What is the Future Homes Standard?

Updated 2 October 2026 — reviewed against the regs as they stand.

Quick answer: the Future Homes Standard is England’s next set of new-build energy regulations — published 24 March 2026 as Approved Document L 2026, and applying to schemes from 24 March 2027. New homes must emit at least 75% less carbon than 2013-standard homes, in practice meaning heat pumps or heat networks, tighter fabric limits and, for most houses, rooftop solar. As of August 2026, compliance at launch is assessed in SAP 10.3 (the Home Energy Model comes later).

What it is

The Future Homes and Buildings Standard (FHS) is the next generation of Building Regulations energy requirements for England, and the biggest change to new-build standards since Part L was last fundamentally rewritten. It requires new homes to produce at least 75% less carbon than a home built to 2013 standards — a step far beyond the 30-31% cut delivered by the Part L 2021 uplift.

The aim is homes that are zero-carbon-ready: low-carbon heating (in practice, heat pumps or heat networks), high fabric standards and on-site renewable generation, with no reliance on fossil fuels. A zero-carbon-ready home isn’t zero-carbon on day one — it’s designed so it becomes net-zero as the electricity grid decarbonises, needing no retrofit along the way.

The timeline

The final Approved Documents (new editions of Approved Document L Volumes 1 and 2, and Approved Document F Volume 1) were published on 24 March 2026, alongside the government’s response to the 2023 consultation and Building Circular 01/2026.

A 12-month transition period protects projects already in the pipeline — more on the detail below — after which the FHS applies in full.

The four big changes

1. Low-carbon heating — the effective end of the gas boiler

The FHS doesn’t “ban” gas boilers by name. Instead the 75% carbon reduction target is set at a level no fossil-fuel system can meet — so hybrid boilers and hydrogen-ready boilers won’t comply either. In practice that means air source or ground source heat pumps, or connection to a low-carbon heat network, in the vast majority of new homes.

This only affects new homes. Existing properties are unaffected: you can still install or replace a gas boiler in an existing house. The government estimates FHS homes will save households up to £830 a year versus a typical EPC-C property — though, honestly, savings against a Part L 2021 new build are more marginal, since heat pump electricity still costs roughly four times as much per unit as gas.

2. Fabric — the same U-values, tighter airtightness

The FHS keeps a whole-building performance approach, so you can trade off between elements. Two things catch people out. First, the U-values do not tighten: the limiting values are identical to Part L 2021 (walls 0.26, floors 0.18, roofs 0.16, windows and doors 1.6), and the SAP 10.3 notional dwelling has the same fabric U-values the 2021 notional already had — what tightens is its air permeability, from 5 to 4. Second, SAP 10.3 and the Home Energy Model share one notional dwelling — published as Appendix R of SAP 10.3 and, for HEM, as the dwelling notional buildings document — with only minor differences in implementation: HEM sizes the notional heat pump to the dwelling, where SAP fixes its seasonal COP (SCOP) at 2.5. The fabric is the same either way:

U-values in W/m²K; airtightness in m³/(h·m²) @ 50 Pa. The notional dwelling sets the target you have to beat; the limiting value is the backstop no element may be worse than. See our U-values guide for what these mean in practice, or test a wall, roof or floor build-up against these figures in the free U-value calculator.

One thing that doesn’t change: junction thermal bridging stays central to the fabric calculation. Calculated Ψ-values (see ΨMonkey) remain the best alternative to penal default values under both SAP 10.3 and HEM — and with a tighter air permeability and a heat-pump baseline, well-detailed junctions matter more, not less.

3. Mandatory solar PV — a genuine first

This is the headline everyone missed in the earlier drafts. A new functional requirement L3 makes on-site renewable generation a legal requirement of Building Regulations — the first time English regs have mandated renewable generation outright, rather than merely assuming it in the notional dwelling.

The rule (AD L1 para 5.73): an array whose annual output at least matches a fixed benchmark — panels of 0.22 kWp/m² over 40% of the dwelling’s ground-floor area, facing south-east to south-west, pitched at 45° and unshaded. In SAP 10.3 that comes to about 70.7 kWh a year per m² of ground floor, whichever way your roof faces; a south-facing roof gets there with slightly less than the benchmark’s kWp, an east–west roof needs around 13% more. Where the roof genuinely cannot take it, an array covering the reasonably practicable roof area is accepted instead. The solar PV calculator works out the target and what your own roof needs, and MHCLG’s FAQ on requirement L3 settles how north-facing slopes, garages and flats are treated.

That 40% sounds unchanged from SAP 10 — but there’s a catch. The conversion factor from roof area to installed power has changed from 1/6.5 (about 153 Wp/m²) to 1/4.5 (about 222 Wp/m²), reflecting more efficient modern panels. So while the headline number looks the same, the benchmark array is over 40% bigger than the one the 2021 notional dwelling assumed: about 0.09 kWp per m² of ground floor — 3.5 kWp for a 40 m² ground floor, 5.3 kWp for 60 m², 7 kWp for 80 m². Here is how many panels that is, by floor area and roof direction.

