Closing the gap between traditional wind-driven rain studies and the performance-based design of building façades: Case study of the Netherlands

Abstract

Over the last few decades, analyses of wind-driven rain exposure on building façades have been conducted in multiple regions. Sometimes, these studies also included the driving rain wind pressure, thereby characterising both critical factors contributing to rainwater penetration into façade materials. However, practitioners typically rely on performance results obtained from standardised watertightness tests to make façade design decisions, even though these tests do not recreate the specific exposure combinations that can occur on each façade. Consequently, there is no quantitative correlation between the traditionally identified exposures and actual façade designs, resulting in pure qualitative choices and poorly optimised designs. This study addresses this issue by correcting the existing methodological deficiencies in a prior calculation procedure, which aims to relate the exposure parameters that the façade configuration withstood during any watertightness test to the expected climate exposures at its design operating conditions. New contributions are presented to enhance the method reliability as well as to reduce calculation effort and reliance on exhaustive weather data. The various climate parameters required to establish this relationship were analysed and tabulated for the Netherlands, enabling a truly performance-based design of façades to resist rainwater penetration throughout the country. Different methods of implementing this procedure, according to the availability of weather data, were also compared for façade case studies located in Amsterdam and Maastricht.