portfolio of window profiles and its experience in developing special solutions. In close cooperation with MTZ-Metalltechnik Zitzmann and daylight planner Dr Helmut Köster, the architects and the Forster team developed [...] RETROSolar Gesellschaft für Tageslichtsysteme mbH, Kirn Architecture: SSP AG, Bochum Metal fabrication: MTZ Metalltechnik Zitzmann GmbH, Oerlenbach Client: University of Cologne Photography: Jens Kirchner,