The Future Homes Standard comes into force on 24 March 2027, and it is a genuine step forward: every new home in England will be built with a heat pump instead of a gas boiler and solar panels on the roof. But it was announced in 2019, aimed at 2025, consulted on in 2023 and published last March, and in that time the country’s problem has changed. In 2019 the question was how to cut the carbon a single home emits. Now it is how to build the 1.5 million homes the government has promised while decarbonising the grid, keeping the lights on through winter and holding down bills. The Standard answers the first question well and barely addresses the rest, yet the houses it will govern are already being designed this autumn.
What Changes in March 2027
A new home in England will have to emit roughly 75% less regulated CO2 than one built to the 2013 standard, which in practice means a heat pump rather than a gas boiler, and it will have solar panels with a capacity equivalent to 40% of its ground-floor area. The solar obligation is also new in kind: it sits in its own requirement, “L3”, so unlike under previous versions of Part L it cannot be traded away by improving something else.
One Metric, Drafted for a Different Decade
Yet the Standard measures one thing: the annual CO2 emissions of a single dwelling, modelled as designed. Part L has used that metric for twenty years, and it made sense when the grid was dirtier, rooftop solar was rare, network capacity was not a constraint and the carbon in building materials was a smaller concern. None of that is true now, and three problems follow.
Free
Future Homes Standard Webinar
Thursday 26 November | 2pm
From Part L 2021 to Future Homes:
What Redesign Really Looks Like
How much will your housing designs need to change and at what cost?
We’ll compare three housing designs against the Future Homes Standard, showing the redesign required and the implications for design fees, build costs and residents’ running costs.
Omission One: The Metric Is Annual, the Grid Is Seasonal
First, the metric is annual and the grid is seasonal. Solar panels in this country produce around a sixth of their yearly output between November and February, and more than a third between June and August. Heating demand runs the other way, and the Standard adds to it by moving every new home’s heating from gas onto electricity. But the calculation counts a unit of electricity generated in July as worth the same as one used in January. To the grid they are not the same.
In summer, power is already plentiful and clean, and on sunny afternoons its price can fall to zero or below, so more rooftop solar saves little carbon and is increasingly wasted. In winter, when power is needed most, the panels contribute little, and wind or gas has to fill the gap. Batteries store energy for hours, not months. Counted over a year, the panels look like a large carbon saving; counted when the power is needed, the saving is much smaller, and the Standard cannot tell the difference.
Omission Two: The Network Sees the Peak, Not the Average
Second, the network has to carry the peak, not the average. Heat pumps move a home’s winter heating onto the electricity network, and that demand all arrives together. On the coldest, darkest evenings every heat pump on an estate runs hard at once, and the solar panels are generating nothing. This is a real load, not a modelled one, and a home-level annual emissions figure cannot see it.
As a result, connection capacity and substation sizing now sit on the critical path for larger sites, and they are settled by the distribution network operator, not by Building Control. Nationally, the UK looks increasingly likely to face an electricity crunch in the 2030s, having built no new gas power stations to meet its climate targets. It is hard to imagine a worse time to be adding to peak demand.
Omission Three: The Carbon in the Materials
Third, and largest, the Standard counts what a home emits in use and ignores what it took to build: the emissions from the concrete, brick, insulation and plant. The UK Green Building Council expects the built environment to emit around 1,700 million tonnes of greenhouse gases between 2024 and 2050. According to the Part Z campaign, over half of that is embodied carbon from new construction, none of it regulated, while building regulations, including this Standard and its sister Future Buildings Standard, cover less than a tenth.
Worse, every remedy the Standard prescribes adds material: more insulation, an array on every roof, a heat pump and cylinder in every plot. As emissions in use fall, the embodied share rises. Meanwhile London and a growing number of councils already assess whole-life carbon at planning, but Building Control does not, so the same scheme is judged against two definitions of carbon depending on which consent it is seeking.
Why This Matters
Why This Matters
None of this is an argument for waiting. The Standard will have to be met, and the decisions that determine how well are being taken now. The transitional arrangements are tighter than they look: to stay under the current Part L, a scheme needs its application in before 24 March 2027, and each plot, not the site as a whole, needs its ground-floor structure in place by 24 March 2028. Registering a site protects nothing that has not started.
Three Things to Do Now
First, design now for the plots completing after 2027. A heat pump at low flow temperatures needs larger radiators, a cylinder and plant space that a combi layout never did. A well-insulated home with generous glazing must pass the overheating test as well as the emissions one. And compliance moves to an unfamiliar half-hourly calculation model. Those choices affect roof layouts, densities and cost. The government’s impact assessment puts the average uplift at £4,350 per home; we expect the real figure to be two to three times that, and it will not get cheaper by waiting.
Second, make the mandated panels earn their keep. Heat pump controls that heat the hot water cylinder while the sun is out to use surplus generation should be standard. If PV panels have an east-west layout that spreads generation into the morning and evening. Thus keeping more of it in the home, rather than exporting it to a grid that needs it least at midday in June. A battery goes further. In summer it holds the afternoon’s output for the evening; in winter, when the panels produce little, it can charge overnight on cheaper off-peak power and carry the house through much of the evening peak.
Third, open the network conversation before layouts freeze, because connection costs and delays found late hit the programme. Also, tackle embodied carbon where the production line sets it: procurement. A volume builder’s specification is fixed centrally and bought in bulk, so the carbon in its bricks, blocks, concrete and insulation is decided by a handful of supply contracts, not on site. Ask suppliers to price lower-carbon versions of the same products at the same performance; a few changed contracts could reach tens of thousands of homes.
The fixes are not that exotic. The new compliance model calculates a home’s energy use half-hour by half-hour, which is a big step forward, but the Standard then adds it up into a yearly total and throws much of that detail away. Weighting each half-hour by how clean the grid is at that moment, factoring in PV panels exporting in June and a heat pump running flat-out on a January evening, would be the ‘real-world’ approach that we would take in a consultancy exercise. That is how to tell whether a home is genuinely low carbon. The new methodology misses that chance.
Add a limit on each home’s winter peak heating demand, the figure the network operator actually plans around, and an embodied carbon limit on each house type, and the Standard would be measuring the problems the country now has.
None of this needs new technology, only a decision to measure it. Until that decision is made, the Standard will make homes use less energy overall, but will also keep producing homes that pass on paper and leave the country’s harder problems exactly where they were.
Chris Hocknell, Director
Chris brings over 18 years’ experience of supporting the built environment and corporate world with their sustainability goals. Specialising in sustainability strategy development, Chris works closely with clients to assess and understand their carbon and environmental footprint.
Webinar
From Part L 2021 to Future Homes:
What Redesign Really Looks Like
Thursday 26 November | 2pm | 45mins + 15mins Q&A
Presented by: Yiota Paraskeva, Technical Director
What does moving from Part L 2021 to the Future Homes Standard mean for your housing designs and your project costs?
In this webinar for developers and design-and-build contractors, Eight Versa will present a comparative analysis of how current designs will perform against Part L 2021.
We’ll show what each achieves against the Future Homes Standard, where redesign is needed, and the implications for design fees, build costs and residents’ running costs.
Join us to explore:
What needs to change: the role of heat pumps, solar PV, MVHR and thermal bridging.
What redesign looks like: the changes required for each starting design.
What it means commercially: how design decisions affect costs, delivery and energy performance.
Understand where your current designs stand and which changes to prioritise.
