Assessing Renovation-Avoided Carbon Emissions: A Comparative Life Cycle Assessment and the Influence of LOD on a Building Use Conversion Project

Abstract

Renovating existing buildings has emerged as a decisive means of mitigating environmental impacts from buildings. However, estimating life-cycle environmental impacts remained challenging, as rapid early-stage assessments often differed substantially from results from detailed models. This study conducted a comparative Life Cycle Assessment (LCA) of an existing building that underwent adaptive reuse, comparing embodied carbon savings against a demolition and new-build scenario. It isolated the intrinsic material burdens and end-of-life processes of different design scenarios, offering insights into the environmental implications of choosing renovation and adaptive reuse versus demolition and rebuilding. The results demonstrated a 68% reduction in emissions when renovation was chosen and highlighted the relative contributions of different building stages and materials. Significant carbon savings of more than 2,500 metric tons CO₂e were measured, stemming mainly from the retention and reuse of high-impact structural materials such as concrete and steel, which together accounted for more than 93% of the total savings. This study also assessed the impact of Level of Development (LOD) on LCA results, demonstrating that a highly detailed building model at LOD 350, compared with LOD 200, produced a 45.8% variation in results. This contribution highlighted the importance of clearly defining LOD levels when using LCA results to support carbon-reduction decisions. Ultimately, this study provided an empirical case-study benchmark for future LCA studies on adaptive reuse projects, and offered actionable insights for architects, engineers, and policymakers seeking to prioritise adaptive-reuse strategies and appropriate LOD definitions as pathways to accurately meet carbon-reduction targets and support a net-zero future.