CEN/TC 89/WG 10 - Moisture

This document specifies the model components to be used in a numerical hygrothermal simulation model for calculating the transient transfer of heat and moisture through building structures.
This document specifies a method to be used for validating a numeric hygrothermal simulation model claiming conformity with this document.

MINOR REVISION

ISO 12572:2016 specifies a method based on cup tests for determining the water vapour permeance of building products and the water vapour permeability of building materials under isothermal conditions. Different sets of test conditions are specified.
The general principles are applicable to all hygroscopic and non-hygroscopic building materials and products, including insulation materials and including those with facings and integral skins. Annexes give details of test methods suitable for different material types.
The results obtained by this method are suitable for design purposes, production control and for inclusion in product specifications.

2012-12-06 GVN: Draft for // vote available at ISO/CS (see notification in dataservice on 2012-12-04)

ISO 13788:2012 gives simplified calculation methods for:
      The internal surface temperature of a building component or building element below which mould growth is likely, given the internal temperature and relative humidity. The method can also be used to assess the risk of other internal surface condensation problems.
      The assessment of the risk of interstitial condensation due to water vapour diffusion. The method used does not take account of a number of important physical phenomena including the variation of material properties with moisture content; capillary suction and liquid moisture transfer within materials; air movement from within the building into the component through gaps or within air spaces; the hygroscopic moisture capacity of materials.
      The time taken for water, from any source, in a layer between two high vapour resistance layers to dry out and the risk of interstitial condensation occurring elsewhere in the component during the drying process.

This Technical Report describes a method of test for determining the resistance of pitched roof coverings to wind-driven and deluge rain.
The test method is applicable to discontinuously laid unsealed small roof covering elements such as clay tiles, concrete tiles, slates, fibre cement slates and stones.
NOTE   The test method may be adapted for fittings.

This standard specifies a procedure for determining the hygric expansion or contraction behaviour of building materials as a function of moisture content. It isapplicable for mineral, porous hygroscopic materials. For other materials showing moisture-induced deformations, the procedure described can be adapted in a suitable way taking into account their specific moisture behaviour. This standard is relevant to material states when reversible expansion/contraction processes, may be assumed, but not states governed by irreversible process such as shrinkage after material production or after initial drying.

This standard specifies a method for determining, by partial immersion with no temperature gradient, the short-term liquid water absorption coefficient. It is intended to assess the rate of absorption of water, by capillary action from continuous or driving rain during on site storage or construction, by insulating and other materials, which are normally protected. The method is suitable for renders or coatings tested in conjunction with the substrate on which they are normally mounted.
It is not intended to assess the absorption of water by materials used under water or in overall contact with saturated ground, where a total immersion test is more appropriate.

This standard specifies a general method for assessing the driving rain resistance of wall systems through determining the water tightness of wall systems under pulsating air pressure.

This standard, which is applicable to porous water permeable materials, specifies a general method for determining the free water content of building materials by drying at elevated temperature. The standard does not specify the method for sampling.

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.

This standard specifies a method based on cup tests for determining the water vapour permeance of building products and the water vapour permeability of building materials under isothermal conditions.  Different sets of test conditions are specified.
The general principles are applicable to all hygroscopic and non hygroscopic building materials and products, including those with facings and integral skins.  Annexes give details of test methods suitable for different material types.  This standard is not applicable in the case of test specimens with water vapour diffusion-equivalent air layer thickness values less than 0,1 m, as a result of increasing uncertainty in the measurement results.  If the measured water vapour diffusion-equivalent air layer thickness is greater than 1500 m the material can be considered impermeable.
The results obtained by this method are suitable for design purposes, production control and for inclusion in product specifications.

This standard specifies a method to calculate the density of water vapour flow rate for cold pipes,  and the total amount of water absorption over time. This calculation method applies only when the water vapour partial pressure difference is perpendicular to the axis of the pipes and the water vapour partial pressure is constant at all points equidistant from the axis of the pipe.

This Standard specifies two alternative methods for determining hygroscopic sorption properties of porous building materials and products: a) using desiccators and weighing cups (desiccator method); b) using a climatic chamber (climatic chamber method). The desiccator method is the reference method. The standard does not specify the method for sampling.

This standard gives calculation methods for:
a)   The internal surface temperature of a building component or building element below which mould growth is likely, given the internal temperature and relative humidity - the method can also be used to assess the risk of other surface condensation problems.
b) The assessment of the risk of interstitial condensation due to water vapour diffusion. The method used assumes built-in water has dried out and does not take account of a number of important physical phenomena including:
- the dependence of thermal conductivity on moisture content;
- the release and absorption of latent heat;
- the variation of material properties with moisture content;
- capillary suction and liquid moisture transfer within materials;
- air movement through cracks or within air spaces;
- the hygroscopic moisture capacity of materials.
Consequently the method is applicable only to structures where these effects are negligible.