ERMESS: extreme wind risk assessment for building portfolios

The increasing attention of stakeholders to extreme winds impacting the built environment is driving towards the adoption of probabilistic risk assessment methods, which aim at the stochastic modelling of three main risk components: hazard, vulnerability (or fragility), and exposure. Taking from seismic risk assessment, the hazard is typically expressed in terms of exceedance rate of an intensity measure of the natural event, usually related to wind speed, and the risk metric is the expected annual loss or the exceedance rate of the loss. On these premises the extreme wind risk assessment software, ERMESS, has been developed for risk assessment for portfolios of buildings. It integrates recent global- and regional-scale hazard maps for extreme wind events, that is, cyclones and tornadoes, and a database of more than five-thousand building- and component-level wind vulnerability and fragility functions from the literature. A procedure to develop building-level fragility models, based on existing component-level fragility functions, was also developed and embedded in ERMESS. Finally, the exposure (i.e. consequence) models are based on information provided by the insurance industry. The paper illustrates the software by means of proof-of-concept applications that show how ERMESS can be effective in wind risk assessment.