Glass Roof for the Hippo House at the Berlin Zoo

The Berlin Zoo, open to the public since 1844, is Germany's oldest zoological garden. Following World War Two, a new hippo house was built in 1956. This compound has grown outdated both technically and structurally and is being replaced by a glass-covered structure with observation windows below the waterline. The glass roof has been designed to cover two circular pools, one about 21 m in diameter for pigmy hippos, and the other about 29 m diameter for the standard hippopotami. The challenge of the Berlin Hippo House was to find the mesh geometry for two spherical domes, with a smooth and continuous transition between them that could be covered with flat glass panels, since the four corners of each mesh lie in a plane.