Following the UK Government’s publication of the Future Homes and Buildings Standards on 24 March 2026, Eurocell is advising housebuilders and fabricators to prepare for significant changes to window and door calculations - changes that could accelerate the shift toward triple glazing across new build developments.

The updated framework, alongside Building Circular 01/2026 and revised Approved Documents L and F, requires all new homes to achieve 75 - 80% lower carbon emissions compared to 2013 standards - marking the most substantial uplift in energy efficiency requirements in over a decade.

The end of the ‘standard window’ model
A key change within the Future Homes Standard is the transition to the Home Energy Model (HEM), replacing the current assessment methodology.

One of the most impactful changes within this model is the removal of the generic “standard window” calculation. Manufacturers and housebuilders will no longer be able to rely on default models to demonstrate compliance.

Instead, every window must now be calculated individually, taking into account:
• The exact size of the window
• The specific glazing specification
• All frame components and ancillary profiles
• Elements such as cills, extenders, transoms, vents, dummy sashes and Georgian bars

Because most realworld window sizes are smaller than the historic standard used in calculations, achieving the notional 1.2 W/m²K U-value is set to become significantly more challenging.

When these smaller sizes are combined with additional elements that reduce thermal performance, many standard double-glazed units may no longer meet requirements making triple glazing a likely route to compliance for many new build projects.

"Now that the final details of the Future Homes Standard have been published, the real work begins for the new build sector. Because fabricators and housebuilders must now prove compliance down to the exact millimetre and component, we anticipate a rapid and necessary shift toward higher performance solutions like triple-glazing."

"At Eurocell, we are already working closely with our software partners and major housebuilders to navigate this transition. We are ensuring the sector has the bespoke calculators, technical guidance, and product solutions ready to go from today."

Gary Doxey, Commercial Manager at Eurocell

How Eurocell is supporting the transition
With the final requirements only recently confirmed, Eurocell has been rapidly preparing solutions to support customers through the transition:
• Specification to Installation: An end-to-end platform designed to handle the complexities of the Home Energy Model, ensuring accurate product-specific performance and carbon data from the design stage.
• Bespoke U-value calculators: Developed in partnership with leading software providers to deliver compliant, configuration-specific calculations.
• Housebuilder collaboration: Eurocell’s New Build Team is working closely with major developers to understand how these changes will influence future housing design.
• Ongoing technical guidance: Continued updates and detailed technical support to help interpret and apply the new standards.

Key dates to be aware of
• 24 March 2027: Future Homes Standard becomes mandatory for all new residential submissions
• 24 September 2027: Deadline for higher-risk buildings
• 24 March 2028: End of transitional arrangements (projects must have commenced)

For more information on how Eurocell can support your New Build specification under the Future Homes Standard, contact the team at newbuild@eurocell.co.uk.