Exemptions: requirement L3 does not apply to buildings with a storey 18 metres or more above ground (the “relevant buildings” of regulation 7(4)), and where the whole usable roof cannot produce 720 kWh per year — for example because of heavy shading or awkward roof geometry — paragraph 5.77 treats it as an exceptional circumstance in which no PV may be required. For flats, tight roofs and the paperwork, see solar PV for flats, the reasonably practicable roof area and the evidence Building Control will want; our solar PV guide covers how it earns its keep in a compliance calculation.

4. Ventilation and airtightness — Part F tightens too

The notional dwelling’s tighter airtightness — 4.0, down from 5.0, with the 8.0 backstop unchanged — means continuous mechanical ventilation becomes effectively unavoidable in most FHS homes, whether decentralised mechanical extract (dMEV) or MVHR for the heat-recovery benefit: design below 5 and the updated Approved Document F no longer lists natural ventilation as a route (more below). It also sets out how systems are signed off:

• Installations are certified either by a registered competent person (self-certification) or by the building control body (AD F paragraph 4.2).
• Air flows from continuous extract and supply fans must be measured with a powered flow hood; a vane anemometer is still allowed for intermittent extract fans. The device needs a proprietary hood, ±5% accuracy and calibration within the last 12 months (paragraph 4.24).

Poorly commissioned ventilation has been a persistent problem in airtight new builds, and these changes are a direct response. They sit alongside completion-stage air tightness testing, which becomes more important than ever as targets drop.

The notional dwelling: one specification to beat

There is one notional dwelling. The 2023 consultation floated two — a stricter Option 1 and a less demanding Option 2 — and the government’s March 2026 response adopted Option 1’s fabric and services, with solar handled by requirement L3 instead. SAP 10.3 sets it out in Appendix R, Table R1:

You don’t have to build the notional: the targets are calculated from it, and you can trade one element off against another. Two of its lines shape most designs, though.

• Waste water heat recovery. Leave it out of a dwelling with more than one storey and you start behind the target, so the shortfall has to come from somewhere else — fabric, a more efficient heat pump or more PV. Our WWHRS guide covers the options.
• Airtightness decides the ventilation. At 4.0 the notional is “highly airtight” under Approved Document F 2026, which means a design air permeability below 5 (or an as-built result below 3). For highly airtight homes, natural ventilation — background ventilators with intermittent extract fans — is no longer a listed route (Table 1.6), so a design at 4.0 needs continuous mechanical extract, such as dMEV, or MVHR. Design at 5.0 or looser to keep natural ventilation and you carry an airtightness shortfall against the notional that has to be made up elsewhere; and if the finished home then tests below 3, AD F paragraph 1.46 calls for expert advice or continuous extract anyway. More in Part F 2026: what ‘highly airtight’ means.

How compliance is assessed: SAP 10.3 now, HEM later

Compliance is demonstrated the familiar way — showing your dwelling performs at least as well as a notional building of the same size and shape. Approved Document L 2026 retains the three Part L 2021 metrics: primary energy rate (DPER), carbon emissions rate (DER) and fabric energy efficiency (DFEE). No simplification — compliance stays multi-dimensional.

At launch, assessment is via SAP 10.3, an updated version of the familiar SAP methodology. The government’s new Home Energy Model (HEM) — a complete replacement for SAP that models performance at half-hourly intervals — was expected to follow around three months after publication, but was delayed again on 8 June 2026. As things stand, SAP 10.3 is the sole approved methodology, with HEM expected in the coming months, followed by a dual-running period before it eventually replaces SAP entirely.

HEM is a bigger shift than the version number suggests: it demands far more data than SAP (early testing suggests a house type takes around 1h40 in HEM versus roughly 20 minutes in SAP), with punitive defaults where data is missing, and it will be delivered through a single central calculation service rather than competing third-party engines. We’re tracking every software release closely.

What it costs

The government’s impact assessment puts the extra build cost at roughly £4,350 per dwelling (weighted average, 2025 prices) — or in the region of 3–8% per home — driven mainly by the heat pump, solar PV, extra insulation and mechanical ventilation. That’s offset by lower running costs and no gas standing charge, and the premium is expected to narrow as heat pump and PV supply chains scale up. Expect a surge in demand for both as the deadline approaches, so procurement planning matters.

Transitional arrangements

The 12-month transition runs from 24 March 2027 to 24 March 2028, and it’s stricter than previous uplifts:

• Projects with an application submitted before 24 March 2027 can build to Part L 2021 — if work commences before 24 March 2028.
• “Commenced” has the regulation 46A meaning (regulation 5(5) of SI 2026/335): for most buildings the foundations, any basement and the structure of the ground floor must be complete — digging foundations or laying drains is not enough. More in what “commenced” actually means.
• Arrangements operate on an individual-building basis, not site-wide, so different plots on the same site can fall under different regs.
• The 2013 transitional provisions (and the related 2021 provision) that still let some long-running sites build to 2010 standards are revoked — but a building already relying on them keeps that protection if work on it starts before 24 March 2028 (regulation 10). Any plot not started by then must meet the FHS.

What to do now

Projects gaining planning consent from here on will most likely be built under the FHS — so design for it now: heat pump heating, strong fabric, mechanical ventilation planned from the start, and solar PV sized to L3. Get the thermal bridging detailed properly while the drawings are live, and don’t fix a specification for 2027 starts before you’ve stress-tested it against the numbers.

We’re tracking the secondary legislation and software releases closely — talk to us before you lock in a spec, and we’ll tell you where the risks are.