Recent Changes to Building Regulations in the UK Affecting Windows and Doors

In recent years, the UK’s building regulations have seen a series of important updates — particularly around energy performance, ventilation, overheating, security and compliance standards for windows and doors. These changes are designed to improve energy efficiency and comfort, reduce carbon emissions, support healthier indoor environments, and raise product quality and safety across the built environment. Whether you’re a homeowner planning an upgrade or a professional in the construction and glazing sector, it’s essential to understand how these regulatory shifts affect window and door systems.

Below we explain the key changes, what they mean in practice, how compliance works, and what may be on the horizon.

What Building Regulations Cover Windows and Doors

Before diving into the updates, it helps to know which parts of the Building Regulations most commonly affect windows and doors in the UK:

• Approved Document L – Conservation of Fuel and PowerFocuses on energy efficiency and thermal performance (including U-values) for windows, doors and the wider building fabric.

• Approved Document F – VentilationEnsures adequate ventilation to avoid condensation and poor indoor air quality.

• Approved Document Q – Security in DwellingsSets minimum security requirements for accessible windows and doors in dwellings.

• Other documents such as Approved Document B on fire safety may also be relevant in certain situations, but the most impactful changes over the past couple of years relate to energy, ventilation and security.

1. Stricter Energy Efficiency Standards (Part L)

One of the most significant recent changes affecting windows and doors relates to Approved Document L (Conservation of Fuel and Power) — originally updated with new performance standards coming into force in mid-2022 and continuing to evolve into 2025 and beyond. joinerysoft.com+1

What Changed

The 2021 edition of Approved Document L (effective from 15 June 2022) tightened U-value requirements for both new build homes and replacement windows and doors in existing dwellings:

Existing Dwellings (Replacement Work)

• Windows (including roof windows): maximum U-value of 1.4 W/m²K (or Window Energy Rating WER Band B minimum).

• Doors (glazed >60% internal face): maximum U-value 1.4 W/m²K (or Door Set Energy Rating DSER Band C).

• Other doors: maximum U-value 1.4 W/m²K (or DSER Band B).These standards replaced older, more lenient benchmarks, meaning many older units that previously complied will no longer satisfy the minimum requirements if replaced now. joinerysoft.com

New Build Dwellings

• U-value limits are generally stricter still — for example, a 1.2 W/m²K notional target for windows and glazed doors — to support new homes achieving lower overall energy demand. heronhurst.co.uk

Why It Matters

Lower U-values mean better insulation and reduced heat loss, translating to:

• Lower heating bills

• Reduced carbon emissions

• Improved comfort during UK cold seasons

These updated energy performance requirements are a stepping stone toward the Future Homes Standard expected in 2025-26, which will push performance even further. joinerysoft.com

2. Ventilation Requirements (Part F)

Closely tied to thermal performance are updated ventilation standards under Approved Document F (Ventilation). These changes recognise that modern windows and doors — designed with excellent airtightness — can inadvertently reduce natural airflow, increasing condensation risk and poor indoor air quality.

Key Requirements

From 15 June 2022 onward, most replacement windows and doors (especially in habitable rooms) must include background ventilation, such as:

• Trickle vents in window frames

• Other solutions demonstrating continuous ventilation without opening the sash

This requirement ensures a healthy indoor environment while still delivering improved energy performance. ggf.org.uk

Practical Impact

Installers and homeowners should be aware that:

• Simply replacing windows without providing ventilation may not comply with current regulations.

• Trickle vents must be specified and installed unless an alternative ventilation strategy is agreed with building control.

• This applies to both new builds and many retrofit projects. ggf.org.uk

3. Overheating and Solar Control (Approved Document O)

The UK has also introduced a new Approved Document O focused on overheating in dwellings, which is a growing concern as climate change leads to higher temperatures during summer months. c-a-b.org.uk

What It Does

Approved Document O guides designers and builders to mitigate unwanted solar gain, which can occur through extensive areas of glass in windows and doors. This can be addressed via:

• Solar control glazing or shading strategies

• Limiting glazed area where appropriate

• Orientation-based design choices

This document currently applies initially to new residential buildings and emphasises the need to balance airtight, energy-efficient envelopes with overheating avoidance measures. c-a-b.org.uk

4. Security Standards (Approved Document Q)

While not as frequently updated as Part L or F, Approved Document Q remains a fundamental requirement for windows and doors in new dwellings and certain extensions. It focuses on security — ensuring accessible windows and doors meet specific resistance criteria. GOV.UK

Security Requirements

Under Document Q:

• Easily accessible windows and doors must demonstrate compliance with British Standards PAS 24 (or equivalent).

• Certification via schemes like Secure by Design or UKAS-accredited test evidence is accepted for compliance. liniar.co.uk

What This Means

For manufacturers and installers, this means:

• Products must be tested to appropriate security standards.

• Replacements and new installations in new dwellings require evidence of compliance to satisfy building control.

5. Future Proposals and Possible Changes

Even with these recent updates, further developments are expected:

Future Homes Standard and U-Value Reporting

The Future Homes Standard proposes even more stringent energy performance metrics for new builds, including very low window U-values (potentially around 0.8 W/m²K) and greater emphasis on thermal bridging and whole-house energy modelling. KJM Group

Changes to how U-values are Declared

Proposals under consultation could mean manufacturers will need to calculate individualised U-values for each doorset and window configuration rather than applying a generic “model” figure. This may impact product certification and compliance processes. British Woodworking Federation

Potential Document Q Amendments

There are also discussions about updating security requirements, possibly broadening Document Q standards or how compliance is demonstrated. British Woodworking Federation

What Homeowners Should Do

If you’re planning window or door replacement or new installations in 2025 and beyond:

• Check U-value requirements under current Part L standards — and consider future-proofing (e.g., triple glazing for low U-values).

• Ensure ventilation compliance (e.g., include trickle vents or alternative systems).

• Understand security expectations if the work applies to new builds or extensions under Document Q.

• Work with certified suppliers and installers who are familiar with the latest Approved Documents.

• If your property is in a conservation area, additional planning requirements may also affect window/door work.

Conclusion

Recent UK building regulation changes reflect broader government goals: lower carbon emissions, healthier indoor environments, safer and more secure homes, and resilience to future climate challenges. For windows and doors, this has meant tighter energy performance standards, mandatory ventilation measures, overheating considerations and strengthened security expectations. Staying informed and compliant ensures not only legal conformity but better living comfort and long-term value for homeowners and the glazing industry alike.