The recent announcement of this year’s winner of the Carbuncle Cup – an architecture prize awarded annually by the Building Design magazine for the worst new building in the UK in the previous 12 months – has redrawn the attention of the general public as well as that of the architectural circles to some of the dangers that the use of highly reflective façades can pose on the surrounding urban areas.
The recipient of the 2015 Carbuncle Cup is 20 Fenchurch Street, a 160-metre skyscraper in London designed by Rafael Viñoly and completed in 2014. Nicknamed “Walkie Talkie” because of its distinctive shape, the building has also been dubbed "Walkie-Scorchie" and "Fryscraper," due to the solar energy problem observed in 2013. While still under construction, it had been discovered that on sunny days the concave glass façade acted as a mirror concentrating sunlight onto the streets to the south. The glare translated into extreme street-level temperatures, up to 117°C, damaging parked cars and burning the doormat of one nearby shop.
This may be an extreme example of an architectural flaw related to the use of highly reflective materials in building façades, but precisely because of that also one emphasising the need for great caution when opting for mirror-like building exteriors. 20 Fenchurch Street is covered in glass, but there are other materials having similar reflective properties. One of them is stainless steel which, when polished to the highest possible level, can be used as a shiny building dress.
A recent architectural project successfully employing stainless steel as façade material is the Len Lye Centre in New Plymouth, Taranaki, New Zealand. Designed by Patterson Associates, this eye-catching museum is dedicated to the pioneering filmmaker and kinetic sculptor Len Lye (1901–1980). The mirror-like exterior echoes Lye’s use of stainless steel in many of his sculptures, thus serving as a lasting tribute to this internationally renowned and visionary artist. To realise their vision, however, the architects had to take into consideration a number of important factors. As they explained for a recent Stainless Steel World News article, there was much discussion regarding the material specification, particularly in terms of corrosion resistance and glare. Since the building is located very close to the west coast of New Zealand, the smoothest type of marine-grade stainless steel was selected in the end, to resist corrosion. The second major challenge was also successfully overcome: the architects mitigated the effect of glare by curving the stainless-steel curtain in a convex fashion, to disperse the sunshine. The resulting concave zones are on a very tight curve, approximately 360mm, so the hotspot zone is fairly close to the building. To reduce the amount of solar energy reflected off the surface, the architects had explored the merits of perforating the stainless steel panels, but in the end the risk of corrosion around the perforations was considered too great. Considering that no heat-related or any other problems have been observed so far, it is safe to say that the architects managed to fulfil their artistic vision without sacrificing safety and durability.
Highly reflective façades, including those of stainless steel, are therefore in no way problematic per se, as the example of 20 Fenchurch Street might falsely suggest. On the contrary, they offer one of the most visually attractive architectural solutions for building exteriors, provided that their aesthetic appeal is not undermined by flawed designs causing excessive glare, solar energy or other functional problems.
Header Image and photo by Patrick Reynolds, courtesy of Patterson Associates