The Short Answer
If you've moved into a new build with a nearly new gas boiler, we'd wait until it needs replacing, unless you want to go all-electric with solar anyway. You may get the £7,500 Boiler Upgrade Scheme grant in England and Wales on a finished new build (a home the developer is still building can't), but the sums are below.
A new home needs much less heat: on our model a 90 sq m semi built 2012 to 2022 needs only the smallest size in our list (3.5kW). Small doesn't mean cheap, though. DESNZ's median for installs under 4kW was £12,000. New homes are moving to low carbon heating by law, and the rules for England and Scotland are below.
Estimate the Saving for Your New Build
Pre-set for a new home on gas, using the median gas use of homes built from 2012 in England and Wales (£680 bill), with the install at the DESNZ median for the under-4kW band, which covers the 3.5kW our model gives a 90 sq m semi built 2012 to 2022. If yours has electric heating, switch the heating type below, and check the grant: gov.uk's new-build exceptions only name homes with a fossil fuel boiler and self-builds.
1. What heats your home today?
Pick whichever your main heating uses.
Add up last year's bills, or use the typical figure for your home below.
3. What size is your home?
We use this to estimate the size of heat pump you'd need.
4. Do you have solar panels?
Free electricity from your roof cuts what the heat pump costs to run.
5. Your options
Both are on to start with. Leave them on unless you know they don't apply.
Your estimated saving
£311a year
Over 15 years that's around £4,665 off your heating bills.
Now: Gas boiler
£680 / year
With heat pump
£369 / year
You save
£311 / year
What about the upfront cost?
- Heat pump install (DESNZ median for this size)
- £12,000
- Less government grant
- -£7,500
- You pay
- £4,500
- A new gas boiler would cost
- ~£2,750
If your boiler needs replacing anyway, the heat pump costs about £1,750 more upfront (before any radiator upgrades), earned back in roughly 5.6 years from running cost savings. That assumes you have the gas supply disconnected, so you stop paying its standing charge (about £108 a year). Keep gas for cooking and it takes longer. It leaves out a heat pump's dearer servicing.
Like the look of £311 a year?
These are estimates. The only way to know your real saving is a free quote from an MCS-certified installer. Takes about 60 seconds, no obligation.
How we worked this out
Energy prices: Ofgem price cap for 1 October to 31 December 2026 (Direct Debit, GB average): gas 7.97p/kWh, electricity 26.32p/kWh. There is no VAT on domestic electricity from 1 October 2026 to 31 March 2027; the gas figure includes 5% VAT. Heat pump tariff blended at 20p/kWh (an estimate for Cosy Octopus, E.ON Next Pumped or EDF Heat Pump Tracker on a heat pump load profile, not a quoted rate). Heating oil 11.31p/kWh (111.52p/litre plus 5% VAT, over 10.35 kWh/litre; BoilerJuice UK average, 23 October 2026). LPG at the price you enter (we start from 75p a litre, our estimate: there's no published average).
Heat pump efficiency: a seasonal efficiency of 3.5. That sits between two measured figures: a median of 2.80 across 291 air source heat pumps in the government's Electrification of Heat trial (installed in 2020 and 2021, whole system), and an average of 4.01 across the 307 systems on heatpumpmonitor.org with a full year of data when we checked in October 2026, a self-selected group of air and ground source systems, mostly high temperature capable R290 units. The break-even with a 90% gas boiler on a standard tariff is a SCOP of about 2.97.
Typical bill ranges: for a 3-bed using 9,500 to 10,300 kWh of heat a year (DESNZ's median and mean gas use for 3 bedrooms in England and Wales, through a 90% boiler): gas £950 to £1,000 (with the standing charge, which the saving assumes you stop paying by having the gas supply disconnected), oil £1,250 to £1,350, LPG £1,200 to £1,300 on our LPG price, direct electric heating £2,500 to £2,700. At these prices a unit of heat from oil costs about 1.5 times as much as from gas, and from LPG about 1.4 times, which is why the saving from switching is bigger.
Solar: A 4kW system in central England generates around 3,800 kWh a year on our estimate (950kWh per kW). On the government's SAP 10.2 self-use formula, a typical 3-bed's heat pump uses about 350 kWh of that a year without a battery, and about 510 kWh with one (8 kWh usable). Most of its demand falls in winter, when panels make least, and the calculator works it out for your bill.
Install costs: DESNZ Boiler Upgrade Scheme statistics (August 2026), median cost of real installs by size: about £11,500 (4-6kW), £12,200 (6-8kW) and £13,900 (10-12kW). For the home size this page starts on, we've used the median for 3.5kW instead: about £12,000. New gas boiler about £2,750 (our estimate). The £7,500 grant is the Boiler Upgrade Scheme (gov.uk) for England and Wales; £9,000 for oil or LPG heating with no mains gas connection until March 2027, which this calculator applies when you choose oil or LPG (if you also have a mains gas connection, take that extra off).
Estimates only. Your actual saving depends on the installer, flow temperatures, your home's heat loss and your electricity tariff. Always get a heat loss survey from an MCS installer for an accurate quote.
Heat Pumps in New Builds: What the Rules Say
England. The Future Homes and Buildings Standards come into force on 24 March 2027. The government's circular says they "will ensure that new homes and non-domestic buildings are built with low carbon heating and high levels of energy efficiency". A building can still be built to the old standards, whenever it's finished, if a building notice, initial notice or full plans were given before 24 March 2027 and work on it starts before 24 March 2028.
