Field study on the air change rate behind residential rainscreen cladding systems: A parameter analysis

Publication date: January 2016
Source:Building and Environment, Volume 95
Author(s): Jelle Langmans, Tadiwos Z. Desta, Lieven Alderweireldt, Staf Roels
The article at hand presents the results of an extensive field study in which the air change rate behind rainscreen claddings has been measured. In total eight different full-scale test walls have been tested. The main parameter variations are: 1) the cladding system (brick veneer and sidings), 2) orientation (South-West and North-East) and 3) area of ventilation openings. To increase the reliablity of the results four measuring techniques to determine the air change rate have been applied. The accuray and applicability of these methods have been discussed in a previous paper. The current article focusses on the impact of the three abovementioned parameter variations on the overall air change rate. Moreover their effect on the hygrothermal conditions in the cavities will be outlined. The results show that the cavity ventilation for brick veneer (1–10 ACH) is two order of magnitude lower than behind sidings (100–1000 ACH). This difference also reflects on the drying potential of both systems. The vapour content behind the sidings follows closely the outer climate. In contrast the vapour pressure behind brick veneer can be significantly higher than the outer climate which is induced by its moisture buffer capacity and its low ventilation rate.