Carbon Dioxide permeability

Amount of carbon dioxide in grams (g) that will diffuse in one day (d) through one square metre of the coating under the action of a defined partial pressure or difference in concentration. It is expressed in g/(M^2.d).

This can be tested using Method A: Gravimetric method or Method B: Carrier gas method

The permeability of membranes towards carbon dioxide is measured as EN 1062 and the method called as Wicke-Kallenback.

Let see some the lab procedure:

 EN 1062 and EN 1504-2 classify the membrane as follows:

Note :

1. CO2 permeabilities of building materials correlated with water vapour permeabilities.•
2. Gas-permeable wall structures lowered the carbon dioxide content of indoor air.•
3. Gas-permeable wall structures did not reduce the need for ventilation.
Hence, 

The more permeable the external wall structures are, the bigger their impact on the CO2 content of indoor air. 

Higher permeability allows more water vapour to pass through the structures, which make them more at-risk for condensation and mould growth. 

Some calculations on the CO2 balance of bedroom air were also made which indicated that the need of ventilation is not reduced by the use of gas permeable structures.
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