The Future Homes Standard (FHS) will require all new homes in England to produce 75–80% less carbon emissions than homes built to the 2013 standards. For housing developers, this means heat pumps instead of gas boilers, mandatory solar PV, enhanced insulation, MVHR, and a new compliance methodology through the Home Energy Model (HEM). The additional build cost is estimated at 3–5% over current Part L compliance, but FHS homes will have significantly lower running costs — making them more attractive to buyers.
This page summarises the key impacts for developers. For detailed cost analysis, transitional strategy, and procurement guidance, see our Developer Compliance & Cost Guide.
Cost Impact Overview
The additional build cost is driven by several mandatory changes to how homes are built. The table below breaks down the main cost drivers and their estimated impact:
| Cost Driver | Part L 2021 (Current) | Future Homes Standard |
|---|---|---|
| Heating system | Gas boiler (~£1,500–2,500) | Air source heat pump (~£5,000–8,000) + hot water cylinder |
| Solar PV | Not required | Mandatory — ~£4,000–6,000 for typical 3-bed |
| Ventilation | MEV or trickle vents (~£300–500) | MVHR system (~£3,000–5,000 installed) |
| Windows | Double glazing (1.4–1.6 W/m²K) | Triple glazing (0.8–1.2 W/m²K) — ~£1,500–3,000 premium |
| Insulation | Standard Part L 2021 spec | Enhanced fabric — ~£1,000–2,000 additional |
| Airtightness | Standard construction detailing | Enhanced detailing + testing — ~£500–1,500 additional |
These figures are indicative and will vary significantly by house type, volume, and supply chain. Larger developers with established supply chains will typically achieve lower per-unit costs. The cost premium is also expected to reduce as the market scales up heat pump production and solar PV installation becomes routine.
Transitional Arrangements
The government has proposed a 12-month transitional period from when the FHS comes into force. Understanding these arrangements is critical for planning your pipeline:
- Plots registered before the FHS comes into force (expected late 2026) can begin construction under current Part L 2021 rules for up to 12 months
- Plots registered after the FHS comes into force must comply with FHS immediately
- After the transitional period ends (expected late 2027), all new homes must comply regardless of registration date
- Transitional arrangements operate on an individual building basis, not site-wide — different plots on the same site may fall under different regulations
- “Commence” is defined to include drainage and foundation work, not just superstructure
Key Dates for Developers
| Milestone | Expected Date | What It Means for Developers |
|---|---|---|
| FHS consultation response | Early 2026 | Confirms final regulations, fabric specs, and transitional arrangements |
| FHS comes into force | Late 2026 | Plot registration deadline for transitional eligibility |
| Transitional period | Late 2026 – late 2027 | 12-month window to commence Part L 2021 plots |
| Transitional period ends | Late 2027 | All new homes must comply with FHS — no exceptions |
These dates are subject to confirmation — the government response to the 2023 FHS consultation has not yet been published as of February 2026. See our Timeline & Status page for live updates.
Compliance Methodology
FHS compliance is demonstrated by showing that a proposed dwelling performs at least as well as a notional building of the same size and shape. During the transitional period, two routes are available:
- HEM via ECaaS: The primary route, using the Home Energy Model's half-hourly dynamic simulation through the centralised ECaaS platform
- SAP 10.3: An updated version of SAP available as an interim option during the dual methodology period
HEM requires substantially more detailed input data than SAP and takes longer to run (5–10 minutes per calculation versus near-instantaneous for SAP). However, it provides more accurate modelling of modern technologies, particularly heat pumps and solar PV. For a full comparison, see our Compliance Pathways page.
Frequently Asked Questions
How much more will FHS homes cost to build?
The government estimates an additional build cost of 3–5% over current Part L 2021 compliance. The main drivers are heat pump installation, mandatory solar PV, enhanced insulation (triple glazing), MVHR, and improved airtightness. However, FHS homes are expected to have energy bills 40–50% lower, which can support higher sale prices and improve buyer appeal.
What is the FHS plot registration deadline?
Plots registered before the FHS comes into force (expected late 2026) can commence under current Part L 2021 rules for up to 12 months. After the transitional period ends (expected late 2027), all new homes must meet FHS. Transitional arrangements operate on an individual building basis, not site-wide. See our Transitional Arrangements page for details.
Can developers still install gas boilers under the FHS?
No. The FHS carbon targets are set at a level that gas boilers cannot meet. New homes will need low-carbon heating — primarily heat pumps. Heat networks with low-carbon sources are also acceptable. Hybrid and hydrogen-ready boilers will not comply. During the transitional period, plots commenced under Part L 2021 can still use gas boilers.
What counts as 'commencing' construction for transitional purposes?
“Commence” is defined to include drainage and foundation work, not just superstructure construction. This is broader than some previous regulatory uplifts. To benefit from the transitional period, a plot must have commenced (including drainage and foundations) within the 12-month window after the FHS comes into force.
How much will FHS homes save on energy bills?
FHS homes are expected to have energy bills 40–50% lower than conventionally built properties. This comes from heat pump efficiency (2.5–4 units of heat per unit of electricity), mandatory solar PV, enhanced insulation, and MVHR (recovering 85–95% of exhaust air heat). As the grid decarbonises, these homes will also become progressively lower-carbon.
Related Pages
Developer Compliance & Cost Guide
Detailed cost analysis, transitional strategy, risk management, and procurement advice.
Transitional Arrangements
Plot registration deadlines, commencement definitions, and strategies for the transition period.
For Builders
What changes on site under the Future Homes Standard — heat pumps, MVHR, airtightness.
For Architects
How HEM changes design decisions for form factor, orientation, and glazing.