Methods for the quantification of driving rain on buildings

Driving rain is one of the most important moisture sources affecting the performance of building envelopes. Knowledge of the quantity of driving rain impinging on building facades is essential in order to design buildings with a satisfactory hygrothermal performance. The intent of this paper is to provide the reader with a view on existing methods for quantifying driving rain. Three categories are distinguished: experimental methods, empirical methods, and numerical methods. The principles of each method are described, the state-of-the-art is outlined, and the use is illustrated by application to the lowrise VLIET test building of the Laboratory of Building Physics, KULeuven. It is shown that the complexity of driving rain requires methods to balance labor and computational expense against accuracy and completeness.