How Windowmaker Built a U-value Calculator for Future Homes Standard Compliance with Eurocell.
Partner
Industry
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verified data points embedded in the platform
of Eurocell’s investment in developing and validating technical data
The regulatory background
On 24 March 2026, the UK government published the final Future Homes Standard regulations, updating Part L (Energy and greenhouse gas emissions) of the Building Regulations in England. The new rules apply to new-build work from 24 March 2027, with higher-risk buildings following from 24 September 2027 and transitional protection ending on 24 March 2028.
The headline U-value targets haven’t changed. The limiting value stays at 1.6 W/m²K for windows and doors, with the notional dwelling specification assuming 1.2 W/m²K. What has changed is how compliance is proven.
Under the previous methodology, a fabricator could calculate U-value once against a standard 1230 x 1480 mm reference window and apply that figure across the range. Under ADL1:2026, every window in a new dwelling must be calculated using the actual size and configuration. The standard reference window route survives only for existing dwellings. Ancillary components that affect thermal performance, including dummy sashes, frame extenders, Georgian bars, and coupling components, must now be included in the calculation.
For fabricators, this means the quoting process needs to do more work earlier. You can’t quote a U-value off a datasheet. You have to calculate it for the specific configuration the customer is ordering, and you need to see the rollup across the whole quote to know whether the dwelling will pass.
For more detail on the legislation, dates, and practical implications, see our full guide: The Future Homes Standard: What It Means for UK Window and Door.
What Windowmaker built
We developed a U-value calculator and calculation engine that sits inside our existing quoting workflow. As a fabricator or salesperson configures a window, the U-value and g-value update automatically against the actual product specification rather than a reference figure.
The system models every profile combination, handles multi-frame assemblies like bays automatically, and flags missing data before the quote goes out rather than producing a plausible-looking number. Outputs are structured for certification and the wider compliance chain, and fabricators and salespeople access everything through the same software they already use for pricing and ordering, meaning no change in their current workflow.
How Eurocell partnered with us
Eurocell was the first profile company to partner with Windowmaker on this. Their team validated Uf values, Ψ-values, and configuration data across their product range, and we embedded over 10,000 verified data points into the platform.
Because the integration happens at platform level, every Eurocell fabricator on Windowmaker gets the capability through their existing setup with nothing extra to install or manage.
“Eurocell’s clarity on what fabricators actually need from a compliance standpoint made this a genuinely collaborative build, not just a data hand-off.”
Head of Sales UK & Europe, Windowmaker
What this means for other profile companies
The calculation engine and quoting integration Windowmaker built for this collaboration work with any profile system. The architecture works the same way regardless of whose data is embedded. What changes is the data itself and the partnership to validate it.
The U-value calculator is one example of how we work with profile companies to turn a market shift into a product capability their fabricators can use immediately. If you’re facing a similar challenge, whether regulatory, technical, or commercial, let’s talk about what we can build together.
“By investing over two years in developing and validating our technical data and integrating it into Windowmaker’s platform, we have been able to help ensure fabricators can work within familiar systems while preparing for evolving requirements.
Talking about solutions is easy. Bringing them to life is more difficult. Massive thanks to Windowmaker for a truly collaborative approach.”
Head of Commercial Operations & Technical Sales, Eurocell
Working with profile companies
Profile companies sit at the start of every window our customers build. We work with them to make sure their systems reach fabricators accurately and quickly, whether that means responding to new regulation or getting a new product range to market. If something stands between your systems and the fabricators who use them, bring it to us. We’ll work with you to build the answer into the software they already use
About Windowmaker Software
Purpose-built for the fenestration industry since 1983, Windowmaker Software is the operational backbone for window and door businesses worldwide. What started as a specialist tool has grown into a complete platform that manufacturers and their supply partners rely on every day, in multiple languages and across markets.