Multiscale pattern analysis of building replacements in Zurich from 2000 to 2019

Building replacement (BR) – i.e., the demolition of existing structures and subsequent construction of new buildings on the same site – is often understood as a necessary urban planning strategy despite significant environmental implications regarding solid waste generation, raw material depletion, and embodied greenhouse gas emissions. Besides, BR may also be considered an effective form of urban mining. Yet it has not been adequately studied in academic literature. Current studies often adopt a simplified ‘black box’ approach that overlooks the intricate internal mechanisms and fails to capture the interconnected material flows within the building stock. To address these gaps, this paper utilizes descriptive statistics and bipartite graph analysis to examine the transformation patterns of BR across three spatial scales in the city of Zurich. The analysis encompasses 1,018 replacement projects involving 6,115 building units from 2000 to 2019. By comparing the characteristics of demolished and newly constructed groups, the study reveals insights into the dynamic nature of BR. From a broader perspective, the combination of the various heterogeneous BR-related findings in this paper highlights the need to evaluate the application of circular economy principles to large building stocks with a more nuanced understanding of building stock dynamics over time.