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