2.7 Louvred Facade

As shown, the NAT Vent Box can be used to provide a vertical air inlet. This arrangement provides a design opportunity to provide colour and depth to a building’s façade.

A second advantage is that it is often possible to place NAT Vent Boxes within the corner of a room. Here, it may be easier to incorporate a deeper Vent Box 1 - 4. Alternatively, it may be possible to pull the facades out in certain areas such to accommodate a deeper NAT Vent Box. Both of these designs are recommended when external noise levels are particularly high.

A further benefit of using a vertical louvre is the potential to incorporate acoustic attenuation into the blades. For free area reasons, this design can only be adopted if the louvres run vertically.

2.11 External Spaces as Secondary Facades

Secondary Façade as a Functional Space
Often there is a need for spaces such as cloakrooms, changing areas, walkways, balconies and other non-acoustically sensitive spaces to be located adjacent to a building. By making these spaces external and unheated, i.e. open covered spaces, it is possible to use these areas as a secondary facade . If required, additional acoustic protection can be added by means of placing an attenuator within the secondary facade 1. This attenuator could be located under benches, cupboards, shelving areas, raised areas etc. This would be an ideal way of preventing noise break-in from low flying aircraft, nearby rail lines, or a large main road such as a motorway.

Acoustic screening and ventilating from under a building
Acoustic screening is an effective method of controlling noise break-in to a building.
Illustration 2 shows how a large, suspended, raised (play) area was used to accommodate the fall in the land across a school site. This play area provided a highly effective screen to aircraft noise and potentially other major noise sources. The acoustic attenuation is provided as the vents under the deck have little or no visibility to the noise sources affecting the development. In simple terms, providing an air inlet under the building prevented noise ingress into the building.