Material Scouting for Urban Mining in the German Building Sector

The transition from a linear to a circular economy in the building sector is essential to protect resources and reduce environmental impacts. A central strategy of circular construction is reusing existing materials, so-called Urban Mining. However, there is a lack of tools for a systematic search for materials for Urban Mining. This paper shows methods for material scouting for Urban Mining in the German building sector. The focus is on searching for buildings about to be demolished so their materials can potentially be reused. The following methods for searching demolition projects could be identified: (1) Internet research, (2) inquiries to institutions and players in the construction industry, (3) city inspection, and (4) public appeal. As part of a case study, methods 1-3 were used to find demolished buildings within a radius of 50 kilometers around a defined point. A total of 15 potential demolitions have been identified. After further research, the demolition plans for eight buildings could be confirmed through contacting the property owners. Permission for an initial inspection has been granted for two of the properties. The inspection of one property showed contamination with asbestos; further use of the structural components was ruled out. Through a student seminar, the urban mining components of the second property were documented. The analysis of the material scouting methods and the case study's implementation showed that procuring reused building components is a time-consuming process characterized by uncertainties. This highlights the need to document used materials and building components in ongoing and future projects. Further, sourcing materials and building components must be simplified to scale construction with reused building components.