Experimental and numerical analysis of the hygrothermal response of walls to wind-driven rain

To investigate the validity of the traditional approach to implement wind-driven rain (WDR) in hygrothermal building envelope models, under real atmospheric conditions, a new set-up was developed at a test building. Reference wind speed and direction, WDR intensity, outdoor air temperature and relative humidity and the resulting moisture response of the wall to these environmental conditions (both hygroscopic loading and WDR) were simultaneously measured. The whole measurement data set was used for validation. Large differences between the measurement and simulation results were found and possible causes discussed. It is concluded that many influencing parameters interact, and that therefore precisely predicting the hygrothermal response of walls to wind-driven rain is very difficult.