Glass is a key material of modern architecture. More than almost any other architectural element, glazed and reflective façades embody the ideals of transparency, modernity and technological progress that shaped the architecture of the 1960s and 1970s. Early coated solar-control glass, widely used in public and office buildings, plays a particularly significant role in this legacy.
To this day, however, such glazing is assessed primarily on the basis of its technical performance. As a result, it is often completely replaced during refurbishment. This not only leads to the loss of historic building fabric: producing new glazing is highly energy-intensive, while glass itself can potentially have a much longer service life. Unless the architectural, historical and material qualities of early solar-control glass are recognised, a characteristic feature of post-war modernism risks gradually disappearing.
Preserve Rather Than Replace
The MAS thesis “Gilded Glass” by Yael Liebetrau therefore examines why and under what conditions such glazing can be preserved. It combines questions of heritage conservation with ecological considerations, exploring how service life can be extended while reducing primary energy consumption and waste sent to landfill.
Based on material and system analyses, the thesis investigates a range of conservation strategies for solar-control insulating glazing. These range from extending the service life of existing units through additional measures to improve their technical performance, to approaches that preserve as much of the original fabric as possible, as well as controlled disassembly and reassembly. The reproduction of glazing using new technologies is also considered. The appropriate strategy depends on the specific architectural, historical, technical and ecological value of each glazing system.
From Case Study to Conservation Strategy
Drawing on existing references and using ETH Zurich’s HIL building on the Hönggerberg campus as a case study, the thesis outlines practical approaches and assesses their technical, ecological and conservation viability. In doing so, it contributes to a more nuanced approach to existing buildings with extensive glazing – and demonstrates the conditions under which preservation and reuse can provide a meaningful alternative to complete replacement.