2.4 Bench Seating

Adding attenuation to the vented facade of a single storey building is comparatively easier than a multistory building, since it is often possible to extend the building envelope, accommodating the additional depth of the NAT Vent Boxes.

In the case of single storey buildings, it is common to maintain a simple vertical thermal line, by placing the thermal damper into the line of the facade 4. The acoustic attenuation in this instance is placed on the external side of the building. This design approach has been implemented by MACH Acoustics on several projects.

The NAT Vent Box has been installed under bench seating, flower boxes, play boxes, small steps in the facade and other elements. These units have all been used to hide and accommodate the additional facade depth often required when naturally ventilating a building on a particularly noisy site.

A second advantage of single storey buildings is the potential to incorporate the NAT Vent Box above or within roof lines, above corridors, over storage rooms and other areas.

2.5 Window Details

The details used to incorporate the attenuation box into a seat or play box are very similar to those used when incorporating the NAT Vent Box into the facades of buildings. As noted, it is often easier to extend out the facade line of single storey buildings such to accommodate deep attenuators. This in turn means that it is seen as possible to provide natural ventilation irrespective of noise levels. The illustration below 1 was used to control noise break-in to a sensitive office space in close proximity to a major motorway.

Installation of the Attenuator
Forming the NAT Vent Attenuator by tessellated, W-shaped foam blocks, means that this product can easily be dropped into a timber enclosure or metal duct work. The W-shaped tiles compress and can be cut to any size; hence these units are extremely easy to accommodate into the facade of a building 2

2.8 Internal Sliding Doors and Windows

The presented illustrations show alternative arrangements 9 – 13. In this case, the NAT Vent Attenuator is placed on the outside of a thermally insulated door or sliding window. The key advantage of this scheme is that it again eliminates the need for a thermal damper. Additionally, it can often be easier to accommodate the NAT Vent Box outside of the thermal line.

2.10 Secondary Facades - External Ventilation Shafts

An alternative to secondary facades is to use external chimneys. This scheme uses very similar principles to that of a double facade; the difference being that the external chimneys are only used over the ventilation openings. This arrangement clearly has cost and space saving advantages over that of double façades.

A second architectural advantage is that it is possible to provide an animated facade. Forming the chimneys from glass or other translucent materials, allows interesting designs in the form of graphics to be incorporated within the chimneys, adding further interest to the facade of the building.

One of the drawbacks of this design is that acoustic treatment may be required within the chimneys to prevent the spread of sound along its length. This may be required to maintain the acoustic separation across floors. If this is the case, acoustic art work could be used to give the architectural design and also to provide the acoustic absorption within the chimneys.

1.1 Introduction

The NAT Vent Attenuator has been designed to overcome the clashes between natural ventilation and acoustics. The NAT Vent Attenuator allows the fl ow of air into and through a building, whilst preventing the passage of sound. This product can easily be incorporated into the facade of a building, allowing for natural ventilation on all sites, irrespective of environmental noise levels. The NAT Vent Attenuator can also be used to prevent cross talk issues when implementing cross ventilation to atriums/corridors. This product can be made to comply with BREEAM, BCO, HTM, BB93 and other standards. 

The concepts and design specifi cations for this product have come from MACH Acoustics consulting experience. Our experience has shown that current products have a limited acoustic performance, are exceptionally infl exible, costly, and are lacking in technical innovation. Through frustration, knowledge and insight, the NAT Vent Attenuator has been designed and produced by MACH Products. The NAT Vent Attenuator is formed from W shaped tiles manufactured from acoustic foam. These elements are then tessellated and stacked together 11, 12 to form the NAT Vent Attenuator 13. The result is a fl exible product which can be fitted into bulk heads to allow for cross ventilation, or incorporated into the facade of a building to prevent noise break-in. 

The key features of the NAT Vent Attenuator are its patented technology based around the honeycomb structure, its novel W shaped splitter arrangement and the materials from which it is made. A simple manufacturing process delivers a cost effective, lightweight product, which is exceptionally flexible and therefore can be made to fit into a wide range of spaces and locations. The NAT Vent Attenuator is designed and manufactured bespoke for each project and tested using MACH Acoustics in-house test facilities 14 meaning that the acoustic specifi cation of this product meets the exact project requirements.