Publication
Building Replacement (BR), involving demolition and immediate reconstruction on the same site, is a key urban strategy with major environmental impacts, including waste generation, resource depletion, and increased embodied carbon emissions. Despite its importance, research on BR remains limited, particularly in terms of quantitative evidence. This thesis examines BR patterns, material flows, and carbon impacts, analyzing 1,018 replacement projects and 6,115 buildings in Zurich from 2001 to 2019.
The first work uses bigraph analysis to investigate shifts in BR patterns, comparing demolition and new construction groups across urban and building scales. Findings indicate that BR constituted 56% of total building demolitions and 11% of the existing building inventory by volume during the studied period. The main type of BR shift is observed in the residential building replacement (RBR). This work is the first to distinguish densification intensities across 64 shift types, categorized by use. Substantial densification and compactness enhancement have a decisive impact on demolition decisions, underscoring the need for policymakers to reassess these shift requirements.
The second work introduces a novel bottom-up approach to model large-scale building stock and quantify their structural material use and embodied carbon emissions (A1-A3 phases). Based on the inverse distance weighting, an advanced similarity-weighted (ASW) interpolation method incorporating Softmax is proposed. This method preserves the heterogeneity of model data, addressing the limitations of oversimplification and homogenization that are common in archetype-based approaches. Results show that BR involves structural components totaling 4,688,387 m3 in volume, 10,272,131 tons in mass, and 1,390,126 tCO2eq in embodied carbon emissions. Slabs and walls are the primary contributors, with concrete being the predominant material, accounting for up to 99% of the structural mass in new buildings. Multi-residential and office buildings comprise 92% of new structural concrete use.
The third work focuses on Residential Building Replacement (RBR). This work assesses the carbon payback time (CPBT) of these RBR projects compared to RN (Refurbishment and New Construction) and RO (Refurbish Existing) scenarios. This work extends consequential replacement life cycle assessment (CRLCA) from individual cases to the stock level, incorporating a range-bound analysis. Results show that: for Zurich's 335 RBR projects with volume-weighted average decision year of 2014.3, the CPBT occurs before 2036 on a per capita basis and before 2030 on a per area basis; across all simulation configurations, BR consistently exhibits higher cumulative carbon emissions than the other two scenarios for decisions made post-2019, whether measured per capita or per unit area; and per capita metrics yield a later CPBT for BR than per-area metrics in Zurich, showing that these metrics can lead to differing conclusions based