I’ve been writing about UK property and energy policy for long enough to notice a pattern: most buyers still choose a home based on how it looks, not how it performs. That’s a problem, because the running costs and carbon footprint of a house are determined almost entirely by things you can’t see — the insulation in the walls, the type of heating system, the airtightness of the structure. With the Future Homes Standard coming into force in March 2027, every new home built after that date will have to meet a much higher bar. But if you’re buying now, or looking at a new-build completed before the deadline, you need to know what to look for yourself. Here’s what you actually need to know.
That gap in heating costs — hundreds of pounds a year — is the single biggest reason to care about sustainability when you’re choosing a house and lot. It’s not about saving the planet first; it’s about not wasting your money on energy that leaks out through poorly insulated walls. If you’re looking at a new-build, you should also be thinking about how the property’s energy performance will affect its future value. A home that costs next to nothing to heat will always be easier to sell.
What the Future Homes Standard actually means for buyers
The most important thing to understand is that the Future Homes Standard doesn’t ban gas boilers by name. Instead, it sets carbon emission targets so strict that no fossil fuel heating system can meet them. That’s a subtle but crucial difference. A developer can’t just install a “hydrogen-ready” boiler and call it compliant — hybrid boilers and hydrogen-ready boilers will not comply with the standard. The only practical option for new homes is a heat pump, either air source or ground source.
What I’d do if I were buying today: I’d ask the developer for the predicted energy performance certificate rating and the specific U-values for the walls, roof, and windows. If they can’t give you those numbers, that’s a red flag. A home built to the Future Homes Standard should have external wall U-values around 0.15 W/m²K, compared to 0.26 W/m²K under the 2021 rules. That’s nearly twice as efficient.
Why running costs will separate good homes from bad ones
The financial difference between a well-insulated home and a poorly insulated one is not small. A typical three-bedroom home built to the Future Homes Standard is projected to cost between £400 and £700 per year to heat. Compare that to roughly £1,200 for an older home. That’s a saving of £500 to £800 every year, just on heating. Over a 25-year mortgage, that adds up to more than £15,000.
But there’s a complication. The Future Homes Standard Impact Assessment notes that bill savings compared to a 2021 new-build may be marginal, because heat pumps use electricity which costs roughly four times more per unit than gas. So the real savings come from the dramatically improved fabric — the insulation and airtightness — not from the heat pump itself. A heat pump in a leaky home will cost more to run than a gas boiler in the same house. The fabric has to come first.
What I’d do: I’d look for a home with mechanical ventilation with heat recovery (MVHR). In a very airtight house, you need controlled ventilation anyway, and MVHR recovers heat from the stale air being extracted. It’s a sign that the builder has thought about the whole system, not just ticked boxes.
Where buyers get tripped up
I’ve seen the same mistakes come up again and again. Here are the ones that cost the most money.
Assuming all new-builds are equally efficient
They’re not. A home built in 2024 under the 2021 Part L rules is significantly less efficient than one built in 2027 under the Future Homes Standard. The 2021 uplift required a 30% reduction in carbon emissions compared to 2013. The Future Homes Standard requires a 75% reduction. That’s not an incremental change — it’s a completely different performance level. If you’re buying a new-build that completed before March 2027, ask which standard it was built to. Don’t assume.
Ignoring the ventilation question
Highly insulated, airtight homes can be prone to overheating in summer. The Future Homes Standard works alongside Part O of the Building Regulations, which sets requirements for controlling solar gains and providing adequate ventilation during warm weather. But not all builders handle this well. If you’re looking at a home with large south-facing windows and no shading, ask how overheating is managed. A video doorbell won’t help with that, but a well-designed passive ventilation strategy will.
Overlooking the solar PV requirement
Under the new rules, developers must achieve PV coverage equivalent to 40% of the dwelling’s ground floor area where feasible. That’s a substantial amount of solar generation. But some homes built just before the deadline may have minimal or no solar panels. If you’re buying a home completed in 2025 or 2026, check whether solar PV was installed. If not, factor in the cost of retrofitting — and the lost savings from free electricity.
Not checking the compliance route
During the transition period, builders can use either the Home Energy Model (HEM) or SAP 10.3 to demonstrate compliance. Both achieve the same standard, but HEM provides significantly more accurate modelling, particularly for heat pumps, solar PV, and battery storage. If a developer used SAP 10.3, the predicted performance may be less reliable. Ask which route was used.
