(UNI EN 1026 - UNI EN 12207)
The characteristic of a closed window to let air filter inside when there is a difference in pressure between its inner and outer surfaces. According to the test method, the window must be secured to the test wall: test equipment then causes a pressure difference between the window’s inner and outer surfaces, thus enabling the measurement of volume of air dispersed. Determination of the frame’s air permeability is based on the volume of dispersed air, total area of the window, and length of extendable joints.
Classification is determined by regulation UNI EN 12207, which includes 4 classes of performance (1, 2, 3, 4). The highest classification of performance against air infiltration is class 4.
Doc Legno windows (Item 56, Item 68, Item 92) belong to class 4.