The new driver in bifold doors?

By Sioned Webb, marketing director, Aluk.

Energy efficiency is not what initially drives a developer or a homeowner to purchase bifolds or sliding doors – certainly not in the way that it drives the purchase of windows;they are still essentially an aspirational lifestyle choice, meeting the very real demand for more open plan family living, and allowing homeowners to open up their properties to the garden.

Once buyers have made that lifestyle choice though, energy efficiency does now increasingly rank squarely alongside aesthetics and security in their list of buying criteria. Even a few years ago, that was not the case but, as the market matures, energy efficiency is becoming a key differentiator between products and indeed systems.

This explains in part perhaps the rise of the hybrid bifold alternatives, which up until now have promised users better thermal performance than aluminium. And, in turn, it also explains why Aluk has invested so much in ensuring that our brand new Luminia F82 bifold now beats those very same hybrids on energy efficiency.

The F82, which is officially launched this month, boasts a U-value of just 1.34W/m2K when double glazed. With symmetrical all-round rebates of just 97mm to provide larger glazing panels, it offers a combination of contemporary aesthetics, high security and energy efficiency which we think does away with the need for buyers to compromise on a hybrid at all.

For us, achieving slim sightlines for the F82 was absolutely critical to the design process, but we recognised that these could not be at the expense of thermal performance because there are downward pressures on energy efficiency at every point in the market.

For mainstream buyers, it’s all about saving on energy costs: in the premium retail market there is a growing desire to be ‘green’; and in the commercial sector we are starting to see the impact of the government’s Low Carbon Routemap for the Built Environment, which targets a 50% reduction in greenhouse gas emissions in the built environment by 2025 when compared to 1990 levels.

Moving forward, that Low Carbon Routemap will impact just as much on how products are manufactured as it does on how energy efficient they are, and we are already responding to it at Aluk by making new products like the F82 quicker and more efficient to fabricate than the current BSF70 bifold.

We have certainly not reached the limit of what we can achieve in improving the energy efficiency of our products either – there is still a lot of potential in the use of foam inserts in aluminium products for instance. But, we still face the very real issue of too few consumers really understanding what U-values mean and how they differ from Window Energy Ratings.

While there might be a basic appreciation of the fact that when it comes to U-values, the lower the better, I think much more needs to be done to communicate the fact that U-values and WERs are not interchangeable.

U-values show how much thermal energy is flowing through a construction element while WERs measure solar heat gain and air leakage rates alongside that. The reason why U-values are used for bifold and sliding doors is that, in many circumstances, solar heat gain is not desirable.

I appreciate that this is a fairly nuanced message, and perhaps the whole industry needs to join with Aluk’s Experts in Aluminium and do more to help installers who are selling to homeowners to communicate that. All our efforts to reduce the U-values of our products will surely count for nothing if the very consumers we are selling to don’t understand the benefits of that.