Field measurement and numerical analysis of wind-driven rain absorption and evaporation on building facades

To investigate the validity of the traditional approach to implement wind-driven rain (WDR) in numerical models of heat, air and moisture (HAM) transfer in building components, under real atmospheric conditions, a new set-up was developed at a test building. WDR intensity, other relevant environmental conditions and the resulting moisture response of the wall to these 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 simulating the hygrothermal response of walls to WDR is very difficult.