“Doors, windows and vents are only a small part of the facade, but they are the only part that users interact with physically. And they look so clumsy and boring,” says Stephen Tanno, director of the facade engineering group at Buro Happold. He is so disgusted with the European curtain-walling industry’s output that he has decided to do something about it – starting with the humble patio door.
Not so humble if you consider the size of the market, which the European Aluminium Association says is worth £228m a year. To come up with “a better product with better performance”, Tanno set up a collaborative research and development project with Swedish curtain-walling manufacturer Sapa Group, the fourth-largest aluminium company in the world and owner of British curtain-wall manufacturer Glostal and extrusion company Indalex.
Tanno regards the poor design of patio doors, with their boxy frames in yellowing PVCu, as a microcosm of the general malaise afflicting curtain-walling systems. Tanno, who claims to have been a founding father of the facade engineering discipline in Sydney, Australia, in 1988, says: “The curtain-walling industry is caught up in an out-of-date technology of panels and sticks. We call it incremental technology, because every year the manufacturers refine their designs ever so slightly. But there are still the same window profiles with the same width as the Crittall steel windows of the 1930s, and the whole commercial product has become outdated in performance and appearance.”
Anxious to bypass this approach, Buro Happold employed a young product design graduate from Glasgow School of Art, James Mclean, and seconded him to Glostal’s drawing office in Gloucestershire to work alongside the company’s design and production staff.
With no prior experience of the building industry, Mclean has deliberately steered clear of tackling the patio door as a repetitive building product such as a roof tile or joist hanger. Instead, he argues that it should be seen as a piece of furniture that is touched, manipulated and admired by users. He looked at all the design and manufacturing aspects he could think of – materials, the process of manufacturing and assembly, dimensions, structural stability, thermal performance, ergonomics and aesthetics.
Mclean has pinpointed six features of patio doors that could be radically changed for the better (right). His proposed improvements range from materials – aluminium rather than PVCu – through the manufacturing process – casting, rather than mitering the corners of the frame – to overall dimensions – increasing door heights from 2.2 m to the standard storey height of 2.7 m. In addition, he proposes that a separate aluminium sub-frame should be built into the walls, with the actual frame and preglazed doors added later. A continuous hinge could be extruded as an integral part of the door and frame profiles, and flimsy traditional handles could be replaced by espagnolettes that secure the door top and bottom.
So far, Mclean has developed his ideas using 3D computer models. The next stage will be to make and test prototypes. The plan is to test the market on Glostal’s existing network of trade and customer suppliers next spring.
Tanno acknowledges that Mclean’s proposed enhancements will add to manufacturing costs. But Mclean chips in: “We are cutting things out of the manufacturing process, too. For instance, extruding the hinges as part of the frame and door profiles allows us to leave out the hardware of separate hinges.”
For Tanno, however, the key to marketing the enhanced patio door will be to differentiate it from the run-of-the-mill commercial product. Given the increasing number of architects and carpenters who go to the extent of designing and making one-off patio doors, it could turn out to be more than wishful thinking.
