Accuracy of semi-empirical models for wind-driven rain using different data processing methods for wind velocity and direction

Abstract

Determining the distribution pattern of wind-driven rain (WDR) on a building facade can provide crucial boundary conditions for analyzing its heat and moisture transfer, and this is often performed using semi-empirical models. However, the accuracy of semi-empirical models remains questionable, particularly with uncertain input data. In this study, high-resolution field measurements were performed on a pilot building to verify the accuracy of the ISO and ASHRAE semi-empirical models under different data processing methods for wind velocity and direction. The results indicate that the WDR catch ratios calculated using the ASHRAE model are always larger than those of the ISO model with the same input wind velocity and direction. Combining the wind velocity and direction from the probability statistics with the ASHRAE model produces the most accurate results, with predictions ranging from 101%–279% of the measured values. Wind velocity and direction averages based on vector averages are unsuitable for semi-empirical models.