2.9 Double Facade

Double facades can be used to control environmental noise break-in without the need for acoustic attenuation. When using a double facade, air enters the building through conventional open windows. The acoustic protection is achieved by acoustically screening these windows by means of a secondary facade. Air enters the void between the two facades via a gap at the bottom of the outer, secondary facade. The edges of the secondary facade are typically taken back to the primary building envelope. Attenuation may be required at the air inlet between the two facades. The advantage of this type of facade is the fact that simple openable windows can be used. It is also possible to form buildings with an interesting and unique appearance.
The drawbacks are clearly cost and space and for these reasons this type of noise control measure is somewhat uncommon.
It is also important to note that the acoustic separation between two rooms can be compromised when windows are open. Acoustic splitters or absorption may be required.