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Stellar ready for the changes to Part L

3rd February 2022

The new Part L of Building Regulations, which comes into force on 15 June 2022, is the biggest shake-up of thermal performance regulations for a number of years. As such, the regulations will be especially complicated for many aluminium systems to meet. But one system is good to go already – Stellar, the multi-ward-winning aluminium system from Epwin Window Systems.

Phil Parry, Business Development Director at Epwin Window Systems, says: “Stellar’s unique design doesn’t use dummy sashes or rebate adaptors so it’s more thermally efficient by design. Plus, its thermal breaks can be upgraded to meet the demands of thermal regulations that will only get stricter over time. It means we’re already ahead of the market and many systems will have to be redesigned and reconsidered to meet the new requirements.”

The new regulations pose a problem for many aluminium systems because of the way the U value now must be calculated. Instead of being calculated on a 1230w x 1480h single opening casement (known as the CEN standard window), U values must be calculated on the GGF 2.2 window configuration, as used in WERs. This is a window with an opening light next to a fixed light with a central mullion. It’s harder to achieve the required U value on this configuration because there is more frame than in a CEN standard window. It’s especially problematic for aluminium windows that use a dummy sash or rebate adaptor to create an internally beaded fixed light next to an opener because they use even more frame.

Stellar is unique because it uses a patented reverse butt joint. It means there’s no need for dummy sashes, reverse profiles or adaptors. It helps it to meet the requirements of the new Part L legislation with the added benefit of being ready for the proposed amendments to Approved Document Q too.

To illustrate the difference the patented construction makes, Epwin Window Systems’ certified BFRC simulators simulated two GGF 2.2 windows. The first was a Stellar window constructed with a dummy sash. The second was Stellar window constructed using the patented reverse butt joint.

The reverse butt jointed window achieved a calculated improvement of 0.1W/(m2K) over the dummy sash variant.

Phil concludes: “Stellar was always designed to be competitive yet future proof. It’ll be ready for the changes now and it’ll be ready in the future too. Its stunning aesthetics mean it attracts consumer attention like no other aluminium system. And with the introduction of the new Part L, there’s yet another reason for it to be the aluminium system of choice in fabricators’ and installers’ portfolios.”

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