Resilience in building life cycle assessment: a critical review and framework for time-integrated functionality

Life cycle assessment (LCA) is increasingly used to evaluate the environmental performance of buildings under climate-related hazards. However, current approaches assume constant service delivery over time and represent disturbances primarily through additional environmental burdens (e.g., repair and replacement), limiting their ability to capture resilience. This study aims to examine how resilience dimensions are currently operationalized in building LCA and to propose a methodological framework that enables their full integration. A systematic review of 40 original LCA studies spanning four hazard types (heat, flood, wind, and seismic) reveals that while resilience is commonly defined in terms of functionality loss and recovery, LCA studies largely neglect variations in service delivery over time and concentrate on robustness, particularly in preparation and recovery phases. Other dimensions (rapidity, redundancy, and resourcefulness) remain systematically unrepresented due to static functional units and constrained system boundaries. To address this limitation, this paper introduces a resilience-extended LCA (RES-LCA) that redefines the functional unit as time-integrated functionality, representing the cumulative service actually delivered over the building life cycle under disturbance. This reformulation captures both the magnitude and duration of performance loss and establishes a logical basis for extending the LCA inventory to include compensatory service flows during periods of impaired function, post-event improvement works, and avoided environmental burdens attributable to resilience investments. This paper demonstrates that the commonly assumed trade-off between resilience and sustainability is, in part, an artifact of conventional LCA formulations that undercount the environmental costs of service disruption.