BS EN 15026:2007

Hygrothermal performance of building components and building elements. Assessment of moisture transfer by numerical simulation. | Status: Superseded, Withdrawn

1 Scope 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.