EVS-EN 15026:2007

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.