There are two re-use projects in Zurich which have reached an advanced planning stage: Graber Pulver are building a recycling centre on the Juch site for the city, while Gigon Guyer are planning the commercial building X for the Swiss Federal Railways. Both projects have ambitious emissions goals and focus on reusing building components – including the loadbearing structure – to the maximum possible extent. In the project on the Juch site steel beams from old halls are being used again. In the SBB building disused rail tracks, overhead cable poles and train windows have been salvaged, along with corrugated fibre-cement sheeting, railings, staircases or radiators. The company Zirkular accompanied both projects. Discussions with design offices and clients gave an insight into the challenges of planning and building with re-use components: processes, timelines and cost estimates can all change. And who is responsible when used material is re-used? This has an impact on design, too — which then becomes “designing by availability.”