Air permeability is defined in DIN EN 12207 and is a measure of the amount of air exchange of a closed and locked window element or an external door in relation to a constant air pressure difference. The evaluation is carried out regardless of whether the air exchange takes place via joints between the sash, the frame or the glass rebate. The classification is related to the area of the element or its joint length.
Possible values: 1 to 4
Example: Air permeability 3: The element must meet the requirements of class 3 up to a test pressure difference of 600 Pa.
Tables 2 and 3 of guideline FE-05/2, "Recommendations for the use of windows and exterior doors – Part 1" of ift-Rosenheim provide a clear decision-making aid for the selection of the right air permeability. There, a tabular classification must be made depending on the wind load zone, the installation height and the terrain category. These criteria are also decisive for determining the necessary driving rain tightness.
Important note: The current Energy Saving Ordinance (EnEV) requires at least class 2 for buildings with up to two full storeys and at least class 3 for buildings with more than two full storeys, regardless of the above classification.
Source: bauwion
