Heat Pump vs New Boiler: What Each Does to an EPC Score

Key takeaway: replacing an old non-condensing boiler typically adds 5-15 SAP points for £2,000-£3,500. An air source heat pump often adds 10-20, but on today’s cost-based SAP the exact uplift varies with the model’s electricity-price assumptions, an honest per-property answer beats any blanket promise. Two things tilt the long game toward the heat pump: the £7,500 Boiler Upgrade Scheme, and the reformed EPC’s dedicated heating-system metric, targeted from October 2026 subject to the regulations.

Heating is where the biggest single-system EPC gains live, typically 15-25% of the score’s weighting, and it is also where the current methodology behaves most oddly. This guide gives the straight version: what each option does to a SAP score today, why heat pumps can score less than their efficiency suggests under the current rules, what the confirmed 2026 reform changes, and how the grant arithmetic falls.

What a new boiler does to a SAP score today

Replacing an old non-condensing boiler with a modern condensing model typically adds 5-15 points for £2,000-£3,500 installed, roughly £200-£400 per point, which puts it mid-table on value. Pair it with full controls, programmer, room thermostat and TRVs, at £150-£500 for typically +2-5 points, and the combined heating package is one of the strongest moves on most D- and E-rated certificates. Our heating and controls hub covers the sequencing.

Two caveats keep the numbers honest. If you already have a reasonably modern condensing boiler, a like-for-like swap adds very little, the points came with the condensing technology, not the newness. And under RdSAP 10, in force since 15 June 2025, the assessor scores the actual boiler from documented model data: keep the make, model and serial number or the manual, because an unevidenced efficient boiler defaults to pessimistic age-band assumptions that throw the gain away.

What a heat pump does to a SAP score today

An air source heat pump typically adds 10-20 points, usually the largest single-system uplift available, and under RdSAP 10 the smart controls and any battery storage that come with it are now recorded too. But the honest version carries a caveat the sales brochures skip: on the current methodology, the size of the uplift varies from property to property with the electricity-price assumptions inside the model, and it should be confirmed for your home before you commit, not assumed from a national range. The measure’s full profile, grant conditions, consent and evidence detail, sits in our heat pump improvement hub.

Why the variance exists is worth understanding, because it is the most misunderstood corner of the whole scoring system.

The cost-metric quirk, explained honestly

Today’s domestic EPC score is built on one metric: modelled running cost per square metre. A heat pump turns each unit of electricity into roughly three units of heat, which is a genuine efficiency revolution, but electricity costs several times more per unit than mains gas, and the model prices that in. The efficiency gain and the tariff penalty pull against each other, so the net scored improvement depends on the cost assumptions in the calculation and on the property itself. A well-insulated home running low flow temperatures captures more of the efficiency; a leaky one captures less.

The result: heat pumps can score more modestly under the current cost-based SAP than their engineering deserves, and occasionally the numbers surprise in either direction. That is a defect of the metric, not the technology, and the government has, in effect, agreed. For how the underlying model works, see our plain-English guide to how EPC points are calculated.

Three questions cut through the uncertainty before any contract is signed. What does the recommendation report on your current certificate estimate for a heat pump, for this specific property? Will the system be designed to run at low flow temperatures, with the radiators sized to match? And has anyone modelled the score impact under the current methodology rather than quoted a national range? An installer who cannot answer all three is guessing with your points.

The reform that changes the answer, dated and exact

In its partial government response on EPC reform (March 2026), published 9 March 2026, the government confirmed that domestic EPCs will move from the single cost metric to four headline metrics, energy cost, fabric performance, heating system and smart readiness, produced with the Home Energy Model in place of SAP and RdSAP. New-style certificates are targeted from October 2026, subject to the 2026 regulations; industry reporting suggests the date could slip, so check gov.uk before planning around it.

For this comparison, the key phrase is heating system. Once the heating technology is assessed on its own metric rather than buried in a blended running-cost figure, a heat pump’s position strengthens structurally, while an ageing gas boiler’s weakens. The confirmed landlord standard points the same way: on 21 January 2026 the government confirmed that privately rented homes in England and Wales must meet EPC C by 1 October 2030, measured across two of the reformed metrics, fabric performance plus either heating system or smart readiness, with a proposed £10,000 cost cap. That is confirmed policy, not yet enacted law; secondary legislation is reported as targeted for 2027.

