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Dismantling sashes is only the first step. To meet strict flat glass recycling standards, storage and transport also matter.
In Winterthur, sashes were lowered by excavator instead of being carried down stairs, and stored vertically in flat containers. A key requirement: the glass had to remain intact to avoid cross-contamination with other materials.

Normally, dismantled windows are thrown into containers together with other materials. At the recycling yard, only about 18% of flat glass is downcycled as container glass, while the majority still ends up in waste incineration plants.
In the pilot project, however, the window sashes were carefully dismantled using simple tools – an essential step towards reuse and proper recycling.

This summer, ZHAW, together with Glas Trösch Group, SWICA, Birchmeier Gruppe and with the support of FOEN, launched a pilot project on flat glass recycling.
At the SWICA building in Winterthur, 375 window sashes were dismantled, stored and separated by material before demolition. The goal: to reintroduce recycled flat glass into the replacement building designed by Adrian Streich Architekten – creating a closed loop for windows.

Congratulations to point0 for winning 4th prize in the housing competition! Windows of Opportunities supported the team on reuse strategies, focusing on window reuse — from integrating reclaimed glass in curtain walls to doubling standardized windows for high thermal performance.

Some of the windows collected in Amden now form the meeting room of co-struct. The timber structure is built from reused wood, and the entire construction is designed for disassembly — nothing is glued.

Soon we will launch a pilot project to recycle old windows into float glass — a first in Switzerland. This will mark a major step toward reducing CO₂ emissions and closing the material loop for building glass.

At the AEC Hackathon in Winterthur, our team developed the foundation of a specialized window database. The prototype includes a feature that automatically evaluates the reuse and recycling potential of windows, setting the stage for a digital tool to support circular strategies in the building sector.

We recently took out several windows and effortlessly removed them in seconds – including the frames. These double-glazed windows from 2020 are in excellent condition. We are currently investigating whether they can be reused in new projects.

Thanks to the InnoCheque, we were able to build our first reusable window prototype.

Come and see the prototype in the Werkstückhalle. It’s open every working day from 9am to 5pm.