New Build EPC A Rating and Heat Pumps: Making the Most of What Your Developer Has Already Installed

New Build EPC A Rating and Heat Pumps: Making the Most of What Your Developer Has Already Installed

Last updated: 27 May 2026

You've just picked up the keys to your new build. The developer's sales brochure mentioned something about an air source heat pump and an EPC A rating, and at the time it sounded like a tick in the right box. Now you're actually living there, the heating feels different from what you grew up with, your energy bills aren't quite what you expected, and you're wondering whether what's been installed is actually right for your home — or whether you've inherited someone else's compromise. You're not alone. This is one of the most common situations we hear about from new-build buyers in 2026.

Why New Builds Are Now Almost Always Heat Pump Homes

The shift didn't happen overnight, but it has accelerated sharply. Since the tightening of Part L of the Building Regulations in 2021, developers have faced increasingly demanding fabric efficiency targets, and the EPC A rating — once genuinely rare — has become the expected baseline for new residential construction. Heat pumps are not the only route to achieving it, but for the vast majority of volume housebuilders, they are the most straightforward one.

With the Future Homes Standard mandatory from 2026, new builds must comply with rules that effectively rule out gas boilers as the primary heating system in virtually all new residential properties. That decision is now made. If you've bought or are buying a new build, you will almost certainly have a heat pump, or will need to plan for one.

What that means in practice is that the conversation has shifted. It's no longer whether to get a heat pump in a new build — it's whether the one you have (or are about to have) is sized correctly, configured properly, and supported by a warranty arrangement that actually protects you.

What an EPC A Rating Actually Tells You — and What It Doesn't

An EPC A rating means the property, as modelled, has a very high predicted energy efficiency score. In new builds, this is calculated using the Standard Assessment Procedure (SAP), which rewards good insulation, low air permeability, triple glazing, and low-carbon heating systems. A heat pump, combined with a well-insulated fabric, scores extremely well under SAP modelling.

Here's the honest answer, though: a SAP-modelled EPC A does not guarantee your bills will be low. The model assumes standardised occupancy patterns, thermostat settings, and weather conditions. Real-world running costs depend heavily on how the heat pump is commissioned, what flow temperatures it's running at, and how you as the occupant use the system.

A developer can achieve an EPC A by installing a heat pump and moving on. Whether that heat pump is optimised for your specific plot, your hot water demand, or your daily routine is a separate question entirely — and one that EPC documentation simply doesn't address.

The Heat Pump New Build vs Retrofit Difference: Why New Builds Have the Advantage

One of the more important distinctions in the heat pump world is the difference between a heat pump new build vs retrofit installation. In a retrofit scenario, the installer is working around an existing system — often with radiators sized for a gas boiler's higher flow temperatures, draughty floors, or awkward pipe runs. Compromises are sometimes unavoidable.

New builds have none of those constraints. The fabric is designed from the outset for low-temperature heating. Radiators are oversized to compensate for a heat pump's lower flow temperatures. Underfloor heating, which is ideal for heat pump operation, is straightforward to install before screeding. In theory, a new build with a correctly installed heat pump should run more efficiently than almost any retrofit equivalent.

The key phrase is "correctly installed." The difference between a well-commissioned new build heat pump and a poorly configured one can be significant — both in comfort and in the coefficient of performance (CoP) the system actually achieves day-to-day.

Typical New Build Heat Pump Specifications

Electricity in the UK sits at around 24–25p/kWh on standard tariffs in early 2026. At a CoP of 3.0, that means each unit of heat costs you roughly 8–8.3p to produce. Gas at 6–7p/kWh with a boiler efficiency of 88–90% delivers heat at roughly 6.7–8p/kWh. The economics are closer than the marketing suggests — but time-of-use tariffs such as Octopus Agile or Economy 7 can shift them materially in the heat pump's favour if your system is configured to take advantage of overnight cheap rates.

New Build Heat Pump Problems: What UK Buyers Are Actually Experiencing

New build heat pump problems in the UK tend to cluster around a handful of recurring themes. Understanding them helps you know what to look for — and what to push back on with your developer.

Commissioning and Controls Settings

The single most common issue is incorrect flow temperature settings. Many developer-installed heat pumps are left at flow temperatures of 50–55°C from installation — settings more appropriate for an older radiator system than a modern new build. A well-insulated new build with correctly sized emitters should run comfortably at 35–45°C flow temperature, which is where heat pumps achieve their highest efficiency. If nobody has walked you through the controls or adjusted the weather compensation curve, the system may be working much harder than it needs to.

Cylinder and Hot Water Configuration

Hot water is where heat pumps take their biggest efficiency hit. Raising a cylinder to 60°C for Legionella prevention pulls the CoP down sharply. Some developer installations schedule this daily; many heat pump engineers recommend weekly cycles instead, with the cylinder set to 45–48°C for day-to-day use. If your hot water is costing more than expected, this is the first thing to review.

Oversized or Undersized Units

Volume developers sometimes specify heat pumps from a limited approved supplier list, applying a standard size across a house type regardless of plot-specific factors — orientation, shading, or the number of external walls. An oversized heat pump will short-cycle, reducing efficiency and increasing wear. Undersized units will struggle in cold snaps. If your home was part of a large development and you're consistently uncomfortable, it's worth commissioning an independent heat loss calculation to verify whether the installed unit is appropriate.

