Aluminium or PVC?

There’s a common misconception though that uPVC ranks higher than aluminium when it comes to thermal performance. While that might have been true in the 1970s and 80s when naturally conductive aluminium frames were manufactured without a thermal break, it is certainly not the case today.

It was the inherent insulating properties of unplasticized Poly Vinyl Chloride (uPVC) which helped to make uPVC windows so popular in the first place, coupled with the fact that the frames also featured multi-chamber profiles to prevent heat loss. Added to that of course was the fact that those early uPVC windows were very budget friendly and promised life spans of up to 25 years.

For decades then, uPVC was probably the first choice for homeowners who wanted to save energy. But aluminium started to catch up with uPVC in the mid 2000s, and now there is very little difference in terms of performance. In fact, there are lots of arguments that aluminium windows, which are 100% recyclable and offer lifespans of more like 40 years, are overall a more environmentally friendly and sustainable choice. This is especially true for heritage-style aluminium window and door systems, which offer classic aesthetics alongside modern performance.

In reality, since the late 1980s, almost all aluminium windows have been designed with a highly efficient thermal break inside the frames made from a non-conductive polyamide material. This provides an effective barrier between inside and out and doesn’t just keep the heat in and the cold out but also prevents condensation from forming.

Of course, glazing options also have a major impact on the thermal efficiency of windows and doors and your choice of argon or krypton filled, double or triple glazed glass units can be just as important as your choice of frame material. This applies just as much to contemporary frames as it does to heritage aluminium doors and windows, which are often chosen for period homes or properties in conservation areas where maintaining the original look is essential. For homeowners wanting a sleek, modern alternative, aluminium systems like the S67 slimline door or the robust S140 sliding door also deliver exceptional thermal performance and design flexibility.

Since the early 2000s, AluK has been a powerhouse when it comes to aluminium window design, and, in 2007, we developed and marketed the UK’s very first ‘A’ rated window in aluminium with a double glazed sealed unit which matched the best available in uPVC.

We have continued to innovate since then – and our aluminium windows are also now fitted with additional high density foam insulation in the thermal break. This ensures that we don’t just meet, but also exceed the minimum thermal performance standards laid down in the Building Regs – you can read all about that here.

We never lose sight of the fact that energy efficiency is just one of the top priorities for buyers though. Aluminium easily matches uPVC when in terms of thermal performance, but, when it comes to the other priorities including aesthetics and sustainability, we easily outperform not just uPVC but timber and steel as well. This is particularly relevant for those choosing heritage systems, or looking to upgrade to modern aluminium door options like the Optio 58 BD HI or the 77ID, where aluminium offers the perfect blend of design, durability, and energy efficiency.