Scotland. The New Build Heat Standard applies to all new buildings, and some conversions, where the building warrant was applied for on or after 1 April 2024. The Scottish Government says new homes "must install climate-friendly heating systems instead of oil and gas boilers"; heat networks count as clean heating whatever fuel they use.
This page covers the rules in England and Scotland only, not Wales or Northern Ireland.
Why New Builds Need Less Heat
DESNZ's National Energy Efficiency Data-Framework puts the median gas use of homes built from 2012 at 7,181 kWh a year, against 10,012 kWh for all homes. Those are weather-corrected figures for mid-May 2024 to mid-May 2025, with cooking and hot water included. Through a 90% boiler that's about 6,500 kWh of heat a year, our estimate for a new home and the figure the calculator above starts from.
We ran three new homes through the same heat loss model as our size calculator (standard RdSAP assumptions for their age, a -5.1C design day in the Midlands):
| The home | Heat loss on the coldest day | Heat pump size | DESNZ median for that size band |
|---|---|---|---|
| 3-bed semi built 2012 to 2022, 90 sq m | 2.6kW | 3.5kW | £12,000 |
| 3-bed semi built 2023 or later, 90 sq m | 2.3kW | 3.5kW | £12,000 |
| 4-bed detached built 2012 to 2022, 130 sq m | 4.0kW | 5kW | £11,500 |
That's about 29W per square metre for the 2012 semi, against about 74W for our 1930s semi with unfilled cavities. 3.5kW is the smallest size in our list; the semi built from 2023 needs even less (2.3kW). Only a room-by-room heat loss calculation settles it for your home, and an MCS installer has to do one to size the heat pump.
Does Your New Build Already Have One?
No home in England has had to meet the Future Homes Standard yet, since it isn't in force until 24 March 2027, so don't assume a new build has a heat pump. In Scotland, a home under the New Build Heat Standard has clean heating, which can be a heat network rather than a heat pump. Check the handover pack and the heating controls, and look outside for an outdoor unit. If a heat pump was fitted, ask the developer who installed it and whether it's MCS certified.
Costs: Small Heat Pump, Not a Small Price
A small heat pump doesn't cost proportionally less. DESNZ's 2025/26 median was £12,000 for installs under 4kW (from 239 installs) and £11,500 for 4 to 6kW (our 130 sq m detached example needs 5kW), against £12,200 for 6 to 8kW. These are Boiler Upgrade Scheme installs, so heat pumps fitted in existing homes. A heat pump the developer fits while building is priced into the house, and these figures don't cover it.
A new build's boiler is new, so the calculator's "if your boiler needs replacing anyway" comparison won't usually apply to you. Compare what you'd pay after the grant with the yearly saving instead. With a nearly new gas boiler, what you'd pay after the grant would take about as long as the heat pump lasts to earn back, so we'd wait until the boiler needs replacing, unless you want to go all-electric with solar anyway.
A new build on direct electric heating is different: the saving is bigger. Check the grant first, though, because gov.uk's new-build exceptions only name homes with a fossil fuel boiler and self-builds.
The Grant Catch: BUS Eligibility for New Builds
The Boiler Upgrade Scheme gives £7,500 towards an air source heat pump in England and Wales if you own the home and you're replacing oil, gas, electric or LPG heating. gov.uk says most new builds can't get it, with two exceptions:
- A finished new build with a fossil fuel boiler. If you've moved in, you may be able to get the grant. A home the developer is still building can't.
- A self-build. Eligible if you or the original owner built it, or paid a builder to, and it's never been owned by a business or organisation. You'll need to show your installer proof if you built it yourself.
Running Costs
At the 1 October to 31 December 2026 cap (26.32p a kWh for electricity, 7.97p for gas) and a SCOP of 3.5, on our 6,500 kWh of heat:
- 90% gas boiler: about £580 a year
- Heat pump, standard tariff: about £490 a year
- Heat pump, heat pump tariff: about £370 a year, at our estimate of a 20p blended rate
- Direct electric heating (panel heaters): about £1,710 a year
Those are fuel costs only; with gas you also pay about £108 a year of gas standing charge, which the savings calculator above counts. With less heat to make, the saving against gas is smaller in pounds than in an older home; against direct electric heating it's large.
Questions to Ask About a New Build's Heating
- What heating will the home have, and will it be built to the Future Homes Standard or the older rules?
- If it's a heat pump: what size, what flow temperature it's designed for, and who installed it (is it MCS certified)?
- Where is the outdoor unit, and the hot water cylinder?
- What's on the warranty, and who services it?
Getting Started
If your new build has a gas boiler and you own it, we'd wait until the boiler's due, unless you're going all-electric with solar. Then put your own bill into the calculator above, get quotes and ask each installer for the heat loss calculation. If you're buying off-plan, ask the developer the questions above. Our solar panels and heat pump guide covers adding solar.
Ready to get quotes for your home?
Get free quotes from MCS-certified heat pump installers near you.
More: How the £7,500 heat pump grant works | The gas boiler ban explained | Heat pumps in semi-detached houses
Frequently Asked Questions
New build with a gas boiler? You may still get the grant
Homes still being built can't get the Boiler Upgrade Scheme, but if you've moved into a finished new build with a fossil fuel boiler, you may be able to. Free quotes from MCS-certified installers.