The conversion of the Transa head office in Zurich's Kreis 5 is guided by the motto and principles of reuse. Only what is necessary is demolished and what no longer serves its old purpose is repurposed. The suspended acoustic ceiling made of fiberboard, for example, is cut into panels and stacked in a wooden stud construction made of reused laths to form interior walls. The same with stripped particleboard. Where new meets old, the collision of different materials is deliberately made visible. An existing brick wall with white plaster, is supplemented with a wall construction of three-layer boards - all joined or screwed together - so that it can be dismantled without effort. The surfaces remain raw. Concrete emerges from under the old suspended ceiling, hidden only by the plaster-mounted electrical conduits and wiring when finished. The cement subfloor also remains untreated. Later, second-hand carpets will provide a homelike indoor climate and sound absorption in the offices. Most of the network cables could either be left in place or routed so that they can be re-routed to where they are needed in the new floor plan. The heavy current installations, on the other hand, had to be rebuilt. All technical equipment and installations are now located in an 80 cm deep niche distributed along the approx. 80 m long corridor. Thus, the office and meeting rooms offer as much free space as possible. In order to create a bright and transparent environment, ReUse window sashes from a housing estate in Altstetten are installed as room-dividing elements. The fire doors could also be obtained from a component mine in Winterthur. Photos © Martin Zeller / baubüro in situ ag