Cross Ventilation

Dog Legs

A dog leg attenuator is one way to minimise the presence of the attenuator. Experience has shown that it may even be the only feasible method for it to fit into a building’s design. The 90 degree bend also increases the acoustic performance, allowing for an even smaller unit.

Bulkhead

A simple, clean bulkhead containing the Nat Vent Attenuator is the most common way to install and achieve BB93 performance requirements. Its lightweight design allows the MF system to be the supporting structure.

Cross Ventilation Inspiration

Scroll through photos of MACH Acoustic projects featuring cross ventilation and the NAT Vent Attenuator.

Air Flow Performance

The NVA offers extremely low resistance to air flow as it has been designed specifically for low energy buildings.

Acoustic Performance

MACH Acoustics produce calculations based on procedures described in BS EN 10140-1:2010, BS EN 10140-2:2010 and BS EN 10140-5:2010. The NVA is tested using our in house testing rig calibrated to BS 7251.

Noise Atrium Demo

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At one of the London Academies, MACH Acoustics successfully cross ventilated from classrooms into a noisy atrium space, using the NAT Vent Attenuator. This video is to demonstrate the effects of the open vent, compared to closed state.

Cross Talk Demo

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Demo of the cross talk attenuator, installed at HML school with design consultancy from MACH Acoustics.

Cross Ventilator Demo

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A video to roughly guage the NAT Vent Attenuator performance installed within a cross ventilation bulkhead. Cross talk attenuation is audibly noticeable - even on video.

Simple Installation

Installation to a duct typically takes less than 1 hour. The acoustic foam block are simply stacked to create the honeycomb formation in the duct, orientated for air flow through the gaps. Since it isn’t a pre-defined size, there isn’t a tight specification to follow or critical dimensions to build to, it is bespoke without the cost.

Co-ordination

The lightweight and flexible nature allows the product to be installed in a number of unique ways. This can be essential when a large unforeseen obstacle requires to be navigated meaning that traditional metal cased units cannot be manipulated.

MF Track Installation

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A simple Revit render, to illustrate installation within MF Tracking.

Bulkhead Installation

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The simple process for installing the NAT Vent Attenuator into a crosstalk bulkhead. The complete process takes under 1 hour.

Dog Leg Installation

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Focus on Cross Ventilation >

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Core Applications > Dog Legs

Design

A dog leg attenuator is one way to minimise the presence of the attenuator. Experience has shown that it may even be the only feasible method for it to fit into a building’s design. The 90 degree bend also increases the acoustic performance, allowing for an even smaller unit. 

Install

Quick, simple and adaptable Installation is one of the key benefits of the NVA. 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.

 

For a dog leg installation, the NVA is placed between the wall partition, supported by the metal frame. 

Case Study

Ebbw Vale school featues a range of NVA ventilation methods, including a 90deg dog leg style cross ventilation between floors.

 

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Core Applications > Bulkhead

Design

A simple, clean bulkhead containing the Nat Vent Attenuator is the most common way to install and achieve BB93 performance requirements. Its lightweight design allows the MF system to be the supporting structure.

 

Its lightweight design allows the MF system to be the supporting structure but equally, a purpose built bulkhead can be used; plasterboard, timber, metal ducting, etc. Please see the inspiration section for examples of how the NVA bulkhead can be used.

Install

Quick, simple and adaptable Installation is one of the key benefits of the NVA. 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

Regiet Primary School features classroom cross ventilation bulkheads, which not only naturally ventilate the building, but also add to the classrooms' visual design. The design uses a plasterboard duct, with CNC cut alphabet lettering rather than a standard architectural grill. 

 

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Core Applications > Cross Ventilation Inspiration

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Performance > Air Flow Performance

CFD Modelling

Low face velocities (<1m/s) associated with natural ventilation makes accurate measurement of pressure drop difficult and prone to errors. For this reason, MACH Products used CFD to model the pressure drop of the NVA.

25% 1ms
25% 5ms
50% 1ms
50% 5ms
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Performance > Acoustic Performance

Dnew vs Free Area vs Depth

 

The NVA 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

Rogiet Primary School is a timber frame building, located between the M4, M48 and in close proximity to the intercity train between Swansea and London. Such a site is acoustically challenging before even considering natural ventilation. By performing an environmental survey of the site, MACH Acoustics successfully implemented natural ventilation though careful consideration of building placement and well executed cross ventilation - meeting BB93 39Dnew requirement

 

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Performance > Noise Atrium Demo

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Performance > Cross Talk Demo

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Performance > Cross Ventilator Demo

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Installation, Cost and Space Savings > Simple Installation

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Installation, Cost and Space Savings > Co-ordination

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Installation, Cost and Space Savings > MF Track Installation

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Installation, Cost and Space Savings > Bulkhead Installation

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Installation, Cost and Space Savings > Dog Leg Installation

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