A resurgence in gold, copper and warm metals is seeing an array of high rise buildings clad in gold and adorned with bright features.
While Dubai, the “City of Gold,” is renowned for a shimmering skyline, gold skyscraper features are beginning to glimmer in other cities including London, Melbourne, Moscow and Singapore.
Mimi Daraphet of Meinhardt Façade Technology in Singapor noted that the trend is largely aesthetic but in some cases, gold coatings can offer thermal performance to the building.
She refers to the “gold crown” atop Melbourne’s Eureka Tower as an aesthetic decision.
The building is Melbourne’s tallest at 297 metres and is named after the Eureka Stockade - a rebellion during the Victorian gold rush in 1854. It is often described as a “shining beacon” in the city.
The gold glass which stretches from level 82 to the roof on level 92 of the building represents the gold rush, with a red stripe representing the blood spilled during the revolt. The blue glass cladding that covers most of the building represents the blue background of the stockade's flag and the white lines also represent the Eureka stockade flag.
“The gold glass is actually a 24-karat gold-coated glass manufactured in Canada,” Daraphet said. “The glass is a double glazed system with a low-e coating that helps to reflect heat in the summer but retain it in the winter.”
The façade doesn’t have to be “gold coated glass” in order to offer thermal protection. Meinhardt, which was behind the façade ensured the entire outer envelope was environmentally efficient.
While specific design details have yet to be revealed, Australia 108, which will soon be Melbourne’s tallest skyscraper at 319 metres, will feature a “golden starburst expression” jutting out of the building.
Architects Fender Katsalidis are expected to utilise similar materials to those used in Eureka for the gold feature at level 72. The “starburst” is an aesthetic choice inspired by the Commonwealth Star on the Australian flag along with a celebration of the sense of community within the building.
Colleagues managing director Mathieu Meur said this approach on both these projects is more common in mature markets, which favour “the more delicate approach of applying gold-coated glass to limited areas of a building (as is the case for Eureka tower) or adopting the even more subtle approach of laminated golden meshes or patterns within glass.”
Gold façades are are also representative of cultural acceptance or a way to communicate success through opulent features.
“For instance, gold-coated glass curtain walls seem to be on the rise in certain developing countries (i.e. Middle East or in second and third tier cities in China), where a golden building may be perceived as the epitome of a successful organisation," Meur said.
This is evident in the recently completed Ahmed Abdul Rahim Al Attar Tower in Dubai which rises 342 metres. Designed by architect Adnan Saffarini, the steel and concrete residential skyscraper features bright gold façade elements on each corner of the rectangular building before it tapers into a generous spine.
In Moscow, the 339-metre Mercury City tower features a copper coloured glass façade which still reflects a golden hue.
Meur said there are three approaches to applying a gold façade. The most common is the application of an on-line or off-line reflective coating to provide a uniform gold appearance to the whole glass. Selected manufacturers even have the ability to apply this coating in a pattern, but this is rather difficult and costly to do.
The second possible technique involves applying a golden ceramic frit to the glass surface, either as a complete coating, or more commonly as a pattern using a silkscreen stencil. This ceramic frit is a solid and opaque coating, so tThe appearance is quite different to the other techniques, which still allow you to see through the glass. This technique was used for the Gold Souk Entrance of Dubai Mall, for instance.
The third approach consists in laminating a golden material within the glass. This can offer a delicate, filigree appearance, but requires exacting production processes in order to avoid or minimise the risk of delamination over time.
Gold is not the only glass colour that can also offer beneficial thermal properties.
“In and of itself, gold coating is reflective, but the spectrum isn’t specifically targeted towards the IR spectrum, which corresponds to the radiative heat coming into the building,” Meur said.
“Gold-coated glass reflects both visible light and heat, to varying extents. However, specific products, in particular on line coated glass, can be combined with low-emissivity coatings to offer the golden appearance as well as greatly enhance thermal performance.”
Additionally, while gold can appear striking on a skyline, there are various degrees of reflectivity which can pose a challenge to architects and the city.
“Gold glass is very reflective particularly if it’s 24-karat gold,” said Daraphet, citing Eureka's solar reflectivity below.
Meur noted that gold coatings can be made more or less reflective, as is the case with other metallic coatings.
“This ranges from less than 20 per cent (as in the One Shenton Way building in Singapore) to 40 per cent or more," he said. “It all depends on the base glass tint and the individual 'recipe' of the coating adopted by the glass processor.”
Both Meur and Daraphet have observed a growing interest in the building codes surrounding highly reflective glass façades following some extreme events including the 20 Fenchurch Street building in London. In late 2013, the building's concave glass reflection caused blinding glare, melting cars and even burning pedestrians.
The heat reflected from the organic curvature of the glass is similar to the effects of burning items with a magnifying glass.
Rafael Viñoly, architect of 20 Fenchurch Street, had the same problem with another of his concave buildings, the Vdara Hotel in Las Vegas that was reflecting the hot Nevada sun onto the swimming pool below.
To combat concerns over glare blinding drivers and neighbouring building occupants, some cities are now implementing building codes to specify a limit to the external reflectivity of the glass or other façade materials.
“The City of Sydney has a cap of 20 per cent external light reflectance in order to reduce glare on drivers and occupants of surrounding buildings," Daraphet said. "Singapore has this regulation as well, but to our knowledge not that many other cities do."
The Adelaide City Council also have a reflectivity rate of 15 to 20 per cent.
Be it gold or glass Rafael Viñolys, reflectivity is a big challenge as more skyscrapers squeeze into cities.
In the meantime, the aesthetics of gold are being enjoyed by architects keen to see their projects shimmer.