GIS-based application to calculate directional wind-driven rain exposure on residential buildings at an urban scale: The case study of Zaragoza, Spain

Abstract

Rainwater penetration is a key risk factor for the durability, hygrothermal performance, and habitability of built environments. Rainwater deflected by wind action (wind-driven rain, WDR) constitutes the primary source of water penetration for building facades. Therefore, characterizing their exposure to WDR is essential to have information that substantiates decision-making. However, this exposure has not yet been characterized at extensive urban scales. This research proposes an automated and replicable GIS-based method to assess the directional WDR exposure at a comprehensive urban scale. The method is based on the analysis of cadastral data and hourly weather records of rainfall intensity and wind velocity gathered over ten years. The directional WDR exposure throughout a mid-size European city (Zaragoza, Spain) is characterized as a case study. The detailed maps show that the WDR exposure ranges from 45.95 to 285.77 (mm/yr) between the different facades of the city. This variability in the built environment, caused by factors such as the urban configuration, local topography, and height and orientation of each facade, confirms the need for a functional urban characterization of WDR exposure. The proposed method can contribute to providing an automatized data-driven urban analysis to better establish urban strategies and renewal policies at different scales in cities, allowing for improving the resilience of the built environment against rainwater penetration.