This standard defines the practical application of hygrothermal simulation software used to predict one-dimensional transient heat, air and moisture transfer in multi-layer building envelope components subjected to non steady climate conditions on either side. The following examples of transient, one-dimensional heat and moisture phenomena in building components can be simulated by the models covered by this standard: - drying of initial construction moisture; - moisture accumulation by interstitial condensation due to diffusion and convection in winter; - moisture penetration due to driving rain exposure; - summer condensation due to migration of moisture from outside to inside; - exterior surface condensation due to cooling by long wave radiation exchange; - moisture-related heat losses by transmission and moisture evaporation.