黑洞社区

Developers of retail schemes, high-rise office towers and Olympic Games all want the same thing: an iconic building that will force everyone who sees it to wonder how the hell they built it. But Andrew Hall, director at Arup Facade Engineering, suggests that the question specifiers should be asking is: 鈥淲ho the hell is going to build it?鈥� According to Hall, the demand for cladding that covers geometrically complex surfaces is high, and the number of firms that can do it is falling.

The principal factor here is the demise of Schmidlin, the Swiss cladding firm that specialised in such landmark projects. In its absence, the British cladding market is short of the skills needed to create complex bespoke facades. 鈥淚n the UK, we鈥檙e in a very luxurious position with clients allowing us to be innovative,鈥� says Hall. But for how much longer if market limitations push up prices? Could iconic architecture become less attractive in these circumstances? Hall says: 鈥淚t might be that small significant developers will walk away from these projects because of their extreme complexity.鈥�

A significant architectural cladding trend is for macro-faceted buildings such as the proposed 拢700m Trinity office complex designed by Foreign Office Architects for developer Beetham in Aldgate, just outside the City of London. Alejandro Zaera-Polo, a director at the practice, says the idea was to develop a crystalline concept through a 40,000 m2 fully glazed envelope. The project hasn鈥檛 gone to tender yet, but it will be interesting to see which manufacturer will produce the large panels. Zaera-Polo admits there are few firms that will be able to make the sophisticated shading system for the Trinity scheme. The architect says that to comply with Part L of the 黑洞社区 Regulations, a shading system is the most appropriate option. He is interested in using unitised systems that combine full glass enclosure and areas of different materials attached to the external glazing, but these haven鈥檛 been much exploited yet.

How the City of London would look with Foreign Office Architects鈥� Trinity Office Complex, just below the Swiss Re tower

Geometric challenges

As far as more traditional methods of construction are concerned, Hall thinks that for geometrical schemes that comprise complex glass and curvature, specifiers should try to integrate the manufacturing process into the 3D modelling. 鈥淲hen manufacturers are bidding for the facade, they should understand the cost implications,鈥� he says.

Meanwhile, Make Architects鈥� 拢4m conversion of a disused 24 m high water tower to an office development in Huntingdon proves that an ambitious cladding system can be achieved using the standard products. Make director James Thomas says: 鈥淏y pushing the boundaries of standard cladding systems within their standard warranties we鈥檝e been able to create a cost-effective office and an iconic symbol for the Huntingdon area.鈥�

The architect鈥檚 brief was to design a three-storey glazed lighthouse beacon on top of the 1935 water tower. To comply with Part L, insulated gold panels have been incorporated into the glazing of both the upper and lower office spaces to lower the cooling load. Thomas specified Sch眉co鈥檚 SSG FW50 capless system, which slopes outwards for the upper part of the tower, and which is intended to evoke a lantern. The southern facet of the upper office structure will also incorporate an abstract pattern of crystalline PV cells by PV Systems incorporated into the interlayer of the double-glazed units to provide shading and an estimated 1440 kWh of electricity annually. The mix of insulated, photovoltaic and double-glazed panels varies around the tower according to the solar gain.

For the south-western elevation of the lower office building, the architect specified glass-reinforced cement panels from Fibrecon to match the colour of the existing concrete tower. Thomas says he chose these panels because they were lighter, better insulated, thinner and faster to assemble than a concrete wall would have been.

Another efficient way to solve the shortage of complex cladding materials is, according to Hall, to adopt a more global procurement strategy with manufacturing plants being set up in countries such as Canada, the Middle East, South America, India and China (where Permasteelisa already has a manufacturing plant).

Make鈥檚 golden tower of Huntingdon, created using a derelict water tank and an off-the-shelf cladding system