Assessing the building façade vulnerability to multiple hazards

Building envelope plays a critical role in ensuring the overall functionality, energy efficiency, and safety of buildings. Due to the exposure to climatic conditions and extreme natural events, building envelope components deteriorate faster than other building components. Beyond long-term performance issues, degraded façade components pose a significant risk to their surroundings directly related to the façade's vulnerability: the more vulnerable its components, the greater the probability of their detachment, and consequently, the higher the risk to people. Assessing this Building Risk, as a consequence of the façade vulnerability, should represent a primary concern in ensuring urban safety. However, this topic is not thoroughly explored in the scientific literature; moreover, methodologies to evaluate the façade vulnerability to multiple hazards are missing. To fill this gap, this paper proposes a methodology for assessing building façade vulnerability to multiple hazards. The study determines the propensity of façade components to suffer damage when exposed to hazards by combining their two primary drivers of damage: technical characteristics and degradation. Both drivers are evaluated individually, then combined using a quantitative formula to assess the façade vulnerability. The methodology is tested on existing façades located in the Campi Flegrei area, a significant multi-hazard context. The methodology provides a structured approach to vulnerability assessment that can be adapted to new risk scenarios and contexts, ensuring replicability and flexibility. Results contribute to conceptualising and implementing the RETURN project virtual testbeds, enabling the development of “what-if” scenarios to support risk-informed adaptation planning and Disaster Risk Management strategies.