New Build EPC A Rating and Heat Pumps: What Buyers Need to Know Before They Sign

New Build EPC A Rating and Heat Pumps: What Buyers Need to Know Before They Sign

Last updated: 20 May 2026

You've found a new-build you love. The developer tells you it's EPC A-rated, ultra-efficient, and fitted with a heat pump. You sign, you move in, and then the first energy bill arrives — and it's nothing like what the brochure suggested. This scenario is playing out across the UK right now, and it deserves a more honest conversation than most developers are having with buyers.

EPC A ratings on new builds are increasingly the norm rather than the exception, largely because heat pumps are now the default heating solution for developers chasing compliance. But an A on a certificate and a genuinely well-designed, low-running-cost home are not automatically the same thing. Here's what you need to understand before you commit.

Why New Builds Are Almost All Fitted with Heat Pumps Now

The short answer is regulation. Part L of the Building Regulations, tightened substantially in 2021, made it far harder to achieve compliance using a gas boiler. The Future Homes Standard — now mandatory for new builds — takes this further, requiring a dramatic reduction in carbon emissions compared to pre-2021 standards. Heat pumps are, in practice, the primary way developers meet these targets at scale.

This isn't inherently a bad thing. An air source heat pump in a well-insulated new build, sized and commissioned correctly, can be genuinely efficient — delivering three to four units of heat for every unit of electricity consumed, at a Coefficient of Performance (COP) of 3.0 to 4.0. But the phrase "sized and commissioned correctly" is doing a lot of heavy lifting in that sentence.

Recent commentary from CIBSE and other engineering bodies has highlighted that getting the design right matters enormously. Dr Jaydeep Bhadra, writing for PBC Today in 2026, made the point directly: poor heat pump design in new builds is a systemic problem, not an edge case. Installers working at volume, under cost pressure, don't always have the time or incentive to optimise each individual plot.

EPC A Doesn't Mean What You Might Think It Means

EPC ratings are modelled estimates based on standard assumptions about occupancy, thermostat settings, and appliance use. They don't measure what your actual bills will be. The Sustainable Energy Association has argued publicly that bringing measured performance into policy would give consumers a far more accurate picture — and the gap between predicted and real-world performance in new builds can be significant.

What EPC A does tell you is that, on paper, the fabric and heating system should perform well. In a heat-pump-equipped new build, this typically means high levels of wall and roof insulation, double or triple glazing, and a heat pump sized to a heat loss calculation. All of that is genuinely valuable. The problem isn't the rating system per se — it's that buyers are sometimes sold EPC A as a synonym for "cheap to run," when the reality is more nuanced.

Energy prices matter enormously. Electricity in the UK currently sits at around 24–25p/kWh for most households, compared to roughly 6–7p/kWh for gas. Even a heat pump running at a COP of 3.5 produces an effective cost per unit of heat of around 7p/kWh — competitive with a high-efficiency gas boiler, but the margin is thin. A poorly performing heat pump running at a COP of 2.0 costs more to run than gas. This is the uncomfortable arithmetic that brochures don't include.

Common Problems with Developer-Installed Heat Pumps

Developer-installed heat pumps come with a specific set of risks that retrofit installations don't. Volumes are high, margins are squeezed, and the person commissioning your heat pump may be working across thirty identical plots in a week.

The most common new build heat pump problems reported in the UK include:

• Incorrect flow temperature settings. Many developer installs default to higher flow temperatures (55–60°C) that gas boilers use, which destroys heat pump efficiency. The system should run at 35–45°C for underfloor heating and around 45–50°C for radiators to achieve a decent COP.
• Undersized or oversized radiators. Heat pumps work best with larger radiator surfaces. Developers cutting costs often specify standard-sized radiators that force the system to work harder.
• Poor or absent commissioning documentation. Buyers frequently don't receive a full commissioning report, making it impossible to identify whether the system was set up correctly from day one.
• Hot water cylinder issues. Heat pump hot water systems operate differently to gas. Cylinder sizing, legionella control settings, and immersion heater reliance can all add hidden costs.
• Lack of homeowner handover. A heat pump has controls that need to be understood. Many buyers receive no meaningful training and default to settings that cause the system to run inefficiently for years.

You can explore more about how different air source heat pump models compare on performance and suitability for new-build specifications — understanding what you've been installed with is the first step.

Warranty and Developer Responsibility: Who's Actually Liable?

Heat pump warranty in new build situations is more complicated than the manufacturer's literature suggests. Most heat pump brands offer a 2–5 year standard warranty, often extendable to 7–10 years on MCS-registered installations. MCS certification — the Microgeneration Certification Scheme — matters here because it provides a quality assurance framework and is a condition of the manufacturer's extended warranty in most cases. Without it, you may find that warranty claims are disputed.

Developer responsibility sits on top of this. Under NHBC Buildmark or equivalent structural warranties, the developer carries liability for defects in the first two years, with a further eight years of structural cover. But heating system performance issues often fall into a grey area — technically functional but poorly configured doesn't always constitute a defect in warranty terms.

