant, or around £6,000 if your property is off the gas grid and heated by oil or LPG. That is competitive with a good air source heat pump installation before you count the running-cost difference.
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Trenches or Boreholes: What Actually Decides It
Space decides it, not preference. A ground loop in trenches is the cheaper option, but it needs a meaningful area of accessible garden with no trees, reachable by machinery from a road. Where that does not exist, boreholes are the alternative, and they need almost no surface area at all.
For a newbuild three-bedroom house, the Energy Saving Trust expects two trenches of 30 to 40 metres. A larger home, or an older one that is not well insulated, needs a bigger loop again. Tree roots rule ground out, and so does any area a digger cannot reach.
A borehole is only about 20 centimetres wide but somewhere between 75 and 200 metres deep, with the depth set by your heat demand and the geology under the property. Larger houses may need more than one. Because the ground is warmer the deeper you go, borehole systems can run more efficiently than trench systems, which partly offsets the higher cost.
Blocks of flats can share one large ground loop, with the heat pumps and pipework installed for the whole building at once and maintenance folded into service charges. Where that is not on the table, an air-to-air heat pump is usually the more realistic route for a small flat.
Indoors, expect a unit roughly 120cm by 60cm by 60cm, about the size of an American-style fridge. It often houses the hot water cylinder as well, so the space it needs is real and worth identifying before you get quotes.
The Grant, the VAT Break and What They Are Worth
In England and Wales the Boiler Upgrade Scheme pays £7,500 towards a ground source heat pump. That figure also covers water source systems and shared ground loops. Where the property sits off the gas grid and is currently heated by oil or LPG, the grant rises to £9,000 between 21 July 2026 and 31 March 2027.
Heat pumps installed in residential property are zero-rated for VAT until 31 March 2027, after which the reduced rate applies. Between the grant and the VAT treatment, the state is currently carrying a substantial share of a ground source installation, and both have end dates attached.
The scheme has capacity limits: 45kWth for an individual system, 70kWth for multiple systems, and 300kWth for shared ground loops. Domestic installations sit well inside these, but they matter for larger or shared commercial schemes. Our full guide to UK heat pump grants covers eligibility and the application sequence in detail.
Scotland runs its own support through Home Energy Scotland rather than the Boiler Upgrade Scheme, combining a grant with an interest-free loan. Northern Ireland has no equivalent heat pump grant at present. The Warm Homes Plan is set to put multiple billions into UK homes, including fully funded heat pumps for low-income households and low or zero-interest loans regardless of income, but the detail has not been published yet and it is not something you can apply for today.
Running Costs: Where Ground Source Wins and Where It Does Not
Ground source heat pumps deliver roughly 3 to 4 units of heat for every unit of electricity they use. That spread is the whole economic argument, because at the bottom of it a gas boiler is still cheaper to run and at the top the heat pump is clearly ahead.
Working from the Ofgem price cap for 1 July to 30 September 2026, with electricity at 26.11p per kWh, a ground source heat pump running at an efficiency of 3.0 delivers heat at about 8.70p per kWh. At an efficiency of 4.0 that falls to about 6.53p. A new gas boiler at 92% efficiency, with gas at 7.33p per kWh, delivers heat at about 7.97p.
So the honest answer is that a ground source heat pump beats mains gas on running cost only in the upper part of its efficiency range. The quality of the design is what puts it there, which is why the installer matters more than the badge on the unit.
| Heating system | Cost per kWh of heat | Basis |
|---|---|---|
| Ground source at efficiency 4.0 | About 6.53p | Electricity 26.11p per kWh |
| New gas boiler at 92% | About 7.97p | Gas 7.33p per kWh |
| Ground source at efficiency 3.0 | About 8.70p | Electricity 26.11p per kWh |
Against anything other than mains gas the case is much stronger. Kensa puts the running-cost saving against an oil boiler at 30 to 50%, and claims a 25% bill saving against mains gas where the system is paired with a smart meter and a flexible tariff. Both are the manufacturer’s own figures, and the gas comparison is conditional on that tariff, so treat them as a best case rather than a baseline. The pattern holds regardless: what you are replacing matters more than what you are buying, which is the same conclusion our heat pump versus gas boiler comparison reaches.
Ground Source or Air Source?
For most UK homes, air source is the right answer. It costs less, needs no groundworks, and takes the same £7,500 grant. Ground source earns its extra cost in a narrower set of cases, and being clear about which you are in saves a lot of wasted survey time.
Ground source makes sense when you have the land and the groundworks are straightforward, when you are building new and the trenches can go in before landscaping, when the property is large enough that the efficiency gain compounds into real money, or when there is nowhere acceptable to put an outdoor air source unit. It also runs at a stable efficiency through winter, because ground temperature barely moves while air temperature collapses exactly when you need heat most.
The counter-argument is simple. A ground source system is a construction project as much as a heating upgrade, and the groundworks are the part that overruns. If you are weighing the two, our guide on whether heat pumps are worth it covers the wider financial case, and heat pump sizing explains the heat loss calculation that both types depend on.
Is Your Property Suitable?
Three things decide it: usable outdoor ground, indoor space for the unit and cylinder, and a heating system that can run at a lower flow temperature than a gas boiler. The first is the one that rules properties out.
Most installations count as permitted development and need no planning permission, though listed buildings and conservation areas are the usual exceptions and are worth checking with the local planning office before you spend money on a survey. The Energy Saving Trust recommends getting quotes from at least three MCS-accredited installers, which is sensible on price alone and also necessary for the grant, since MCS certification is a Boiler Upgrade Scheme eligibility condition.
Radiators are the quiet cost. A ground source system running at 35 to 45°C cannot push heat through radiators sized for a boiler running at 70 to 80°C, so some will usually need upsizing. Our guide to heat pump radiators covers which rooms typically need changing and which do not, and it is worth reading before you accept a quote that leaves it vague.
How We Researched This Guide
Installation costs and all physical specifications come from the Energy Saving Trust’s ground source heat pump guidance, last updated 16 July 2026. Unit prices come from Kensa’s published product pages. Grant values, capacity limits and the VAT position come from GOV.UK and Ofgem. Running costs are calculated from the Ofgem price cap for 1 July to 30 September 2026.
Where we could not source a figure to a primary origin, we have said so rather than filling the gap. That applies to borehole installation costs and to the land area a ground loop needs, both of which are widely quoted online without a traceable source behind them.
