Future Homes Standard: Why early fenestration decisions will be critical

The Future Homes Standard ADL Volume 1: Energy and greenhouse gas emissions will bring a fundamental change to how residential window and door performance is assessed - and the time for the construction industry to prepare is now.

For developers, architects, specifiers and contractors, the biggest shift will be the move towards project-specific calculations. Rather than relying on standard assumptions, fenestration performance will need to reflect the actual size, configuration and specification of every installation.

A new approach to compliance

Under previous versions of Approved Document L, residential window and door U-values could be assessed using actual product dimensions, a standard reference configuration or hot-box testing.

The removal of the standard reference configuration route means this approach will change. Future assessments will require greater accuracy, with product performance linked directly to the specific characteristics of each project.

This means fenestration decisions made early in the design process will play an increasingly important role in achieving energy targets and demonstrating compliance.

Why action is needed now

Residential projects due for completion from 2027 onwards are already moving through design and specification stages. This means decisions around building fabric performance are being made now - often before the new requirements come into force.

Changing specifications later in the process could create unnecessary cost, delays and compliance challenges.

John McComb, Technical Director at Reynaers Aluminium UK, said: “This transition marks a significant change in both the process and methodology used to demonstrate compliance in the new build residential setting, requiring considerably greater levels of design accuracy, coordination and performance forecasting from the earliest stages of a project.”

Supporting a more data-driven approach

The move towards detailed, project-specific calculations is already familiar within commercial fenestration, where performance modelling and verified data are established parts of the specification process.

As residential projects adopt a similar approach, collaboration between manufacturers, designers and contractors will become increasingly important.

With independently verified thermal simulation capabilities and digital tools such as ReynaPro, Reynaers is supporting stakeholders with accurate project data, improved traceability and greater confidence throughout the specification process.

The Future Homes Standard is an important step towards improving the energy performance of UK housing. However, meeting its ambitions will require the industry to embrace a new way of working — where early collaboration, accurate data and informed specification decisions become central to delivering compliant, energy-efficient homes.

Find out how Reynaers can support your Future Homes Standard requirements:
https://www.reynaers.co.uk/