Energy efficiency made simple

Nigel Headford
Nigel Headford

Energy efficiency was at the top of the list when Deceuninck Aluminium designed the new Decalu88 flush casement window. Director Nigel Headford explains why.

Right now, many aluminium systems struggle to meet the new Part L requirements with a double glazed unit. And many of these systems are relatively new to market.

To recap, windows and doors (with a >60% glazed area) going into a refurbishment project need to achieve a U-value of 1.4W/m2K. This drops to 1.2W/m2K for newbuild, as well as extensions on existing properties.

The Future Homes Standard – expected to come into force in 2025 – will require even better thermal performance, with U-values as low as 0.8W/m2K suggested. While this will be for newbuild, it is likely that U-values for refurbishment projects will also be tightened further.

At Deceuninck Aluminium, we clearly saw the way the market was heading, and it made no sense to not design in energy efficiency as a key feature. As it turns out, we are now speaking to developers who fully intend to specify ultra-energy efficient windows and doors as standard, long before it becomes a legal requirement.

And, we know from our experience with the Decalu88 bi-folding door, that homeowners are demanding increasingly thermally efficient products regardless of when the government plans to tighten the Building Regulations – much of our new business in the last four years has come via this route.

So, during the Decalu88 flush casement window design stage, we included favourite features such as the pre-inserted gaskets and knock-in glazing bead, and made it flush on the inside and flush on the outside.

But we also asked: how do we design an open-out casement window that performs to – and exceeds – the new regulations? And can we do a 400mm drop with an 88mm deep window?

This meant working with hardware manufacturers and other suppliers at a very, very early stage, to ensure that our window worked.

And we also wanted to design just one window – one that can go into newbuild and perform at one U-value, and go into refurbishment projects and perform at another U-value.

Traditionally, you would have a basic window design and add elements that would allow it to perform at a higher level. But we just decided to make a top performing window, and if you needed to enhance it further, you could just change your glass specification.

That way, you’ve got a simple cost base, and you don’t have to worry about getting additional parts, which fits our philosophy of reducing stock holding and making life simpler for both fabricators and installers.

The result is a headline U-value of 0.8W/m2K, achievable in a triple-glazed configuration. But – more importantly in my opinion – it can achieve a U-value of 1.2W/m2K with a double-glazed unit with a centre pane U-value of 1.0W/m2K.

That means it will meet Part L requirements for newbuild, double glazed. And with a ‘standard unit’ with a centre pane U-value of 1.2W/m2K it’s 1.4W/m2K, which meets Part L requirement for home improvement.

Because the energy efficiency is designed in from a very early stage, it means that achieving lower U-values doesn’t come as an afterthought. This is what we are seeing with other systems on the market, and it leaves us scratching our heads.

If you are a fabricator, you don’t want to second-guess the requirements, and buy-in extra components just to comply. This ties up extra money in stock holding, and it increases the chances of error.

And if you are installer, you could have a mixture of requirements on a single job – one U-value for the replaced windows, and another for the doors on the extension. Isn’t it reassuring that it is only the glass spec that changes, and all other components remain exactly the same?

We set out to future-proof the Decalu88 flush casement window, which is now paying dividends for fabricators, installers, and homeowners.

Deceuninck Ltd
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