High-end Aluminium Windows - Improvement of the Thermic Values is Becoming Progressively More Difficult

By Bogdan Grebenyuk, Product Manager at Thermevo
on Dec 27, 2017
Polyamide insulating strips are among the most advanced technologies used in today's high-end aluminium frames, but what of the future?
Before looking into the future of aluminium as one of the new materials for window and door frames, it is worth reflecting that it was first extracted only in 1854. The first widely accepted use of aluminium in a building was the dome of San Gioacchino's Church in Rome, constructed as late as 1898. New York's Empire State Building was the first large structure to utilise anodised aluminium components in the 1930s. However, the widespread industrial production of the metal for civil applications, such as high-end window frames and walling systems really only took off from the 1950s onwards. Since then, much work has been done on improving the hollow chamber profiles of aluminium window frames to augment their thermal performance. From a thermal break with an ABS insulating strip to more efficient thermal separation caused by low lambda polyamide insulation profile engineering, a U(f) value of less than 1.0 – something of a must for every system architect – is now frequently possible. But, with so many advances from the top window manufacturers, what is left to be improved on?

Developing Polyamide Insulation Bars with Reduced Lambda Value

Due to the success in recent years of producing a low lambda polyamide insulation profile with an array of bespoke aluminium window frames, specifiers and building designers of all kinds may be forgiven for thinking that high level research does not continue in the field of windows. However, studies do take place in laboratory-like conditions in order to meet some of the most exhaustive demands that architects come up with in their projects.

"In the last couple of years, there's been a real evolution in window framing, curtain wall framing, and store front framing...[using an] aluminium frame, but there are different technologies embedded into it that separate it into two halves and block heat loss."

Tom Culp of Birch Point Consulting. Some the latest research in diminishing the lambda value of aluminium framed windows to the lowest points possible has been in the precise distances between the frame's aluminium components

on either side of the glass. Studies have shown this is crucial to thermal efficiency so long as any internal polyamide insulating strip touches the frames in as minimal a way as possible. Of course, this means that precise engineering is required to manufacture frames with the lowest possible U(f) ratings.

The Driving Factor of the PassivHaus or Passive Home

In Europe, the passive home is commonly ascribed to a dwelling that can achieve a maximum winter heating load of no more than 10 Watts per square metre. For obvious reasons a key part of obtaining this sort of energy efficiency comes down to specifying windows with the right sort of thermic values. The low energy consumption building is still high on the agendum of many building designers, so the resources necessary to improve windows with new materials continue to be deployed. Frequent industry symposia are held into passive homes, specifically focussing on the challenges of windows. Current trends indicate that the industry is asking itself how it will be able to produce thermally superb windows which still fit in with the requirements of architectural heritage, when retro-fitted, and the more widespread use of triple glazing units in newly built passive buildings.

Patents Pending

With so much activity in the field of aluminium windows, further improvements to thermic values are expected to be seen in the near future, despite the undoubted difficulty in bettering already good results. Innovations, such as a newly patented technology, in which thermal break profiles with foam are integrated into aluminium frames, have already begun to be seen in some buildings. Added to new technologies like novel gaskets with superb levels of air tightness and reflection film (e-low film) which covers the glazing panels themselves, it would be foolish to think that research into the thermally efficiency of aluminium window frames and glazing shows any signs of slowing.

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