Building the future using the existing building stock: the environmental potential of reuse

Immense amounts of natural resources are consumed and processed by the construction sector every year resulting in a significant climate impact. In return, the resource and environmental value of these resources is lost due to the vast amounts of construction and demolition waste (C&DW) that is down-cycled. Thus, the potential of transitioning the construction sector from a linear to a circular economy (CE) are expected to be significant. In Denmark, C&DW make up 40% of all waste. Although 88% of the C&DW is recycled only 36% is upcycled (i.e. recycled with an equal or higher quality than the original resource) while 52% is down-cycled (e.g. crushed for road filling). More recently interest in direct reuse has increased as better way of exploiting the remaining technical service life of the materials and retaining the inherent value of the materials and avoid environmentally heavy material processing. In coming years, a large number of homes on Denmark’s ‘ghetto list’ (i.e. socio-economically disadvantaged residential areas) corresponding to 1,360,300 m² are to be demolished. At the same time, a large number of new buildings is to be built in the same affected areas. The Resource Block project seeks scalable reuse solutions that can link the large amount of resources in the existing buildings to be demolished with the need for resources to build the new buildings in these areas. On the basis of a life cycle assessment (LCA), the paper at hand assesses the environmental benefit of the reuse solutions found from the Resource Block project. The results show that reuse of these elements may on average potentially save 49% of the new buildings’ greenhouse gas emissions compared to building solely with virgin materials depending on the availability and degree of reuse and which types of virgin materials the reuse is combined with.