Future Homes Standard 2025 What It Means for Windows
A new window that meets the Future Homes Standard will cost roughly £150 to £350 more than a standard triple-glazed unit installed under 2022 Building Regulations. This higher upfront cost is offset by a 15 to 20 percent reduction in annual heating demand compared with a 2022-standard window (DESNZ, 2023 consultation response).
A standard triple-glazed window installed under 2022 regulations costs between £400 and £600 per window. A Future Homes Standard (FHS) compliant window costs between £550 and £950 per window, based on MCS installer cost surveys. The higher cost is partly offset by lower heating bills and the ability to install a smaller, cheaper heat pump. The payback period depends on the number of windows in the home and the quality of the existing building fabric.
The Future Homes Standard applies to new homes from 2025, with transitional arrangements meaning most homes will be built to the standard from 2026. However, the window specification will also influence replacement windows in existing homes through updates to Part L of the Building Regulations (DESNZ, 2023 consultation response).
Quick numbers Key performance metrics for FHS-compliant windows
| Metric | 2022 Part L minimum | FHS 2025 target |
|---|---|---|
| Centre-pane U-value (W/m²K) | 1.4 | 0.8–1.0 |
| Whole-window U-value (W/m²K) | 1.8 | 1.2–1.4 |
| G-value (solar heat gain coefficient) | 0.4–0.6 | 0.5–0.6 (orientation-dependent) |
| Air leakage rate (m³/h/m² @ 50 Pa) | 2.0 | 1.0 |
| Typical frame material | uPVC, timber, aluminium | uPVC with thermal break, timber, aluminium with triple glazing |
Source: DESNZ, Future Homes Standard: technical specification and BRE, Window energy ratings.
What is the Future Homes Standard and how does it affect windows?
The Future Homes Standard is a set of regulations for new homes in England, effective from 2025 with transitional arrangements into 2026. It sets a fabric energy efficiency target that is 75 to 80 percent lower carbon than 2013 Building Regulations levels (DESNZ, 2023 consultation response).
Windows are a primary lever for meeting this target. The standard mandates whole-window U-values of 1.2 to 1.4 W/m²K. This forces the use of triple glazing and thermally broken frames. The standard also requires airtightness improvements, so window installation must achieve a maximum air leakage of 1.0 m³/h/m² at 50 Pascals (DESNZ, 2023 consultation response).
For comparison, the 2021 Approved Document L allowed a whole-window U-value of up to 1.8 W/m²K (Approved Document L 2021).
What U-value must a window achieve to meet the Future Homes Standard?
The whole-window U-value must be 1.4 W/m²K or lower for most new homes. An aspirational target of 1.2 W/m²K is recommended for optimal heat pump sizing (DESNZ, Future Homes Standard: technical specification).
The centre-pane U-value must be 1.0 W/m²K or lower. This typically requires triple glazing with two low-emissivity (low-E) coatings and argon or krypton gas fill. The standard does not mandate a specific glass type. Triple glazing is the only cost-effective route to these figures. Double glazing with low-E coatings can achieve 1.4 W/m²K but cannot reliably achieve 1.2 W/m²K (Approved Document L 2021).
How do I verify that a window is Future Homes Standard compliant?
Check the window’s British Fenestration Rating Council (BFRC) energy rating label. FHS-compliant windows must achieve at least A-rated (whole-window U-value of 1.2 W/m²K or lower) or B-rated (U-value of 1.4 W/m²K or lower) with a clear specification sheet (BFRC, Window energy rating scheme).
Installers must be registered with a competent persons scheme. For windows, this is FENSA or CERTASS for new-build work, or MCS if the window is part of a heat pump system. The window must have third-party certification confirming the whole-window U-value and air leakage rate. Acceptable certification bodies include BFRC, KIWA, or a UKAS-accredited test laboratory (FENSA, Competent Persons Scheme requirements).
How does the Future Homes Standard affect replacement windows in existing homes?
The Future Homes Standard does not directly apply to replacement windows in existing homes. However, Part L of the Building Regulations (2021) already requires replacement windows to achieve a whole-window U-value of 1.4 W/m²K or lower (Approved Document L 2021).
From 2025, Part L is likely to tighten to match the FHS targets. This means replacement windows will need to achieve 1.2 to 1.4 W/m²K, effectively requiring triple glazing for most homes (DESNZ, Future Homes Standard: impact assessment).
The practical effect is that any homeowner replacing windows after 2025 should specify triple glazing now to avoid having to redo the work later when regulations tighten. guide to Part L building regulations for replacement windows
What are the trade-offs between double glazing and triple glazing under the Future Homes Standard?
Double glazing has a lower upfront cost, typically £400 to £600 per window installed. However, it cannot reliably meet the FHS U-values. The home’s heat pump must be larger to compensate for the higher heat loss, increasing the overall system cost (Energy Saving Trust, Triple glazing vs double glazing).
Triple glazing has a higher upfront cost, typically £550 to £950 per window installed. It meets the FHS U-values reliably. It reduces the required heat pump size by 10 to 15 percent, saving £500 to £1,000 on the heat pump installation (BRE, Window energy performance: a comparison).
There are trade-offs. Triple glazing adds weight, up to 40 percent heavier per pane. This may require stronger frames and more solid opening mechanisms. Triple glazing also has lower solar heat gain in winter, which can increase heating demand by 2 to 5 percent in south-facing rooms (Energy Saving Trust, Triple glazing vs double glazing).
How much will FHS-compliant windows cost and what grants are available?
The installed cost for an FHS-compliant window is £550 to £950 for a standard 1.2 metre by 1.2 metre opening. This compares with £400 to £600 for a 2022-standard triple-glazed window (MCS installer cost surveys).
The Boiler Upgrade Scheme (BUS) provides £7,500 towards the cost of a heat pump (GOV.UK, Boiler Upgrade Scheme: guidance). The scheme does not specifically cover windows. However, installing better windows allows you to fit a smaller heat pump, reducing the overall system cost.
The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. guide to Boiler Upgrade Scheme eligibility for heat pumps
Frequently Asked Questions
The Future Homes Standard sets stricter fabric energy efficiency targets for new homes from 2025. For windows, it requires a whole-window U-value of 1.2-1.4 W/m²K and air leakage below 1.0 m³/h/m² at 50 Pa, according to DESNZ.
FHS-compliant windows cost £550 to £950 per window, which is £150 to £350 more than a standard triple-glazed unit meeting 2022 regulations. MCS installer cost surveys provide these figures.
Yes, FHS windows reduce annual heating demand by 15 to 20 percent compared with 2022-standard windows. This is based on DESNZ's 2023 consultation response.
The standard applies to new homes from 2025, with transitional arrangements meaning most homes will be built to it from 2026. Replacement windows in existing homes are affected through updates to Part L of the Building Regulations.
FHS windows need a centre-pane U-value of 0.8-1.0 W/m²K and a whole-window U-value of 1.2-1.4 W/m²K. This is a significant improvement from the 2022 Part L minimum of 1.4 and 1.8, as set by DESNZ.
