When does a U-value not add value?

When purchasing new windows homeowners have a variety of factors to consider. Thermal efficiency usually features very high up on the list of priorities and is often explained within the industry using a U-value.

However, it’s important to keep in mind that a window’s U-value may not always be a true indication of value for money. Liniar Design and Development Director Chris Armes explains why.

“Most U-values consumers will see are completely obtainable, as many manufacturers quote products made using readily available, off-the-shelf components including the frames, glass, and spacer bars.

“However, sometimes it’s the gas that goes between the panes of glass or the glass itself which can be a bit of a red herring. For example, some companies promote windows with low U-values which have glazing units filled with Krypton, a gas that’s been on the market for a while now.

“Performance wise, these are absolutely fantastic. But as an analogy, it’s kind of like saying my car can go from zero to sixty in two seconds if I put rocket fuel in it! Although factually correct, it would be impractical since rocket fuel is expensive and not easy to get hold of.

“It’s the same thing with a window’s thermal performance. Liniar has long had Krypton simulations and we know the U-values our windows can achieve using the gas. But we don’t often quote that performance as we understand it can be cost prohibitive for many and not every manufacturer offers the gas as an option, making it more difficult to purchase windows which rely on it to achieve their low U-values.

“Over the years, due to excellent performance and wide availability Argon has emerged as the industry standard gas for filling glazing units. To my mind it therefore makes sense to quote the performance of Liniar products on something that’s going to be much more accessible with no hidden costs or a need for expensive components such as Krypton gas.

“What’s more, it’s not just the glass that contributes to a window or door’s energy performance, PVCu frames are crucial to providing whole-window insulation. And Liniar has established itself as a market leader in designing and manufacturing highly energy efficient profiles used to make window and door frames.”

In January 2023, the company launched its Passivhaus-capable, ultra energy efficient window and door systems Zero|90 and Zero 90R.

“With the launch of Zero|90 Liniar is offering a system capable of achieving a U-value of 0.66, one of the lowest on the market. But crucially, it does this with readily available Argon-filled triple glazing,” Chris explains.

He concludes, “As a company, we’re passionate about making the benefits of energy efficient home as accessible as possible, and in turn helping the UK on its journey towards Net Zero. One of the ways we aim to achieve this is through highly innovative design and avoiding reliance on cost-prohibitive components. That way, when we promote the U-values our products can achieve we can be confident they represent value-added performance to our customers.”

To find out more about Zero|90 visit https://www.liniar.co.uk/zero90/