Improved assessment of wind-driven rain on building façade based on ISO standard with high-resolution on-site weather data

Abstract

Wind-Driven Rain (WDR) is one of the major moisture sources that cause building envelope failures. The quantity and spatial distribution of WDR are important considerations for durable building envelope designs and are essential boundary conditions for hygrothermal modelling. Within a comprehensive research program of quantifying WDR exposure of buildings and the effectiveness of overhang on reducing WDR wetting, a six-storey building located in Vancouver, Canada was instrumented for field WDR measurements. One of the challenges in field WDR measurements is the validity of on-site wind measurements. The accurate measurements of on-site wind conditions are essential for correlating WDR on façade with on-site weather conditions and for generating the spatial distribution correction factor required in the semi-empirical WDR models. This paper focuses on discussing the procedure necessary for proper on-site wind measurements for quantifying WDR on façade based on field and wind-tunnel measurements. The proper procedure to calculate the spatial distribution correction factor, namely wall factor according to ISO standard, and its impact on the accuracy of the ISO model is also discussed. The accuracy of ISO model can be significantly improved by using more detailed wall factors calculated based on high-resolution on-site wind and rain measurements.

Representative meteorological data for long-term wind-driven rain obtained from Latin Hypercube Sampling – Application to impact analysis of climate change

“…An average driving-rain index for free field conditions across all wind directions, DRI ff , and another similar index normal to an imaginary wall facing west, DRI ⊥ , can be defined as in Eqs. ( 6) and (7), respectively [35]:…”

“…In past research, both field and wind-tunnel measurements are used to understand the interaction of raindrops with building surfaces and to validate and improve various WDR modeling approaches [3][4][5][6][7]. Hygrothermal simulations of porous building facades are commonly performed using time-resolved WDR intensity as a boundary condition obtained from semi-empirical models [8][9][10] or from computational fluid dynamics (CFD) simulations [11][12][13].…”

Assessment of wind-driven rain (WDR) on buildings in an urban area: comparison of different CFD frameworks

“…The on-site meteorological parameters, i.e. wind speed and wind direction, measured on the top of the test building (4.6 m above the mechanical room), were compared with two nearby airport weather stations, known as Vancouver Sea Island and Pitt Meadows stations, to evaluate the reliability of the equipment [7].…”

“…Wind-tunnel measurements were carried out [7] and used for validation in this study. Figure 1b shows the 1:400 scale model of the test building and its surroundings, located in Concordia University's Atmospheric Boundary Layer (ABL) wind-tunnel.…”

Estudo de caso do desempenho de estanqueidade à água de argamassas e hidrorrepelentes - Parte I

“…Nas fachadas, de acordo com Chew e Tan [11], a degradação decorre sobretudo da ação conjunta da chuva, vento, variações térmicas e poluentes atmosféricos e biológicos, quando a água da chuva escoa por meio da superfície vertical, lavando a fachada e depositando agentes agressivos. Para Ge et al [12] a chuva associada ao vento é a principal fonte de umidade que afeta o desempenho higrotérmico e a durabilidade das fachadas, sendo que a quantidade e distribuição é afetada pela velocidade e direção do vento, intensidade da chuva, ângulo do vento, geometria do prédio, localização das fachadas e topografia do entorno.…”