Empirical Investigation of the Hygrothermal Diffusion Properties of Permeable Building Membranes Subjected to Variable Relative Humidity Condition

Hygrothermal modelling is increasingly used to inform building envelope design. A key input for these calculations the material’s vapour diffusion properties. Respecting a growing international concern, this research has questioned appropriateness of current test method establish construction material This article reports on empirical measurement properties two vapour-permeable membranes commonly in Australia residential systems when subjected variable relative humidity conditions. The involved completing dry cup and wet standard tests as specified ISO 12572, (23 °C 50% RH). Further were then conducted temperature remained at 23 but changed 35%, 65% 80%, respectively, order know if are same or change with varying humidity. results from under different conditions non-linear different. These indicate behave differently exposed In conclusion, demonstrates that resistivity inadequate, hence need more detailed ranges represent experienced within building’s external envelope.