Hygrothermal performance of building components and building elements - Assessment of moisture transfer by numerical simulation

This standard specifies the equations to be used in a simulation method for calculating the non steady transfer of heat and moisture through building structures. It also provides a benchmark example intended to be used for validating a simulation method claiming conformity with this standard, together with the allowed tolerances. The equations in this standard take account of the following storage and one-dimensional transport phenomena:  heat storage in dry building materials and absorbed water;  heat transport by moisture-dependent thermal conduction;  latent heat transfer by vapour diffusion;  moisture storage by vapour sorption and capillary forces;  moisture transport by vapour diffusion;  moisture transport by liquid transport (surface diffusion and capillary flow). The equations described in this standard account for the following climatic variables:  internal and external temperature;internal and external humidity;  solar and longwave radiation;  precipitation (normal and driving rain);  wind speed and direction. The hygrothermal equations described in this standard shall not be applied in cases where:  convection takes place through holes and cracks;  two-dimensional effects play an important part (e.g. rising damp, conditions around thermal bridges, effect of gravitational forces);  hydraulic, osmotic, electrophoretic forces are present;  daily mean temperatures in the component exceed 50 °C.