Air-Source Heat Pumps (Commercial): Commercial heat pump grants

Why air-source is the natural starting point when you are chasing commercial heat pump funding

For most UK organisations looking at low-carbon heat, the first question is not which technology, it is what it will cost and what funding exists to close the gap. Commercial air-source heat pumps are the most common answer because they carry the lowest capital, the fastest install and the least disruption of any heat pump route, with no ground works or boreholes to dig. That keeps the headline number down before any grant is applied, which matters because the cheapest project to fund is the one that needs the smallest cheque in the first place. The catch that catches everyone out is the same one we lead with on every page: the headline £7,500 Boiler Upgrade Scheme is domestic-only and does not touch a commercial building. The funding routes that do apply, the Public Sector Decarbonisation Scheme, the Industrial Energy Transformation Fund, the Green Heat Network Fund and capital tax relief, work very differently, and an air-source project is usually the easiest of all the heat pump types to slot into them.

Air-source suits a huge spread of buildings, offices, care homes, schools, hotels, leisure centres and light industrial units, which is exactly the population most of the named grant schemes are aimed at. Because the technology is mature and the design well understood, the business case is straightforward to model and therefore straightforward to defend in a competitive grant application. When a Salix Public Sector Decarbonisation Scheme bid or a full-expensing tax claim rests on credible numbers, an air-source scheme designed to recognised standards gives you the cleanest evidence base to build the funding case on, which is the whole point of working with a specialist rather than taking an off-the-shelf quote.

It also helps that air-source addresses the pressures most commercial buyers are actually feeling. Gas prices remain volatile and the Climate Change Levy adds cost on top, so heating budgets swing unpredictably from one year to the next; an electrified heat pump on a sensible tariff replaces that uncertainty with something far more controllable. Ageing boiler plant nearing failure forces the decision anyway, and landlords face MEES and EPC pressure that a heat pump helps answer. The recurring worry is running cost, because electricity is currently three to four times the unit price of gas, but that is precisely why the design matters: at an SCOP of 3.0 to 4.0 the heat pump delivers three to four units of heat per unit of electricity, which offsets most of that price gap, and the funding routes reduce the capital that has to be recovered in the first place. Many decision-makers have been burned by over-optimistic quotes before, so we model from real consumption data rather than a sales estimate, which is also what a competitive grant application demands.

What a typical install looks like and how we size it

A commercial air-source system usually lands in the 40 to 500 kW thermal band, delivered as anything from a single unit up to a cascaded bank of 4 to 12 modular units sitting in an external louvred compound or on a roof plant deck taking around 20 to 200 square metres of plant area. A system of that size delivers in the region of 80,000 to 1,000,000 kWh of heat a year and removes roughly 15 to 180 tonnes of CO2 annually. We never size from floor area. Sizing comes from a proper heat-loss survey and at least 12 months of your gas or oil consumption, because the funding case lives or dies on real demand data, not a rule of thumb. The single biggest lever on performance is flow temperature: every degree we can shave off lifts the SCOP, so we design for 45 to 55C wherever the emitters allow, targeting an SCOP of 3.0 to 4.0.

The modular nature of cascaded air-source is part of why it is so adaptable. The same design approach scales from a single office block to a large mixed-use site simply by adding units, and a cascade also gives useful resilience because the load is shared across several compressors rather than resting on one. Where the emitters were originally sized for a 70 to 80C gas boiler, we look at whether selective upgrades let the system run at 50 to 55C rather than assuming a full strip-out, since the emitter decision has a direct bearing on both the SCOP and the capital the funding has to cover. Plant-room space, external unit siting and acoustic limits all shape the layout, so we resolve those constraints at design stage rather than discovering them on site.

Costs, payback and tax relief

A commercial air-source project typically runs £60,000 to £600,000 depending on building size, the emitter upgrades required and any electrical supply work, with a simple payback near 8 years before any grant is taken into account. Grant funding shortens that materially, and so does the tax position. Heat-pump plant of this kind qualifies as plant and machinery, so full expensing lets a company paying UK corporation tax claim a 100% first-year deduction on new, unused qualifying kit, worth up to 25p of tax saved per pound spent at the 25% rate, with full expensing made permanent from April 2026. Sole traders and partnerships use the Annual Investment Allowance instead, up to £1m of qualifying spend at 100%. Some ancillary wiring may fall outside full expensing but still qualifies for AIA, and treatment should always be confirmed with your accountant. Our cost guide works through the installed cost and the tax treatment side by side.

