The building as such or any additional built structure can be designed circular. In this way, the material is stored for its life cycle and afterwards recovered. The real building application is not so easy as in theory. Finding these circular materials and also working with craftsmen that know how to work with these materials is a challenge by its own. The movement "built positive" supports the different steps. In bamb2020.eu and soon in houseful.eu one can find a very good overview of circular building processes.