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‘Cologne Triangle’ defies laws of aerodynamics and transparency

Safety glass with SentryGlas® high strength interlayer Facade glass made with strong SentryGlas® helps meet high wind loads, and is about 20 percent thinner than traditional laminated glass.

Structural properties of SentryGlas® make facade thinner and lighter.

The ‘Cologne Triangle’ by architects Gatermann + Schossig is a striking yet slender 103 m-tall office tower wrapped in glass that seems to defy traditional laws of aerodynamics and transparency.

The tower’s south facade, which is subject to particularly demanding wind load and solar requirements, is double glazed to incorporate laminated glass with DuPont™ SentryGlas®  structural interlayer.

Josef Failer of glass laminator Flachglas-Wernberg said: "The south facade of the Cologne Triangle owes its great transparency and feeling of lightness, combined with outstanding post-breakage strength, to an entirely new point-fixed glazing system incorporating 2,500 m2 of laminated glass with SentryGlas®, designed by Flachglas-Wernberg, which looks almost ‘frameless’ to the eye. Using laminated glass with SentryGlas® interlayer, which Flachglas has trademarked SiglaPlus®, we have successfully met the structural strength requirements of the architects and engineers, requiring extremely high wind load performance, with a solution that is about 20 percent thinner than traditional laminated glass.

"Key to this new-generation architectural laminated glass is the outstanding post-breakage performance of SentryGlas® structural interlayer. In addition to its rigidity, the structural interlayer also contributes to the transparency of the façade because of its excellent edge stability, which means no delamination and no discoloration." The glazing consists of 6 mm fully-tempered Pilkington Optiwhite® glass + 1.52 mm SentryGlas® + 8 mm fully-tempered Optiwhite® glass. Flachglas worked with façade engineer Schmidlin Deutschland AG of Berlin to complete the Cologne Triangle’s facade.

Gatermann + Schossig principal, Professor Doerthe Gatermann, told LGN: "The tower takes the form of a triangle with three curved sides. Our concept was to create a contemporary building for the city of Cologne. The city authorities love the very modern form of an ethereal glass tower, and they hope that it will become a new Cologne landmark."

Professor Gatermann continued: "The Cologne Triangle’s unusual glass form means that city dwellers and visitors alike still have great, uninterrupted views of our city’s majestic cathedral, which lies just across the river; it has also enabled us to create an office tower that is highly energy efficient. The glass facades use the sun’s energy to help heat the building in winter.

"As well as providing significant structural strength to the glass façade and helping the Cologne Triangle to obtain planning permission in the face of significant wind load requirements, the laminated glass with SentryGlas®  used in the south façade is intrinsically clear; people inside the office building benefit from great views over the cathedral and the city."

This is the first installation of a laminated glass facade with SentryGlas® on a new building in Germany - and in Europe. In 2004, Flachglas also used a two-sided supported facade using SentryGlas® for the 5,000 m2 refit of a corporate headquarters in Hamburg, working with facade engineer Strabag AG.