The money: grant, VAT and net cost

	New condensing boiler	Air source heat pump
Typical installed cost	£2,000-£3,500	£8,000-£15,000
Grant support	none	£7,500 Boiler Upgrade Scheme (England and Wales, landlords eligible)
Typical net cost	£2,000-£3,500	commonly £500-£7,500 after the grant
Typical SAP points today	+5-15 (replacing non-condensing)	+10-20, property-dependent
Position under the reformed metrics	weaker on the heating-system metric over time	clearly strong on the heating-system metric
Evidence to keep for RdSAP 10	make, model and serial number, or the manual	MCS certificate

£7,500, the Boiler Upgrade Scheme grant toward an air or ground source heat pump in England and Wales. It routinely brings the net cost of a heat pump inside the price of a premium boiler swap.

The Boiler Upgrade Scheme requires an MCS-certified installer and a valid EPC with no outstanding loft or cavity wall insulation recommendations (unless technically unsuitable), fabric first is literally a grant condition, which is why clearing the insulation measures comes before the heating decision in every plan we build. Funding has been allocated through 2029/30 under the Warm Homes Plan, and a temporary higher grant for oil and LPG-heated homes was announced in 2026, treat £7,500 as the dependable figure and confirm the current uplift value on gov.uk. Heat pumps and heating controls also qualify for the 0% VAT rate on energy-saving materials until 31 March 2027.

Which should you choose?

Five honest scenarios cover most owners:

1. Old non-condensing boiler, tight budget, chasing C. The boiler-plus-controls package is strong value at £200-£400 per point and needs no grant paperwork. Do it with the model number documented.
2. Off the gas grid on oil or LPG. The heat pump case is at its best: high existing fuel costs, the £7,500 grant, and the announced oil/LPG uplift to check on gov.uk.
3. Landlord planning past 2030. The confirmed dual-metric standard makes the heating-system metric one of your two scoring routes. A heat pump fitted once, with the fabric done first, beats a boiler that may need justifying again within its own lifetime.
4. Electric-heated flat with no wet system. Neither option fits neatly. Installing radiators for either a boiler or a heat pump is a bigger project than the certificate alone justifies, and leaseholders face freeholder-consent constraints, so the realistic levers are high-retention storage heaters, proper controls, a cylinder jacket and LEDs, with heat pump feasibility assessed case by case.
5. Already on a modern condensing boiler. Neither move earns its keep on points alone. Spend on fabric and controls instead, the site-wide ranking of every EPC measure by cost per point shows where the cheap points actually sit.

Common questions

Can a heat pump ever leave my EPC score flat?

It can gain less than expected, yes. Under the current cost-based SAP the modelled saving depends on electricity-price assumptions and on how efficiently the property lets the pump run, so the uplift ranges from transformative to modest. The direction of travel is friendlier: the reformed heating-system metric, targeted from October 2026 subject to regulations, assesses the technology directly. Get the per-property modelling before you sign anything, and if you improve, make sure the gain is captured at re-assessment.

Do outstanding insulation recommendations block the £7,500 grant?

Yes. Boiler Upgrade Scheme eligibility requires a valid EPC with no outstanding loft or cavity wall insulation recommendations, unless they are technically unsuitable for the property. In practice that means the cheap fabric measures come first, the EPC is refreshed if needed, and the heat pump application follows, a sequence that also happens to be the cheapest way to buy points. Typical prices for each step are on our guide to real-world pricing for every measure, with more answers among frequently asked EPC questions.

Should I wait for the Home Energy Model EPCs before deciding?

Waiting buys less than it appears to. Your existing certificate keeps its ten-year validity through the change, the measures that score well are the same under both regimes, efficient heating and controls feed the heating and smart metrics either way, and the reformed certificates are only targeted from October 2026, subject to regulations that may slip. Meanwhile the Boiler Upgrade Scheme is open now, the 0% VAT window closes 31 March 2027, and installer demand will only tighten as the confirmed 2030 landlord standard approaches. Decide on your property’s numbers, not the calendar.

Get the per-property answer before you spend

The generic comparison ends in a tie that helps nobody: boilers win on upfront cost today, heat pumps win on grant support and the reformed metrics. Your property breaks the tie. Request your quote and we will put numbers on both routes, points, net cost, and position under the rules as they stand and as they are confirmed to change.