The aim of the façade renovation at Herostrasse 5 in Zurich was to renovate a 50-year-old school building in terms of energy efficiency, ecology and design, while preserving as much of the existing structure as possible. The result is a technically optimised, resource-efficient building envelope that reuses a large proportion of the original materials thanks to innovative reuse and remanufacturing methods. During the process, existing 50-year-old parapet glazing was technically evaluated, reconditioned and connected to a new supporting structure using laminar silicone bonding. The ground floor façade was upgraded to a similar extent. The profiled glass was directly recycled. It was joined to form rectangular slats, some of which were used for passive shading or converted into light fixtures. The distinctive skeleton structure with its red enamelled glass balustrade cladding retains its character and proportions. Modern aluminium windows, improved insulation and ventilation flaps with sound-absorbing elements meet today’s comfort and energy requirements. The renovation was triggered by the need to refurbish the façade, which had remained untouched since 1972, and the desire to create a forward-looking example of sustainable construction.