Commercial ground source heat pumps
How commercial ground source heat pumps and borehole systems work, why they cost more to build, and the circumstances in which that premium can be justified.
How a ground-source system works
A ground-source heat pump circulates a water and antifreeze mixture through pipework buried in the ground, collects low-grade heat and lifts it to useful temperatures in the heat pump. There are two main collector types:
- Vertical boreholes. Holes are drilled to depth and a closed loop is lowered in. They suit sites with limited surface area, which is common for commercial premises, but need drilling rigs, ground investigation and a regulatory check on borehole consents.
- Horizontal loops or slinky coils. Pipework is laid in trenches over a large area. They are cheaper per metre to install but need open land, which most urban business sites do not have.
Some designs use open-loop systems that draw groundwater, which brings extra permitting and water-quality issues and is a specialist route. Ask any designer which collector type is proposed and what ground investigation supports it. A thermal response test on a trial borehole is the usual way to confirm the ground’s properties before a full field is drilled.
Why the capital cost is higher
The heat pump itself is similar in kind to an air-source unit. The extra cost sits in the ground array: drilling, pipework, manifolds, trenching, reinstatement, ground investigation and the time those take. That is why published bands sit above air-source for the same output. The table repeats those in one installer guide (Fuse Energy, updated 8 July 2026), a secondary source whose bands overlap and are not consistent with each other. They are a planning scale, not a price.
| Thermal output | Air-source band | Ground-source band |
|---|---|---|
| 100 kW | £55,000 - £95,000 | £90,000 - £160,000 |
| 200-500 kW | £80,000 - £250,000 | £120,000 - £600,000 |
| 500 kW | £210,000 - £380,000 | £360,000 - £640,000 |
The width of the 200-500 kW ground-source band shows how site-specific the number is: geology, borehole depth and count, access for a rig and the length of pipework to the plant room all move it. The cost guide sets out the other price drivers and a running-cost method.
Two related questions come up early on a ground-source project. Whether air source would do the job for less disruption is covered in choosing between air source and ground source, and sites beside a river, lake or canal can read how water source heat pumps are licensed and designed.
Borehole cost and ground source heat pumps for commercial buildings
For ground source heat pumps for commercial buildings, the borehole field is usually the largest unknown in the budget: depth, number of boreholes, geology and rig access all change it. The separate guide to ground source heat pump borehole cost sets out what drives the figure and how to compare ground-investigation results.
Stable ground temperature and efficiency
Below the first few metres, ground temperature varies little through the year, while outdoor air is at its coldest exactly when heating demand peaks. A ground-source unit therefore starts each winter day from a warmer, steadier source, and it does not need the defrost cycles an air-source unit goes through. In general terms that can support a higher seasonal coefficient of performance (SCOP) than an air-source unit serving the same building at the same flow temperature.
Treat that as a direction, not a number. The achieved SCOP still depends on the flow temperature the building needs, the pumping energy for the ground loop, the way the borehole field is sized and whether the ground is thermally balanced over the years. A field that takes heat out every winter and puts none back can cool the surrounding ground over time, which is one reason designers look at annual balance, and why a cooling mode that returns heat can help. Use the running-cost calculator to see what SCOP you would need against your own tariffs; a higher SCOP lowers energy cost but does not by itself repay a higher capital cost.
Funding and shared ground loops
The Boiler Upgrade Scheme grant is £7,500 for an air-to-water or ground-source heat pump, and GOV.UK says it can be used for a building used for your business. In England and Wales the installed heat pump capacity must be 45 kW thermal or less for a single heat pump (70 kW thermal for a multi-unit system). MCS and Ofgem guidance allows up to 300 kW thermal collectively where several heat pumps share one ground loop. Applications are made by an MCS-certified installer on the owner’s behalf, and the property must be replacing a fossil-fuel or direct-electric system. Check the current wording with Ofgem before relying on the shared-loop rule for a particular layout.
Above those limits, the grant does not apply. Capital allowances may help: a heating system is an integral feature, special-rate expenditure, so full expensing is not available, but the Annual Investment Allowance (100% up to £1m a year) and the 50% first-year allowance for companies above that may be. Confirm the classification with your accountant. See grants and funding for what is open and closed.
When ground-source earns its premium
There is no rule that makes ground-source the better choice. The case tends to be stronger when several of these are true:
- The site has accessible land or a drilling position, and the ground investigation is favourable.
- Heat demand is high and steady, so extra efficiency is earned every hour of the heating season.
- You own the building and expect to occupy it for a long period, so a longer repayment is acceptable.
- Air-source is hard to site, because of roof loading, noise limits or lack of space for outdoor units.
- There is also a cooling need that the ground loop can serve, or a campus or multi-building site where a shared loop spreads the cost. For larger multi-building schemes see heat networks and ambient loops.
It tends to be weaker for short leases, tight urban sites with no drilling access and buildings with small, intermittent loads. Compare a ground-source quote with an air-source one on the same specification, including whole-life energy cost, not capital alone.