Funding routes in detail

Which named scheme fits depends on who you are. Public-sector bodies, NHS trusts, schools, colleges, universities, local authorities and emergency services, apply to the Public Sector Decarbonisation Scheme run by Salix Finance for DESNZ, which funds the cost over and above a like-for-like fossil-fuel replacement and takes a whole-building view; it runs in competitive windows with firm completion deadlines and is for public bodies only, not private commercial buildings. Eligible industrial sites with a qualifying SIC code can look to the Industrial Energy Transformation Fund, though that is aimed at large-scale process heat rather than ordinary office heating. Multi-building campuses can consider the Green Heat Network Fund.

Every business, public or private, can use the capital allowances route described above, which for many private commercial buildings is the single most valuable lever available since there is no headline commercial grant equivalent to the domestic Boiler Upgrade Scheme. That is the gap we exist to fill: rather than leaving you to discover the hard way that the £7,500 grant does not apply, we map which of these routes you actually qualify for and build the application around the project rather than the other way round. The detail, including the recognised authority guidance for each scheme, sits on our grants and funding page.

Compliance and sector considerations

For systems up to 45 kWth, MCS certification or a recognised commercial equivalent is required to access most grant routes, and we hold MCS 025 installer competency. Above 45 kWth we design to CIBSE and BSRIA standards with performance rated to BS EN 14511 (rated COP) and BS EN 14825 (SCOP) so the figures in your funding bid are directly comparable to any compliant supplier. Most air-source installs fall under permitted development, but they are subject to size, siting and noise limits, so a BS 4142 acoustic assessment is commonly required to show the external units will not disturb neighbours; listed buildings and conservation areas need consent.

All refrigerant work is carried out by F-Gas certified engineers under the UK F-Gas Regulation, and the refrigerant phase-down of high-GWP gases is steering modern units toward lower-GWP R32 (A2L) and, for higher duties, natural refrigerants. Systems are designed to BS EN 378 for safety and environmental compliance. The other early conversation is electrical: large units add real load, so we confirm DNO supply capacity at feasibility because a supply upgrade can be the longest-lead item in the whole programme, and on a constrained site we look at phasing, a hybrid design or demand management to stay within the available capacity. Where public-sector or enterprise procurement is involved, the BS EN ISO 9001, 14001 and 45001 management standards are commonly required as well.

How we approach this kind of project

We start with your half-hourly meter data and 12 months of fuel consumption, because the funding case has to be built on what the building genuinely uses, not an optimistic estimate. We size for self-consumption and the lowest viable flow temperature to maximise SCOP, survey the existing emitters and pipework so you do not pay for a strip-out you do not need, and check the roof or plant compound and any asbestos before we quote a fixed price rather than on the day of install. We get the G99 grid application and any DNO supply enquiry in early so the long-lead item is not the thing that derails the timetable, which matters even more when a grant scheme carries a fixed completion deadline. You receive a fixed-price proposal with the running cost and carbon modelled from your own data at current and forecast prices, an insurance-backed warranty, and a clear view of which grant or tax route the scheme is being built to qualify for. We would rather lose a job to honest maths than win it on a number we cannot stand behind, and you are welcome to stress-test the model or get a second opinion.

An illustrative example

As an illustrative composite based on typical UK projects, and not a real named client: a 70-bed care home running a pair of ageing gas boilers nearing failure, with a year-round heating and hot-water demand and rising bills, wanted to cut carbon for its net-zero pledge and stabilise running costs without a winter shutdown. The design was a 180 kW cascaded air-source heat pump (6 modular units) with selective emitter upgrades and the existing boiler retained for peak backup, delivering in the region of 360,000 kWh of heat a year at an SCOP of around 3.6. On-site combustion fell roughly 85%, saving around 55 tonnes of CO2 a year, and the indicative saving was about £22,000 against the prior gas cost for a payback near 7.5 years. The install was timed around the operating calendar in autumn with the old boilers kept live through commissioning, so the home was never without heat, and full expensing delivered the 25% first-year tax relief. The figures are illustrative and depend on your building, tariff and the funding you qualify for.

If your building has high-temperature emitters or you would rather phase the change, our pages on hybrid and boiler-replacement retrofit and commercial ground-source heat pumps set out the alternatives. To see the numbers, read the cost guide and the grants and funding routes, browse the FAQs, then request a free feasibility built from your meter data.