Driving Rain on Building Envelopes— II. Representative Experimental Data for Driving Rain Estimation

A practical numerical method for driving rain estimation was presented in “Driving Rain on Building Envelopes—I” (Blocken and Carmeliet, 2000). An important prerequisite in employing this method is that the climatic data used as input are representative. In this paper, the attainment of representative experimental data for driving rain estimation is analysed. The importance of a sufficiently small time step to obtain representative climatic data measurements is indicated. It is shown that representative averaged values for wind speed and rainfall intensity for longer time steps can be obtained by averaging the measured data with the rainfall amounts as weighting factors. The effects of using different averaging techniques on the accuracy of the calculated driving rain results are investigated. It is found that the presented weighted averaging technique can provide accurate representative averaged data, whereas commonly used averaging techniques can give rise to large errors.