Pset_MaterialHygroscopic A set of hygroscopic properties of materials. IfcMaterial IfcMaterial UpperVaporResistanceFactor The vapor permeability relationship of air/material (typically value > 1), measured in high relative humidity (typically in 95/50 % RH). Upper Vapor Resistance Factor LowerVaporResistanceFactor The vapor permeability relationship of air/material (typically value > 1), measured in low relative humidity (typically in 0/50 % RH). Lower Vapor Resistance Factor IsothermalMoistureCapacity Based on water vapor density. Isothermal Moisture Capacity VaporPermeability The rate of water vapor transmission per unit area per unit of vapor pressure differential under test conditions. Vapor Permeability MoistureDiffusivity Moisture diffusivity is a transport property that is frequently used in the hygrothermal analysis of building envelope components. Moisture Diffusivity