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:
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• heat storage in dry building materials and absorbed water;
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• heat transport by moisture-dependent thermal conduction;
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• latent heat transfer by vapour diffusion;
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• moisture storage by vapour sorption and capillary forces;
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• moisture transport by vapour diffusion;
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• moisture transport by liquid transport (surface diffusion and capillary flow).
The equations described in this standard account for the following climatic variables:
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• internal and external temperature;
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• internal and external humidity;
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• solar and longwave radiation;
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• precipitation (normal and driving rain);
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• wind speed and direction.
The hygrothermal equations described in this standard shall not be applied in cases
where:
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• convection takes place through holes and cracks;
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• two-dimensional effects play an important part (e.g. rising damp, conditions around
thermal bridges, effect of gravitational forces);
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• hydraulic, osmotic, electrophoretic forces are present;
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• daily mean temperatures in the component exceed 50 °C.