Wind-driven rain assessment on buildings using climatic data sets: What time resolution is needed?

This paper provides an analysis of the required time resolution for meteorological input data (wind speed, wind direction, and horizontal rainfall intensity) to obtain accurate wind-driven rain (WDR) calculations. Earlier work has indicated that the use of ten-minute input data can provide accurate results, while the use of arithmetically averaged hourly data can give rise to significant underestimations in the calculated WDR amounts. This paper builds on this earlier work by providing an investigation of the parameters that determine the required time resolution: (1) the averaging technique, (2) the building geometry and the position at the building facade, and (3) the type of rain event. The modelling results suggest that, depending on the parameters involved, hourly and even daily wind and rain input data can provide accurate WDR calculations, while in other situations they can lead to very large errors. Finally, the importance of these parameters is evaluated by conducting WDR calculations with yearly meteorological data records for two cities in different climates.