Integrating circularity and lifecycle assessment for building renovation: A multicycle framework

There exist different circularity indicators and lifecycle assessment (LCA) methodologies to calculate resource efficiency and environmental impacts of the building sector. But they largely operate within single-lifecycle boundaries and lack a consistent approach for assessing material across multiple lifecycles in existing buildings. This study addresses this gap by adapting the Material Circularity Indicator (MCI) assessment approach for the renovation of buildings (MCI RENO ), which accounts for successive lifecycles of the materials generated from the renovation. The MCI RENO is integrated with the Circular Footprint Formula (CFF) to provide a methodological operational unified framework for evaluating circularity and environmental impacts. Using a systematic selection process, seven end-of-life-cycle allocation methodologies were compared to identify the CFF's point of integration with MCI RENO . In the framework, the MCI RENO incorporates extended lifetimes and reuse potential, while CFF allocates environmental burdens and credits across multiple loops using standardized factors. The framework is validated with an empirical example of façade brick using seven scenarios and probabilistic uncertainty analysis of key parameters. The analyses reveal that material recoverability drives the degree of circularity and is sensitive towards varying scenarios. Similarly, environmental outcomes remain scenario-dependent and primarily driven by avoided virgin material production. The combined results are sensitive to contextual and scenario-specific assumptions. The approach offers a structured framework to jointly evaluate multicycle circularity and environmental impacts of inert materials. Future research across heterogeneous materials and renovation complexity can strengthen the robustness of the proposed framework.