New Build EPC A Rating and Heat Pumps: What the Developer Fitted, What It Costs You to Run

New Build EPC A Rating and Heat Pumps: What the Developer Fitted, What It Costs You to Run

Last updated: 19 July 2026

One buyer on a new estate near Bicester opened her first winter energy bill and found she owed £310 for a single month — despite living in a supposedly A-rated home with a shiny new air source heat pump on the side wall. She'd been told the property would be "cheaper to run than anything on the market". The number on the bill said otherwise. Her mistake wasn't buying a new build with a heat pump. It was assuming the developer had commissioned it properly and shown her how to use it.

This is the tension at the heart of buying a modern new-build home in 2026. On paper, an EPC A rating plus a heat pump is exactly what the government wants your house to be. In practice, the gap between the theoretical performance on the energy certificate and the money leaving your bank account each month can be startling — and it usually comes down to how the system was installed, sized and explained.

Why almost every new build now comes with a heat pump

The direction of travel is fixed. The Future Homes Standard heat pump requirement effectively ends gas boilers in new-build homes across England, with the standard being rolled out through 2026. New properties are expected to produce around 75–80% fewer carbon emissions than one built to the old 2013 rules, and the practical way developers hit that target is a well-insulated fabric plus a low-carbon heating system — in the vast majority of cases, an air source heat pump.

Barratt Redrow, Britain's largest housebuilder, delivered completions at the upper end of its guidance this year, and heat pumps are now standard fit across large swathes of that output. So if you're buying new, the question is rarely "will it have a heat pump?" It's "was the heat pump done well?"

The EPC A rating tells you less than you think

An EPC A rating is a modelled figure. It's produced by software that assumes standard occupancy patterns, standard thermostat settings and a heat pump running at its design efficiency. It does not measure your actual home, your actual habits, or whether the installer got the flow temperature right on the day.

A heat pump is only cheap to run when it operates at a low flow temperature — ideally 35–45°C. Push it to 55°C because the radiators are undersized or the system was rushed, and its efficiency (the SCOP) drops sharply. At the electricity price cap of around 27p/kWh in mid-2026, that difference is real money.

The honest answer is that the label on the wall matters far less than who set the machine up and whether you're on the right electricity tariff. A specialist heat pump tariff can cut your bill by hundreds of pounds a year on the exact same hardware.

New build heat pump problems: the issues buyers actually report

The most common new build heat pump problems in the UK aren't dramatic failures. They're small setup faults that quietly cost you money:

• Flow temperature left too high. Commissioning engineers under time pressure sometimes default to 50–55°C to guarantee the home heats quickly on handover day, then never dial it back.
• Weather compensation switched off. This feature adjusts output to the outside temperature and is one of the biggest efficiency levers. It's often disabled or unconfigured.
• Undersized radiators or underfloor loops. If the emitters are too small, the pump has to run hotter to compensate.
• No handover explanation. Buyers get keys and a folder, but nobody shows them how the controls work — so they run it like a gas boiler, turning it off and on.

None of these are inherent to heat pumps. They're symptoms of volume housebuilding where heating is one line item among hundreds. When a developer-installed heat pump review goes badly, it's almost always a commissioning story, not a technology story.

New build versus retrofit: why the same appliance behaves differently

The core difference between a new build and a retrofit heat pump is the building around it. A new home is built airtight and heavily insulated, so its heat demand is low and the pump can run at gentle, efficient flow temperatures. A retrofit into a 1930s semi has to fight draughts and solid walls, often requiring radiator upgrades to work well.

That makes the new-build heat pump the easier case, in theory — the fabric is already doing half the work. Which is exactly why a badly commissioned new-build system is so frustrating: the house is capable of running cheaply, and it's the setup, not the structure, holding it back. If you're comparing systems or want to understand the technology itself, our guide to air source heat pumps breaks down how they perform in different homes.

Warranty and developer responsibility: who fixes it when it goes wrong

This is where new-build buyers get confused. There are usually two overlapping protections:

• The manufacturer's warranty on the heat pump itself — commonly 5 to 7 years, sometimes extendable to 10.
• The developer's warranty / NHBC-style cover on the home, typically 2 years of full builder liability then structural cover beyond.

On heat pump warranty and developer responsibility in a new build, the key point is that for the first two years, defects — including a badly commissioned or wrongly sized system — are generally the developer's problem to put right. Report issues in writing early. Manufacturer warranties almost always carry a condition that catches people out: annual servicing protects your warranty and efficiency, and skipping it can invalidate a claim later.

Crucially, insist that the installer holds MCS certification. MCS is the quality standard that governs how heat pumps are designed and installed in the UK. It's not bureaucratic box-ticking — an MCS-certified installation means the heat loss was calculated properly and the emitters were sized to match, which is precisely the step that goes wrong on rushed sites. It's also a condition of the grant support that funds retrofits.

What about the £7,500 grant — do new build buyers get it?

No. The £7,500 Boiler Upgrade Scheme grant is for replacing fossil-fuel heating in existing homes, not new builds where the developer already installs the pump as standard. The upside is that the cost of the heat pump is already baked into your purchase price rather than being an extra bill.

Where the £7,500 grant becomes relevant is if you later move from your new build to an older property, or if you're weighing new build against buying and retrofitting an existing home — in which case the grant meaningfully changes the maths.

Frequently asked questions

My new build heat pump seems expensive to run — can I get the developer to fix it?

Within the first two years, yes, in most cases. Ask the developer to arrange a recommissioning visit to check flow temperature, weather compensation and radiator sizing. Put the request in writing and reference your warranty. If they're unresponsive, an independent MCS installer can assess the setup and quote for corrections.

Do I need to service a heat pump on a brand-new house?

Yes. Even a new system needs an annual service to keep the manufacturer's warranty valid and maintain efficiency. Some developers include the first year's service; check your handover pack.

Is a heat pump in a new build really cheaper than a gas boiler would have been?

In a well-insulated new build running at a low flow temperature and on a heat pump tariff, yes — often comparable to or cheaper than gas. Run it poorly on the standard cap and it can cost more. The setup and tariff decide the outcome.

Can I switch to a specialist heat pump electricity tariff straight away?

Usually yes, once you have a smart meter installed. Several suppliers offer dedicated heat pump tariffs at well below the standard cap, which is often the single fastest way to reduce your bill on an existing installation.

Getting a second opinion on your new-build system

If your bills don't match the promise on the EPC, the fault is almost always fixable — a flow temperature tweak, a tariff switch, or a proper commissioning check. The trouble is knowing whether you're getting straight advice. An independent, MCS-certified installer can assess how your system was set up and tell you exactly what's costing you money. Compare quotes from vetted MCS installers near you and get a clear read on whether your new-build heat pump is performing as it should.