Table 7- Natural materials in cladding weight
Reusable materials
The concept of“ reusable material” is controversial and still much discussed. At the end of the cycle of use of a material the scenery can be very different, depending on the material itself. Concrete can be recycled, but just an amount of about 20 %, but the biggest part of concrete is“ down-cycled” at the end of life into new products. A small amount is destined directly to the landfill. There is no way to re-use a concrete frame or a part of it, this is the reason why is not convenient to use concrete in a temporary building. Wood is subject also to some other end-of-life scenarios: it could be incinerated or re-used. A big percentage of used wood must be moved to landfill, but the reuse and the recycle process required a small amount of energy, making the wood one of the material most suitable to support sustainability. Steel can be recycled with a very high percentage and a good part of the not-recycled part can be reused. In this way just a percentage of about 1 % must be moved to the landfill, even if the recycle process requires a lot of energy. The reuse and the recycle processes should reduce or eliminate waste and the request for primary resources. It’ s possible to obtain these goals with all materials, but while designing a temporary structure is surely attention-worth an analysis of the end-of-life scenarios of materials employed in the project. Depending on the size of structural elements, the architectural boundaries and the properties of available materials a choice must be made: for example steel is 93 % recyclable but with a big amount of energy and is very heavyweight, so if it’ s not available near the construction it could be a bad choose. Otherwise wood is recyclable or reusable with a smaller percentage but, if the construction is designed to be easily moved, can be the most sustainable choice.
The pavilions of Expo 2015 in Milan 485