The honest answer is that most buyers discover these issues only when bills arrive. At that point, getting the developer to rectify sub-optimal commissioning is a battle. Your best protection is asking the right questions before you exchange.

Questions to Ask Your Developer Before Exchange

• Who installed the heat pump, and are they MCS-certified?
• What is the heat pump's design COP for this plot?
• What flow temperatures has the system been commissioned at?
• Can I have a copy of the commissioning report at handover?
• What training will you provide on operating the controls?

The Heat Pump New Build vs Retrofit Difference

There's a fundamental distinction between a heat pump installed in a new build and one retrofitted into an older property. In a new build, the entire thermal envelope — insulation, glazing, airtightness — is designed around low-temperature heating from the outset. Radiators are (or should be) oversized. Underfloor heating is common. The heat pump should, in theory, be operating in near-ideal conditions.

In a retrofit, the installer must work around existing pipe runs, radiator sizes, and whatever insulation the house happens to have. Sizing and design require more careful calculation, and the results are more variable.

This means a new build should outperform a retrofit on paper — but only if the developer has actually designed the system properly rather than bolted on a compliant technology to pass regulations. The difference between a thoughtfully designed new-build heat pump system and a tick-box one is measurable in hundreds of pounds per year on your energy bills.

Assumptions: electricity at 24.5p/kWh, gas at 6.8p/kWh, 12,000 kWh annual heat demand for a 3-bedroom new build. Costs are indicative and will vary by tariff and usage.

Grants Available on New Builds — and the Important Caveats

The Boiler Upgrade Scheme (BUS) grant of £7,500 is available to homeowners installing air source heat pumps in England and Wales — but there's a catch that catches many new-build buyers out. The BUS grant is not available on new build properties at first occupation. It's designed for replacing existing heating systems, not for installing into a home where no prior system exists.

This means that if you're buying new, the developer absorbs or passes on the cost of the heat pump without the grant subsidy that a retrofit buyer might access. You can check the full eligibility criteria and what options exist if you're considering adding or upgrading equipment after initial occupation via our Boiler Upgrade Scheme eligibility guide.

The Future Homes Standard mandatory implementation changes the landscape further. Developers can no longer treat heat pump compliance as optional or cost it against a gas alternative — it's the baseline. This may, over time, drive down developer procurement costs and indirectly benefit buyers.

What to Do If You've Already Moved In and Suspect Your System Is Underperforming

If you're already in a new build and your bills are higher than expected, don't assume the heat pump is faulty. The first port of call is the controls. What flow temperature is it set to? Is the hot water being heated by the heat pump or the immersion heater? Is the system running continuous low-temperature heating, or being switched on and off like a boiler?

An independent heat pump health check from an MCS-certified engineer will typically cost £100–£250 and can identify whether your system is correctly commissioned. Many new-build buyers who undergo this find significant room for improvement without any hardware changes whatsoever — just settings adjustments.

If you want to compare what a properly sized and installed system should look like, or if you're advising others buying new, get quotes from vetted MCS-certified installers who can assess your specific situation and provide a benchmark.

Frequently Asked Questions

Does a new build with EPC A automatically qualify for the BUS grant?

No. The Boiler Upgrade Scheme is not available on new build properties at first occupation. It applies to replacing existing heating systems in existing homes. If you add a second heat pump or replace a failed unit after the home is occupied, eligibility may arise, but this is not the norm. Check current rules via official guidance before assuming any grant applies.

Can I request a different heating system on a new build, instead of the developer's default heat pump?

In theory, some developers will accommodate requests during the early reservation stage, particularly on bespoke or self-build plots. In practice, volume housebuilders work to standardised specs and switching out the heating system is rarely permitted. The Future Homes Standard effectively mandates heat pumps as the default outcome anyway, so the scope for alternatives is narrowing further.

Who is responsible if my developer-installed heat pump breaks down within the first year?

Within the first two years, the developer carries primary liability under NHBC Buildmark and equivalent warranties for defects. The heat pump manufacturer's warranty runs in parallel. For a genuine mechanical failure, the manufacturer's warranty (via MCS registration) is usually the more direct route. For commissioning-related underperformance — which isn't technically a defect — the developer's liability is less clear-cut and often requires formal written complaint escalation.

Is it worth paying for an independent heat pump survey before completing on a new build?

Yes, if the developer will allow access. A snagging survey that specifically covers the heating system — flow temperatures, cylinder sizing, commissioning documentation — can identify issues before you complete. Most standard snagging companies don't go into this level of detail on heat pumps, so look for one with specific low-carbon heating experience, or ask an MCS-certified engineer to accompany the snagging visit.

Get an Independent Assessment of Your New Build Heat Pump

Whether you're buying off-plan, negotiating on a completed plot, or already in and wondering why your bills don't match the EPC, an independent view from a qualified installer is the most valuable thing you can invest in. Our network of MCS-certified engineers can assess, optimise, and — where necessary — reconfigure developer-installed systems to perform as they should.

quotes">Compare quotes from MCS-certified heat pump specialists and find out what your new build system is actually capable of.