Ground Source Heat Pumps 2026

£28,000. That's what a neighbour of ours paid for a ground source heat pump last winter, fully installed with a 90-metre borehole. Two roads away, someone with a bigger garden went horizontal and paid £18,000. Same technology, same grant, wildly different price. The difference was the ground.

Ground source heat pumps pull heat from the earth instead of the air. See our guide on heat pump noise and placement for more detail. The ground below about 1.2 metres stays at a steady 8°C to 12°C all year, regardless of what the weather is doing above. That consistency is the whole point. While an air source unit works harder as temperatures drop, a ground source system barely notices winter. The trade-off is cost and disruption: you need either a large garden for horizontal trenches or the budget for vertical boreholes.

How Is This Different from Air Source?

Both types use the same refrigerant cycle to move heat. The difference is where they collect it from.

An air source heat pump has a fan unit outside your house that pulls warmth from the ambient air. Works well, but performance drops as the air gets colder. At 7°C you might see a COP of 4.0. At -5°C that could fall to 2.5.

A ground source system buries pipes in the earth, either in horizontal trenches or vertical boreholes. The ground temperature barely changes with the seasons. So the COP stays more consistent, typically 3.5 to 5.0 year-round according to the Energy Saving Trust. No fan noise either. The outdoor element is invisible once the ground is reinstated.

The practical difference? Ground source delivers roughly 15% to 30% more heat per unit of electricity over a full heating season. That efficiency gap compounds every single year you own the system.

What Does It Cost?

Here's where most people stop reading and go back to air source. The upfront numbers are genuinely high.

These figures come from MCS installer data and include the heat pump unit, ground loop installation, hot water cylinder, controls and commissioning. The ground loop itself, the trenching or drilling, accounts for 40% to 60% of the total cost, which is why the price varies so much between horizontal and borehole systems.

An equivalent air source installation runs £10,000 to £16,000 before the same £7,500 grant. So ground source costs roughly double. That's the honest starting point.

The BUS Grant: Same £7,500

The Boiler Upgrade Scheme gives you £7,500 towards a ground source heat pump in England and Wales, exactly the same amount as for air source. Your MCS-certified installer applies for it. The grant comes straight off your invoice. You don't deal with Ofgem or fill in government forms.

The scheme has processed over 100,000 vouchers since its 2022 launch, per GOV.UK data. Ground source installations make up about 5% of BUS applications according to Ofgem quarterly statistics, which tells you something about how many people are willing to pay the premium.

If your household income qualifies, ECO4 or the Warm Homes Plan could cover even more. Open the eligibility checker to see what applies.

Horizontal vs Vertical: Which Ground Loop?

This is the decision that drives most of the cost difference.

Horizontal Trenches

Pipes laid in trenches about 1.2 metres deep, running back and forth across your garden. Cheaper because trenching is simpler than drilling. A typical three-bed semi needs 200 to 300 metres of pipe spread across 100 to 200 square metres of garden.

The catch: you need that much garden. And the ground above the pipes can't have anything heavy on it afterwards, no patio, no extension, no large trees with deep roots. The lawn goes back on top and you'd never know the pipes were there, but the land is effectively reserved.

Horizontal systems are slightly less efficient than boreholes because the ground at 1.2 metres is more affected by seasonal temperature swings than the ground at 50 to 100 metres. The difference is small, perhaps 5% to 10% over a year, but it exists.

Vertical Boreholes

A drilling rig bores one or more holes 50 to 100 metres deep. Pipes go down, loop at the bottom, and come back up. The footprint on your garden is tiny, just the borehole cap, which is about the size of a dinner plate.

Boreholes suit smaller gardens, urban properties, or homes where you don't want to dig up the entire lawn. They're more expensive because drilling rigs cost more to mobilise than a digger, and the work takes longer. A single 90-metre borehole typically costs £6,000 to £10,000 just for the drilling.

Deep ground temperatures are more stable, so boreholes deliver marginally better year-round performance. For larger properties with high heat demand, two or three boreholes might be needed.

Is My Garden Big Enough?

This is the question that rules ground source in or out for most people.

For horizontal trenches, the rule of thumb is roughly two to three times your home's floor area. A 90-square-metre house needs 180 to 270 square metres of usable garden. That's a decent-sized plot. Terraced houses and most urban semis won't have it.

For boreholes, you need access for a drilling rig (about 3 metres wide) and enough distance from boundaries, typically 5 metres from any building or property line. If a rig can get into your garden, a borehole is probably feasible.

A site survey is essential. A ground source installer will assess your soil type (clay retains heat well, sandy soil less so), check for underground services, and calculate whether horizontal or vertical makes more sense. Some installers offer a combined approach: shorter boreholes plus a smaller trench area, which can work on mid-sized plots.

Running Costs vs Air Source: The 15-Year View

Here's where ground source claws back its higher upfront cost. The comparison below uses a typical three-bedroom semi with 12,000 kWh annual heat demand, April 2026 Ofgem price cap rates, and real-world SCOP figures from MCS data.

Over 15 years, ground source saves roughly £2,760 in running costs compared to air source. But the upfront gap is £11,000. On pure economics over 15 years, air source still wins by about £8,200 in total cost of ownership for a typical semi.

The maths shift in ground source's favour when:

• Your home has high heat demand (large detached, poorly insulated). The efficiency gap saves more in absolute terms.
• Electricity prices rise. Every penny per kWh increase benefits the more efficient system disproportionately.
• You plan to stay 20 years or more. The ground loop lasts 50+ years. The heat pump unit itself lasts 20 to 25 years. Air source units typically last 15 to 20 years, so you may need a second unit while the ground source loop keeps going.
• You add solar panels. Ground source's higher COP means each free kWh of solar electricity produces more heat.

Here's what most guides won't tell you: for a standard three-bed semi, air source is almost always the better financial choice. Ground source makes economic sense for larger homes with high heat demand, or for people who value the silence, the longevity, and the consistency of performance over the lowest upfront cost. If you're comparing heat pump brands for a typical home, air source is where to start.

Planning Permission and Regulations

Ground source heat pumps in England and Wales generally fall under permitted development for the heat pump unit itself. But the ground works can trigger additional requirements.

Boreholes deeper than 15 metres may require notification to the Coal Authority in former mining areas. If your property is in a Source Protection Zone (near a drinking water source), the Environment Agency may need to approve the drilling. Your installer should check all of this as part of the site survey.

Horizontal trenches don't usually need planning permission, but if you're in a conservation area or the property is listed, check with your local planning authority first.

All installations must be carried out by an MCS-certified installer to qualify for the BUS grant and to meet Building Regulations Part L.

Who Should Get a Ground Source Heat Pump?

Ground source is the right choice if you tick most of these boxes:

• Large garden or land (200+ square metres for horizontal, or access for a drilling rig)
• High heat demand (detached house, older property, 15,000+ kWh per year)
• Planning to stay in the property long-term (15+ years)
• You value quiet operation (no outdoor fan unit)
• Budget allows the higher upfront cost even after the grant

If your garden is small, your heat demand is moderate, or budget is the priority, an air source heat pump will serve you well at a fraction of the upfront cost. Before committing to either system, it's worth reading our heat pump installation guide to understand the full process and what to expect. Check our guide on how heat pumps work for the full picture on both types.

Open the eligibility checker. Two minutes. You'll see exactly which grants apply to your home and whether the numbers work for ground source.