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Translucent roofing inspires at German airport

News | April 1, 2018 | By:

The ETFE roof brings natural light into the interior courtyard of the triangular-shaped Lilienthalhaus in Braunschweig, Germany. The offices that surround the space benefit from its brightness. Photos: Hanno Keppel.

Lilienthalhaus, a new building at the Braunschweig Research Airport in Braunschweig, Germany, is named after pioneer aviator Otto Lilienthal. Known as the “flying man,” Lilienthal was the first person to successfully carry out unpowered flights. The designation is fitting; the design of the four-story building embodies the same inventive spirit as the adventurous pilot.

Designed by architect Hartmut Rüdiger of Rüdiger Architekten, the triangular-shaped building bulges out on its three sides, creating a light-filled atrium in the center. The space is open to the public, available for events, exhibitions and lectures.

To create a light-filled environment in the atrium, the architects wanted translucent roofing. They quickly ruled out glass due to weight and fire safety requirements. Rüdiger Architekten looked to membrane experts formTL based in Radolfzell. The company, which specializes in structural membranes, chose transparent ETFE foils for the roof. Like glass, the material offers a high level of UV permeability and translucence, and also satisfies fire protection requirements by making the substructure considerably lighter.

The formTL engineers designed triangular ETFE cushion roofing that measured more than 400 square meters. Because of tensile forces, the atrium roof was built using an extremely light substructure. Steel cables arranged in a rhombic shape and fixed to the perimeter tube around the building form the cushion and carry the loads, making the supporting structure almost invisible.

The triple-layer ETFE roof, which inclines toward the tip of the triangle, was elevated and anchored on top of the concrete structure. In order to reduce heat gain due to sunlight, the outer layer of the cushion was printed with an even pattern.

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