Wood

Wood is the only biological material used for building purposes. It stands out from other materials not only because it is a naturally renewable material (which the other materials are not), but also because it is liable to decompose when basic circumstances are not ensured, because it features an extreme anisotropy due to its fibrous structure, because its microscopic structure is extraordinarily complex, and because it is subjected to strong, difficult to control deformations under diverse influences. In terms of sustainability, it has a virtually unchallenged record as the material with the most favourable environmental footprint and a renewable material which, given a sustainable stewardship of forests, can be made available with no restrictions whatsoever.