International London-based architects CallisonRTKL in collaboration with Melbourne-based architects The Buchan Group, structural engineers Atelier One and facade specialist seele have created a breath-taking freeform gridshell structure constructed from steel and glass at the Chadstone ‘The Fashion Capital’ in Melbourne, Australia. The gently curving roof appears to rest on the building like a delicate shawl. In reality the construction’s domed and vaulted steel elements, which arch over the two-storey retail space of what the operators call 'Australia’s pre-eminent shopping' weigh 500 tons.
Every element is unique
Some 2,670 panes of Schollglas GEWE-therm 4SG insulated glass equipped with external sun protection regulate the amount of natural light entering the building; its heat insulation and protection against the sun. Every pane has a different shape and dimensions – no two trapezoidal or triangular panes are the same, not even in terms of their surface shape. The panes, ranging from 1.2 to just under 8 square metres in size, have all been modified to fit the curving construction design. To create it, the experienced facade construction team used an on-site bending procedure to fit the glass elements, initially manufactured as flat units, into the curved profiles. This ensured that the 'cold bent' glass took on exactly the spherical geometry required for each frame. It was possible because, despite the overall roof construction’s expressive wave-like shape, each individual pane has only a minimal curve. Such a construction method is a challenge even when using single-glazed elements. In this case it required the bending of two-layer insulated glass from Schollglas, consisting of one pane of toughened safety glass and one layer of laminated safety glass made from two panes of annealed glass.
Kömmerling Chemische Fabrik/Aaron Pocock
In combination with the argon-filled interspace, the units were approximately 39 millimetres thick and were adjusted to match the curvature of the supporting construction during installation.
4SG optimises function and design
For its GEWE-therm sun protection and thermal insulation glass, Schollglas used 4SG edging with a thermoplastic spacer specially developed for structural glazing facades. The spacer that can be formed flexibly but almost without stress allows a water vapour-impermeable, gas-tight edging seal which ensures both physical and chemical adhesion and thus an optimum connection between the glass and the silicone secondary sealing. In combination with the 4SG spacer, this delivers edges which are permanently sealed and ‘warm’ in energy terms, particularly in the case of applications involving highly challenging pane geometry or where glass is expected to distort.
Precisely planned delivery and assembly
The project’s logistics also presented the companies involved with major challenges. After completion, each construction phase was glazed in stages – based on a precisely planned-out manufacturing and delivery chain. The window panes, manufactured in Germany in specific shapes and dimensions, were shipped to Australia by container. To make this possible, they were packed extremely carefully in solid-wood seaworthy containers using individual pane protection and ShockWatch devices.
seele
The expressive, distinctive glass design is a highlight of the Chadstone shopping centre, not only in terms of urban planning and architecture. In addition to this, the heat insulating roof glazing in combination with the large amounts of natural light inside the building but its ability to prevent overheating also delivers impressive ecological added value. Greenhouse gas emissions have been reduced by 61 per cent compared to other shopping malls. This has been rewarded, among other things, with a 5-star sustainability rating from the Green Building Council of Australia.
