Vented Facades
Focus on Vented Facades
One of the main difficulties in designing low energy buildings is the prevention of noise break-in from the different sources affecting modern buildings, including motorways, dual carriageways, trains, aeroplanes and inner city noise.
Getting the acoustic design of the facade right becomes fundamental, so an attenuator in the facade of a building needs to provide high levels of sound resistance within a limited depth .
Core Applications
The Honeycomb Attenuator can be incorporated into the facade of a building to deal with moderately noisy sites, through to sites dominated by noise. It can be tuned to match the frequency characteristics of road traffic noise and other noise sources. This flexibility means it can be installed into a wide range of facades.
Window Vent
The simplest method of enhancing the acoustics of a vented facade is to place the Honeycomb Attenuator behind an open-able window. In this instance, the window is used to control the airflow into the building, maintaining the thermal performance of the facade as well as keeping the weather out.
Bulkhead
A small bulkhead is typically mounted behind the facade opening. The attenuator may simply be supported by MF tracks or may be enclosed by purpose-built ducting (plasterboard, timber etc.). The flexibility of the Honeycomb Attenuator means that actuators to operate the vent/window can easily be accommodated, including service hatches. The window vent can be at low level, high level or incorporated into curtain walling.
Installation
Quick, simple and adaptable installation is one of the key benefits of the Honeycomb Attenuator. The process is broadly the same for most applications. The tessellating foam is arranged into honeycomb pairs by alternating orientation, then simply slid into the duct. Since the foam is malleable and can be cut, fitting it around building services or any on-site alternations necessary can be easily achieved. Installation generally takes under one hour – saving money and construction time.
Case Studies
The London and West London Academies, two large £30m+ academies, are both designed around natural ventilation which incorporates cross ventilation. Both schools were required to meet BB93 and BB101 ‘Ventilation of School Buildings’, so MACH Acoustics worked with Fosters and Partners to develop a practical solution.
The cost of conventional attenuators, along with their size and shortfall in performance, prohibited their use but allowed for the Honeycomb Attenuator.
The academies feature many imaginative implementations of the attenuator as a cross ventilator, all venting into a central atrium. Air passes though the facade via actuated windows and through bulkheads at ceiling height containing the attenuator.
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Design
A vertical louvre is ideal on windowless facades or where window space is at a premium. The facade can either feature a standard weather louvre or a bespoke solution can be designed into the facade face. The vent can be actuated or using a vertical vent, a simple door can be used to control the internal flow of air.
Bulkhead
A small bulkhead is typically mounted behind the facade opening. The Honeycomb Attenuator may be simply supported by MF tracks or may be enclosed by purpose-built ducting (plasterboard, timber etc.). The flexibility of the attenuator means that actuators to operate the vent/window can easily be accommodated, including service hatches. The window vent can be at a low level, high level or incorporated into curtain walling.
Install
One of the key benefits of the Honeycomb Attenuator is its quick, simple and adaptable installation. The process is broadly the same for most applications. The tessellating foam is arranged into a honeycomb formation by alternating orientation, then simply slid into the duct. Since the foam is malleable and can be cut, fitting it around building services or any on-site alternations can be easily achieved. Installation generally takes under one hour – saving money and construction time.
Case Study
Winford Primary School is located directly under the flight path of Bristol Airport, meaning that noise ingress is a significant issue. During the design stage of this building several different options were reviewed. The school is a prime example of the versatility of the Honeycomb Attenuator and MACH Acoustics’ approach. Facade ventilation is incorporated through window and horizontal louvres. Cross ventilation is applied through internal benches and air exhausted through atrium vents. The horizontal louvres feature a 90 degree bend to increase the attenuation of the vent and visual impact.
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Design
A horizontal facade installation is commonly mounted below a window sill. The vent can also be mounted at ground height with an external extruded bulkhead containing the Honeycomb Attenuator, saving internal space and creating a box that can be used for landscaping features – see case study below.
Install
Quick, simple and adaptable installation is one of the key benefits of the Honeycomb Attenuator. The process is broadly the same for most applications. The tessellating foam is arranged into honeycomb pairs by alternating orientation, then simply slid into the duct. Since the foam is malleable and can be cut, fitting around building services or any on-site alternations can be easily achieved. Installation generally takes under one hour – saving money and construction time.
Case Study
Dartington Primary School is located in close proximity to the A384, a large busy road. A number of natural ventilation strategies were developed in cooperation with Arup, including the use of landscaping as a barrier.
This inspiring solid timber project presented challenges internally and externally. Natural ventilation is achieved through an external horizontal bulkhead cross-venting through the roof.
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Design
As forward thinking acoustic consultants, we have done many alternative and discrete facade installations. The Honeycomb Attenuator’s unique flexibility means that it can be installed under bench seating, in flower boxes, play boxes or small steps within the facade.
Install
Quick, simple and adaptable installation is one of the key benefits of the Honeycomb Attenuator. The process is broadly the same for most applications. The tessellating foam is arranged into honeycomb pairs by alternating orientation, then simply slid into the duct. Since the foam is malleable and can be cut, fitting around building services or any on-site alternations can be easily achieved. Installation generally takes under one hour – saving money and construction time.
The bench was constructed with a hollow void to hold the Honeycomb Attenuator. Following the insertion of the attenuator, the final slats were installed across the bench and grill on the inside.
Case Study
St Peter’s Primary School is located in relatively close proximity to the M5 and as such, environmental noise levels are too high to allow for natural ventilation through openable windows. MACH Acoustics was employed by South Gloucestershire Council to provide a range of design options to prevent noise ingress into this classroom. A unique discrete facade vent, contained within a bench seat was employed.
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Facade Inspiration
Performance
As a result of its honeycomb structure and the performance of its acoustic foam, the Honeycomb Attenuator is an exceptionally slimline attenuator with outstanding acoustic performance. It is capable of attenuating exceptionally high levels of noise.
This performance is achieved simply by extending the length of the attenuator (the manufacturing process does not restrict the size of the product). This means the Honeycomb Attenuator can achieve performance levels from 20 dB Dnew to 40+ dB Dnew.
Dnew vs Free Area % vs Depth
The Honeycomb Attenuator frequently performs better on-site. Attenuators are usually tested in accordance to BS EN ISO 10140-1:2010 however this is limited to attenuators with an opening of less than 1m2. Typically on-site an attenuator has an opening in the order of 1.2m2, though this can vary in size for different applications.
Case Study
The outstanding performance of the Honeycomb Attenuator allowed for multiple facade ventilation features at Winford Primary School – located directly below Bristol Airport flight path.
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