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Read below description for the facade!
Des Moines Public Library, Iowa, USA
Architect: David Chipperfield Architects
Local Architect: Herbert Lewis Kruse Blunck Architecture
Cladding Consultant: W. J. Higgins Associates
The entire façade of the public library in Des Moines is wrapped in an innovative glass skin incorporating a layer of copper mesh. The cladding provides solar shading, reducing long-term energy costs whilst allowingviews out on all sides.
Manufactured by German based Okalux, the skin of the library is made from a composite triple-glazing system with a slight twist, an expanded copper mesh layer mounted in-between the exterior and middle sheets of glass.
Façade panels with a proprietary aluminium curtain wall frame are suspended on steel brackets from the first fl oor slab. Brackets at ground fl oor and roof level provide lateral restraint only. Each panel is 8.5m high x 1.2m wide spanning the full height of the façade. Okatech sealed glazing units are bonded with structural silicone to the aluminium frames, either as a vision panel with a clear laminated glass inner pane or as a spandrel panel with insulation and an aluminium backing sheet. Both types of panel have the same outer layer of an expanded copper mesh sheet between two sheets of float glass.
The copper mesh is expanded from a flat sheet and the resulting lattice of copper is made up of flat strips bent diagonally at an angle. The sheets are fixed with the strips sloping down towards the outside of the building so in effect they act as tiny solar shades. From the inside the back of the
copper sheet is in shadow so the sheet is quite transparent despite a light transmission of only 31%. From the outside the copper catches the sun and the glare makes it appear opaque. Overlaying glass enhances the copper’s natural sheen and will preserve it from patination.