Lightweight insulating glass unit: Fid-Bau Portal

Lightweight insulating glass unit

Joos, Pascal / Willareth, Philippe / Wüest, Thomas

With the inscription “The Materials are Iron and Glass”, the medal from the 1851 World’s Exhibition also aptly describes the Crystal Palace and the botanical gardens of the University of Bern, which were built around 1860. The filigree steel structure, which is protected as a historic monument, must be preserved. In order to ensure the load-bearing safety of this structure with as few reinforcement measures as possible, the weight of the roof glazing is reduced to an absolute minimum. A variant study of possible insulating glass units is carried out within the framework of the building physics and monument preservation constraints, as well as considering the radiation that is important for plant growth. The further development of glass refinement and the resulting improvement in glass properties play a decisive role in this. Lightweight and highly efficient chemically strengthened 0.7 mm thin glass and 4 mm thick low-E coated thermally toughened glass are combined in an insulating glass unit. A test concept was developed to test the load-bearing safety and personal safety of lightweight insulating glass and chemically strengthened glass. The strength, the influence of surface damage, the fracture pattern as a result of various loads and the residual load-bearing capacity were analysed. The results obtained fulfil the assumption that the impressive deformation capacity of the glass results in a high level of safety without being a safety risk. A hail resistance class 3 was achieved by firing a hail cannon. The radiation transmission of the entire lightweight insulating glass unit was measured using a spectrophotometer. A light transmission of 82% and UV transmission of 52% were achieved. Work has already begun on the refurbishment measures and the designed glass will be installed in the middle of next year.