Unitised curtain walling is by no means the new technology you think it is (22 October, page 76).

The modern skyscraper would never have been constructed without it and to suggest that unitised curtain walling is primarily an invention of modern-day European manufacturers is a bit of an oversight.

Unitised curtain walling systems are the past and most certainly the future for glazed facades. Unfortunately, many specialist European facade contractors have instilled the myth among UK architects and contractors that unitised facades are complex and should only be installed by experienced specialist contractors. If that were the case, it would blow a hole in the argument for off-site manufacture. Unitisation should simplify the process and, in my view, it does. With manufacturers now supplying off-the-shelf unitised systems, the market is open for rapid growth in off-site manufactured glazed facades.

Neil Calvert, Sapa Building Systems, via email