What I’d do: I’d ask for the full compliance report, not just the EPC. The EPC is a summary. The compliance report shows the actual U-values, airtightness test results, and heating system specifications. If the developer hesitates, that tells you something.
| Element | Part L 2021 (current) | FHS Notional (HEM) |
|---|---|---|
| External walls | 0.26 W/m²K | 0.15 W/m²K |
| Ground floor | 0.11 W/m²K | 0.13 W/m²K |
| Roof | 0.16 W/m²K | 0.16 W/m²K |
| Airtightness | 8 m³/(h·m²) @ 50 Pa | 3 m³/(h·m²) @ 50 Pa |
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How to choose a sustainable house and lot: a practical guide
Here’s the process I’d follow if I were buying today. It’s not complicated, but it does require asking the right questions before you exchange contracts.
Check the heating system first
If the home has a gas boiler, it was not built to the Future Homes Standard. That doesn’t mean it’s a bad home, but it means you’ll be paying gas standing charges and higher running costs. If the home has a heat pump, ask for the design temperature and the system’s coefficient of performance (CoP). A good air source heat pump should achieve a CoP of at least 3.0 in winter — meaning for every unit of electricity it uses, it delivers three units of heat. If the developer can’t tell you the CoP, ask for the heat loss calculation that was used to size the system. An oversized heat pump costs more to run and cycles on and off inefficiently.
Verify the fabric performance
Ask for the specific U-values for the external walls, roof, and ground floor. Compare them to the Future Homes Standard notional values in the table above. If the walls are above 0.18 W/m²K, the home is not performing at the level of a Future Homes Standard build. Also ask for the airtightness test result. A result above 5 m³/(h·m²) at 50 Pa suggests the builder didn’t prioritise airtightness. That means higher heat loss and more draughts.
Look at the ventilation strategy
In a home with airtightness below 5 m³/(h·m²), natural ventilation through trickle vents is not enough. The home should have either decentralised mechanical extract ventilation (dMEV) or mechanical ventilation with heat recovery (MVHR). MVHR is better because it recovers heat, but it costs more to install. If the home has dMEV, check that the extract fans are in the right places — kitchen, bathrooms, and utility rooms. If the home has no mechanical ventilation at all and the airtightness is below 5, walk away. You’ll have condensation problems.
Check the solar PV and battery storage
Under the Future Homes Standard, solar PV covering 40% of the ground floor area is the target. But not all homes will have battery storage. If the home has solar PV without battery storage, you’ll export surplus electricity to the grid at a low rate and buy it back at a higher rate later. Adding battery storage later is possible, but it’s easier and cheaper to install it at build time. Ask whether battery storage is included. If not, ask whether the inverter is battery-ready — some are, some aren’t.
Understand the “zero carbon ready” label
The government describes Future Homes Standard homes as “zero carbon ready.” That does not mean they produce zero carbon emissions today. It means they are designed so that they will become net zero carbon as the electricity grid decarbonises. The government’s target is clean power by 2035. Until then, your heat pump and appliances will still be powered by a grid that includes gas and coal generation. The home is future-proofed, not zero-carbon today.
What I’d do: I’d ask the developer for the predicted energy use in kilowatt-hours per square metre per year (kWh/m²/yr). A Future Homes Standard home should be below 50 kWh/m²/yr for heating and hot water. Anything above 80 kWh/m²/yr is closer to a 2013 standard home. That number tells you more than the EPC rating ever will.
Frequently asked questions
Can I still buy a home with a gas boiler after March 2027? ▾
Will a Future Homes Standard home really cost less to run? ▾
What happens if a developer doesn’t meet the Future Homes Standard? ▾
Do I need to install a heat pump if I buy an older home? ▾
What is the difference between HEM and SAP 10.3? ▾
Will solar panels be mandatory on all new homes? ▾
Sources and Further Reading
Smart UK strategies for first-time buyers — Practical advice on timing your purchase and negotiating in the current market.
Build equity with smart UK investment strategies — How to think about your home as a long-term financial asset, not just a place to live.
Future Homes Standard: technical requirements and compliance. Home Energy Model, 2026.
Government incentives for sustainable new-build homes. New Builds, 2026.
If this was useful, you might also want to read escaping the estate agent game: UK home buying hacks you never knew.
