In the first of two blogs about the history of high-end aluminium windows, this article will discuss the development of aluminium as a construction material and how it has changed over the decades, particularly concerning its thermal retention properties when used as a window frame. In the second blog the latest technologies, such as foamed EPDM gasket profiles, will be covered.
"When I was a boy I first heard about aluminium. It was a precious metal... [that] immediately captured my imagination. For a long time people have been extremely happy to claim heaviness as a virtue and merit of design. I was quite in opposition to the idea that architecture should be measured by the pound... On the contrary, I thought that if you could make it extremely light, it would be something of our own."
Richard J. Neutra
The Early Use of Aluminium in Buildings
Although aluminium was first used in the late nineteenth century as a construction material, its use in windows did not come about until much later. The major driver for this was the widespread construction of skyscrapers in the United States. Principally associated with the cities of New York and Chicago, such structures often adopted metallic window frames as a part of their design. Architects of the 1920s and 1930s in America tended to favour larger windows in their taller buildings to allow plenty of light in but they also needed to control solar heat. Therefore, an upturn in glazing technology development came about. Project engineers began replacing out-of-date single-glazing window units with the then brand-new double-glazed insulated glass units which often incorporated iron-rich glass that helped to control the indoor climate. Notably, aluminium frames were used on the Empire State Building with such units because they gave the right look and were sufficiently strong to hold the glazing. Architects like Frank Lloyd Wright used aluminium extensively for roofing and cladding applications as well as for window frames and doorways.
The 1970s and 1980s
It was only when the energy crisis came about in the 1970s that significant development into energy-efficient modernization of all kinds – including that of windows - took place. For example, the American government began funding research for better performing glass in window units for the first time. High thermal insulation aluminium windows were researched more thoroughly and it was soon found that a thermal break in the middle of the frame delivered greater efficiency. Since then, aluminium window makers have constantly researched the ways in which these thermal breaks can be improved on to provide ever greater performance. In some cases, makers simply added a powder coatable foam or a polyurethane foam to act as a thermal break between each side of the extruded aluminium frame, sometimes called the sandwich panel method. However, increasingly sophisticated methods have since been discovered.
More Recent Developments
As environmental considerations began to drive many building developments in the 1990s and 2000s, ever greater thermal efficiency was sought. Suitable for passive house use, high-end energy efficient aluminium windows began to incorporate ever more advanced thermal breaks. For example, some makers introduced the use of a polyamide 6.6 insulating strip in their products. This fibreglass-reinforced polyamide has anti-ageing properties as well as offering a good deal of thermal insulation, making it ideal for long-term installation. Other polymers were introduced, too, such as the ABS insulating strip which became renowned for its robustness and durability. A proven material, it has been used in things as diverse as children's toys to high-pressure cleaners. Some of the most recent research has been conducted in scientific studies to ascertain the exact performance of these materials when they are inserted into aluminium frames under precise configurations. It has been discovered, for example, that the exact position of how the thermal break touches the inside of the frame is crucial, and that the distance between the sections of extruded aluminium on either side of the window also plays a big part in the performance of a glazing unit. Read the second instalment of this blog for more information on the latest technological breakthroughs with energy-efficient aluminium windows.
Want to keep in touch?
Subscribe to our blog