Future Homes Standard 2026: What It Means for Your Windows & Doors

The Future Homes Standard (FHS) is the most significant change to UK building regulations in a generation. First announced in 2019, it sets out how new homes must be built from 2025 onwards to produce at least 75% fewer carbon emissions than homes built under the previous regulations. For homeowners, self-builders and anyone planning an extension or renovation, understanding how the FHS affects windows and doors is essential.

What Is the Future Homes Standard?

The Future Homes Standard is an update to Part L (Conservation of Fuel and Power) and Part F (Ventilation) of the Building Regulations for England. It sets new minimum performance standards for the thermal envelope of buildings — walls, roofs, floors, windows and doors — and introduces stricter requirements for ventilation and airtightness.

The standard applies primarily to new-build homes, but its ripple effects are already being felt across the replacement window and door market. When Building Regulations are updated, the minimum performance requirements for replacement glazing also change. This means that anyone replacing windows or doors after the standard takes full effect will need to meet the new thresholds.

Key Changes for Windows and Doors

Stricter U-Value Requirements

The current minimum U-value for replacement windows is 1.4 W/m2K. Under the Future Homes Standard, this is expected to tighten to 1.2 W/m2K or lower. For new-build homes, window U-values of 0.8-1.0 W/m2K are being targeted, which effectively mandates triple glazing or very high-performance double glazing.

What this means in practice:

• Standard double glazing (U-value 1.2-1.4 W/m2K) will remain compliant for replacements in the short term
• Enhanced double glazing with warm-edge spacers and argon fill achieves 1.0-1.2 W/m2K and will meet the new standard comfortably
• Triple glazing (U-value 0.8-1.0 W/m2K) will become the default for new builds and the recommended specification for extensions

Both aluminium windows and uPVC windows from quality manufacturers already meet or exceed the anticipated requirements when specified with appropriate glazing.

Solar Gain and Overheating

The FHS introduces new requirements to prevent overheating — a growing problem in well-insulated, airtight modern homes. Large areas of south and west-facing glazing can cause uncomfortable internal temperatures during summer months, and the standard now requires designers to demonstrate that overheating risk has been mitigated.

This affects homeowners considering:

• Large sliding doors or bifold doors on south-facing elevations
• Floor-to-ceiling glazing in extensions
• Roof lanterns and skylights — particularly in kitchens and living spaces

Mitigation measures include solar-control glass (which reduces heat gain while maintaining light transmission), external shading, adequate opening windows for cross-ventilation, and careful orientation of large glazed areas.

Ventilation Requirements

Part F ventilation requirements are being strengthened alongside the thermal standards. Better-insulated, more airtight homes need controlled ventilation to prevent condensation, mould and poor indoor air quality. For windows, this means:

• Trickle vents will remain a requirement on most replacement windows
• Mechanical Ventilation with Heat Recovery (MVHR) systems will become standard in new builds
• Opening windows must be positioned to enable effective cross-ventilation

All windows we install include trickle vents as standard, meeting both current and anticipated ventilation requirements.

Airtightness Standards

The FHS targets an air permeability of 5 m3/h/m2 or better, compared to the current standard of 10 m3/h/m2. This has direct implications for window and door installation quality:

• Frame-to-wall junctions must be properly sealed
• Threshold detailing on doors becomes critical
• Factory-finished systems with integrated seals outperform site-applied sealants

Premium aluminium systems from Cortizo and Schuco are designed to achieve the highest levels of airtightness, with multi-chamber profiles and factory-fitted gaskets that far exceed the minimum requirements.

How Does This Affect Homeowners Replacing Windows Today?

If you are replacing windows or doors in an existing home in 2026, you need to comply with the current Building Regulations, not the full Future Homes Standard (which applies to new builds). However, there are strong reasons to exceed the minimum:

• Future-proofing: Installing windows that meet or exceed FHS requirements means they will still be compliant if regulations tighten further
• Energy savings: Higher-performance glazing saves money on energy bills year after year
• Property value: Buyers increasingly value energy-efficient homes, and an EPC rating boost adds measurable market value
• Comfort: Better insulation and airtightness mean fewer draughts, less condensation and more consistent room temperatures

What Specification Should You Choose?

Based on current and anticipated requirements, here is our recommended specification for different project types:

Replacement Windows in Existing Homes - **Minimum:** Double glazing with U-value 1.2 W/m2K, low-E coating, argon fill, warm-edge spacer - **Recommended:** Enhanced double glazing with U-value 1.0-1.2 W/m2K - **Premium:** Triple glazing with U-value 0.8 W/m2K (ideal for north-facing elevations and exposed positions)

Extensions and Conservatories - **Minimum:** Double glazing with U-value 1.2 W/m2K - **Recommended:** Triple glazing where practical, solar-control glass on south-facing elements - **Critical:** Adequate opening windows for ventilation, consider overheating analysis

New Builds and Self-Builds - **Standard:** Triple glazing throughout with U-values below 1.0 W/m2K - **Windows:** Aluminium or uPVC with advanced thermal breaks - **Doors:** Composite or aluminium entrance doors with U-values below 1.4 W/m2K - **Roof glazing:** Solar-control glass as standard on [roof lanterns](/korniche-roof-lanterns) and skylights

The Cost Implications

Meeting FHS requirements does add to the cost of glazing, but the premium is modest:

• Enhanced double glazing (U-value 1.0-1.2) adds approximately 5-10% to the cost of standard double glazing
• Triple glazing adds approximately 15-25% to the cost of standard double glazing
• Solar-control glass adds approximately 10-15% per pane

For a full house of windows, the additional cost of specifying enhanced double glazing over standard is typically £500-£1,500. Triple glazing adds £1,500-£3,500 for a typical three-bedroom house. These costs are offset by ongoing energy savings and the increase in property value associated with a higher EPC rating.

Frequently Asked Questions

Does the Future Homes Standard apply to replacement windows?

The FHS primarily applies to new-build homes. However, replacement windows must comply with current Building Regulations Part L, which already requires a maximum U-value of 1.4 W/m2K. This threshold is expected to tighten in the coming years, and installing higher-performance glazing now means you will not need to upgrade again.

Will I need triple glazing on my extension?

Not necessarily under current regulations, but the overheating and energy performance requirements of the FHS make triple glazing the recommended choice for most extensions — particularly those with large areas of south or west-facing glass. Your architect or building control officer can advise on what is required for your specific project.

Do trickle vents become mandatory under the FHS?

Trickle vents are already required on most replacement windows under current Building Regulations. The FHS reinforces this requirement and places greater emphasis on whole-house ventilation strategies. All windows we install include trickle vents as standard.

What U-value should I specify for windows in 2026?

For replacement windows, we recommend a minimum of 1.2 W/m2K (which exceeds the current minimum of 1.4) and ideally 1.0 W/m2K where budget allows. For new builds and self-builds, aim for 0.8-1.0 W/m2K with triple glazing. These specifications provide genuine future-proofing against further regulation changes.

How does the FHS affect doors?

The FHS sets a maximum U-value for external doors of 1.4 W/m2K for new builds. Solid composite doors already achieve this comfortably. Doors with large glass areas — such as bifold and sliding doors — need to be specified carefully to meet the requirement, particularly with extensive glazing. Premium aluminium systems with triple glazing meet the standard without difficulty.

Will my home's EPC rating change under the new standards?

If you upgrade your windows and doors to FHS-compliant specifications, your EPC rating will improve. The extent depends on your starting point, but moving from old double glazing to enhanced or triple-glazed units typically improves an EPC rating by one band (e.g., D to C). This can add measurable value to your property and may be required for rental properties.