The regulation is : UNI EN 12207.

Air permeability is divided into four classes from 1 to 4 (the highest).
The test is made in order to verify the presence of air infiltration, when there is a different pressure between inside and outside of window.


In the environment doesn’t enter draughts, even if wind could blow very fast.
However, you avoid heat dispersion during winter and cold during summer.

Other advantages are, for example, dust’s reduction in rooms, windowsills, while blinds remain clean for more time. It is obstructed from smog and other smells.

Less dust, energy conservation, economic conservation - I Nobili
Air permeability performance - I Nobili