Luca Zanier, Franz Rindlisbacher
The machine hall is one of the first completely welded steel frame structures in Switzerland. Hot design technology—a simulation and verification method sometimes used in aircraft construction—shows that the hall's supporting structure still meets today's requirements and can be left in its current condition. The situation is different for the glass prism roof that characterizes the machine laboratory: due to leaks and increasing deterioration of the structural condition, the roof was additionally covered over time and a wooden ceiling was installed from the inside as early as the 1950s. The gradual dismantling of the roof has revealed 168 modular elements, each containing 65 or 78 glass blocks. There are eight different types of glass blocks distributed across the entire roof. The thickness of the glass elements found is only one-third of the height of a modern glass block element, which is 24 cm due to building physics requirements and consists of two glass blocks and an interstitial space filled with noble gases. Copies modeled on the historic glass prisms are embedded in the lowest level of the double glass blocks commonly used today. This preserves the filigree appearance and the associated effect of the original roof. The restoration of the glass prism roof, which is so characteristic of the machine laboratory, in accordance with current standards represents an important milestone in the renovation work, as the natural incidence of light and the resulting light guidance through the building were part of Otto Rudolf Salvisberg's overall spatial program.
Itten+Brechbühl AG