Developer Responsibility, Warranties, and Who to Call When Things Go Wrong

A developer installed heat pump review from a UK buyer typically runs into the same wall: the developer points to the heat pump manufacturer, the manufacturer points to the installer, and the installer points to the commissioning engineer. Understanding the chain matters.

Under NHBC Buildmark and similar structural warranties, the fabric of the building is covered for ten years. The heat pump itself falls under the manufacturer's product warranty — typically five to seven years depending on the brand, sometimes extendable to ten. However, the manufacturer's warranty is usually conditional on the system having been installed and commissioned by a qualified engineer, with proper documentation provided at handover.

This is where MCS certification becomes important. MCS (Microgeneration Certification Scheme) is the industry quality standard for heat pump installations. An MCS-certified installation provides assurance that the system was designed, installed, and commissioned to a defined standard — and it's the minimum requirement for any installation to be eligible for government support. If your developer-installed heat pump was not MCS certified at installation, you may face complications both with warranty claims and with any future grant applications. Always request the MCS certificate and commissioning documentation at handover — it should be part of your property pack.

Heat pump warranty in new builds and developer responsibility is a grey area that has caught out a number of buyers. The NHBC's guidance acknowledges that mechanical and electrical systems are generally the developer's responsibility for the first two years — so if something goes wrong in that window, pursue the developer directly rather than the manufacturer first.

Can You Still Claim the BUS Grant on a New Build?

The short answer is no — not for the property where the heat pump has already been installed by the developer. The Boiler Upgrade Scheme's £7,500 grant for air source heat pumps is available for homes replacing a fossil fuel heating system, and new builds do not qualify because there is no existing system being replaced.

However, if you later move to a different property — one built before 2023 with a gas or oil boiler — the Boiler Upgrade Scheme grant would apply to a new heat pump installation in that home. For buyers of new builds, the relevant financial consideration is not the grant but the running cost optimisation: getting the most out of a system that is already there.

If you're a developer or housing association considering heat pump specifications for a pipeline of new properties, the BUS grant does not apply to your new-build output, but there are separate mechanisms under the Social Housing Decarbonisation Fund and Homes England programmes worth exploring.

When an Independent Review Makes Financial Sense

If you moved into your new build in the last twelve months and haven't had the heat pump settings reviewed by an independent engineer, it's likely worth arranging. The cost of a commissioning review — typically £150–300 from a specialist — frequently pays back within a single heating season through improved efficiency. Look for an engineer who holds MCS certification and has specific experience with the brand installed in your home; the controls interfaces differ significantly between manufacturers and general plumbers are rarely the right choice here.

For buyers who are still in the process of selecting a new build plot or negotiating with developers, it is worth asking explicitly which heat pump model will be installed, requesting the heat loss calculation for your specific plot, and confirming that MCS commissioning will be completed before handover. These are reasonable asks and a competent developer should have no difficulty providing them.

If you want to compare air source heat pump models to understand whether what's been specified for your new build is appropriate for its size and heat demand, our comparison tool gives you real specification data across the main brands used in UK housebuilding.

What to Do If You're Not Happy With the System You've Inherited

Start with documentation. Request all commissioning records, the MCS certificate, the heat loss calculation, and the manufacturer's warranty registration confirmation. If these haven't been provided, write to the developer formally — this creates a paper trail that matters if you later need to escalate.

Have the flow temperatures and weather compensation settings checked. This costs very little and frequently resolves the most common complaints about comfort and bills.

If the system has a fundamental sizing or specification problem, seek independent written confirmation from an MCS engineer and pursue the developer under their two-year defects obligation. Don't accept verbal reassurances.

And if you're at the stage of comparing quotes for a replacement or supplementary system — or you want a second opinion on whether what's installed is fit for purpose — get quotes from MCS-certified installers here who can assess your specific home and system without any obligation to the original developer.

Frequently Asked Questions

My new build has an EPC A rating but my bills seem high — is the heat pump to blame?

Not necessarily, but the heat pump configuration is the first thing to check. Flow temperatures set too high and daily Legionella cycles are the most common culprits. Have a qualified engineer review the settings before drawing conclusions about the hardware itself.

What warranty should I have received with my developer-installed heat pump?

Most major brands installed in new builds — Vaillant, Daikin, Mitsubishi, Samsung — offer five-year standard warranties, often extendable to seven or ten years if registered. Crucially, the warranty is conditional on MCS-compliant commissioning. Request the registration confirmation and MCS certificate from your developer if they weren't in your handover pack.

Does the Future Homes Standard affect me if I've already bought a new build?

The Future Homes Standard applies to new planning applications and construction going forward. If you've already completed on a new build, the standard affects your home's specification only if construction fell under its scope. For buyers of completed homes, the immediate priority is operating the installed system efficiently, not compliance with future-facing regulation.

Can I replace a developer-installed heat pump with a different brand or model if I'm not satisfied?

Yes, technically — but be cautious about doing so within the first two years while the developer's defects liability period is active. Replacing the system could complicate any defect claims. If the heat pump has a genuine fault, pursue the developer first. If you simply want a different specification after that window, an MCS-certified installer can design a replacement system to the same new-build standards.

Ready to Get a Second Opinion or Compare What You've Got?

Whether you're a new-build buyer trying to understand an unfamiliar system, a developer specifying heat pumps across a pipeline of plots, or simply trying to work out whether you're getting what you paid for — independent, qualified advice makes a material difference. Our network of MCS-certified engineers covers the whole of the UK and can assess your property without any obligation to your original developer or their approved supplier list.

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