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Case Study: Hertfordshire University

26th February 2014Architecture, BB93, BREEAM, Case Study, NAT Vent Attenuator, Under Floor, Vented Facades

The Law Court at the University of Hertfordshire is a £10M advanced facility, including a full-scale courtroom with public gallery, a working law clinic, a purpose built mediation centre and a dedicated CPD suite, as well as a large number of offices and classrooms. A BREEAM project, the building was to be naturally ventilated. MEP designers AECOM specified the Mach Acoustics NatVent Attenuator to provide a vented facade solution using weather louvres, connected to a raised, vented floor containing the Nat Vent Attenuator.

Installing the NVA under-floor is a veryeffective method when dealing with high noise levels. The vent openings are made within the spandrel panel between transoms. Air passes into the cellular space by passing through a external vent opening, through the NAT Vent Attenuator. The floor void is used as plenum – air enters the rooms above by means of floor diffusers.

Image provided by Aecom

Situated on a busy campus and next to a busy bus route, the natural ventilation strategy needed to be acoustically attenuated. Adding to the challenge was the fact that the building had already be designed for air inflow through the flooring, with acoustic dampers, louvre and bird mesh limiting flow to an already small 1.5m2 face area. Only thanks to the adaptable NVA foam, MACH Products was able to design the attenuator around modulated Kingspan flooring, sitting on pedestals 360mm high, fully filling the void. The profile was designed to the same size as the 600x600mm grid created by the flooring, such that the NVA would be easy to install. By installing in segments like this, we were able to create the required length of attenuator for the noise level at the facade.

Due to the bespoke nature of the NVA, the attenuator could be simply installed in coordination with the modular grid based flooring. The NVA segments were slid into place between the pedestals (1/4 circle sections were added to the corner profile to account for the structure), followed by the matching 600x600mm floor sections. Building services often exist within the flooring void, including a heated element in this case. The NVA foam can be easily adapted on site to accommodate for these items, unlike a common pre-defined attenuators.

Click the preview below to download the full case study:

Posted by IT MACH

Case Study: Dartington Primary School Nat Vent Box

19th February 2014BB93, Case Study, NAT Vent Attenuator, Natural Ventilation, Open Plan Teaching, Vented Facades

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 bulkhead cross-venting through the roof.

The first step of any noise break-in assessment is to establish levels across the site. This was done by carrying out noise monitoring throughout the site, over the full operational hours of the school.

A noise map was then created and used to assess the required level of attenuation required by facades of the school. The results indicated that the noise levels at the facades to the classroom block were higher than desirable.

The solution to the high noise levels at the building facade was to naturally ventilate using an external ground floor bulkhead containing the NVA, with hot air flowing out through openable window vents also containing the NVA. This solution allows for natural ventilation when it would otherwise not be possible through an open window for example. In addition to this, an acoustic screen and a strategically placed earth bund were designed to reduce noise levels at the classroom facade. The bund was formed from recycled tires, adding to the sustainability credentials of the building. Dartington Primary School is an inspiring development because a solid timber construction system has been used. BB93 also sets room reverberation requirements and the exposed timber in combination with barn shaped classrooms required some form of room acoustic treatments. The solution used was several acoustic beams provided by MACH Products (below).

The school met all BB93 requirements and BB101 ventilation specifications. Not only this but the finished design was pleasing and added function to the facade besides ventilation. The build was featured in ‘BD Reviews’ sustainability issue, a bow to the innovative design by MACH Acoustics, White Design and Arup. The photo below features the wooden beams put in place to reduce the reverberation. Click the preview below to download the full case study.

Posted by IT MACH

Demonstration of Sound Level Difference through Window Opening

6th February 2014Eco Buildings, Natural Ventilation, Research, Room Acoustics, Vented Facades, Ventilation Systems

When testing the performance of the NAT Vent Attenuator at Winford Primary School, we performed a noise break in assessment whilst opening a window. The video above illustrates the sound level difference has a steep decay from a small opening.

Posted by IT MACH

Case Study: Ebbw Vale Learning Zone

5th December 2013BB93, Case Study, Cross Ventilation, NAT Vent Attenuator, Natural Ventilation

The Learning Zone lies at the heart of the regeneration and redevelopment of the former steelworks at Ebbw Vale, the largest regeneration project in Wales. MACH Acoustics worked with Architects BDP to develop a natural ventilation strategy between classrooms.

MF tracks were used to hold the NVA – creating a cost effective bulkhead, with acoustic attenuation and building services able to coexist in the same space.

The case study is a prime example of the NVA’s ease of install and space saving advantages. The render above demonstrates how the NVA installs onto the MF tracking system.Generally a 1100mm depth NVA is used to sit between the standard 1200mm width between MF supports. The foam is positioned within the MF track in layers to form the honeycomb arrangement, which allows air to flow whilst attenuating noise.

Click the preview below to download the full case study:

Posted by IT MACH

Finite-Difference Time-Domain Models of Open Windows

18th November 2013KTP, Natural Ventilation, Research, Sustainable Acoustics, Vented Facades

An important area of research for MACH Acoustics, below are a few examples of a FDTD model we have produced to demonstrate various open window conditions.

First a top swung window, notice the noise ingress into the room.

The above but as a bottom swing.

An open window representation.

The above but with a internal baffle.

If you find this content interesting, why not arrange a CPD with MACH Acoustics?

Posted by IT MACH

Case Study – University of Hertfordshire Law Court

11th October 2013Architecture, BB101, BB93, NAT Vent Attenuator, Natural Ventilation, Under Floor, Vented Facades

The Law Court at the University of Hertfordshire is a £10M building with advanced facilities, including a full-scale courtroom with public gallery, a working law clinic, a purpose built mediation centre and a dedicated CPD suite, as well as a large number of offices and classrooms. Aiming for BREEAM status, the building was to be naturally ventilated. MACH Acoustics provided a vented facade solution using weather louvres, connected to a raised, vented floor containing the NVA.

Situated on a busy campus and next to a busy bus route, the natural ventilation strategy need to be acoustically attenuated. Adding to the challenge was the fact that the building had already be designed for air inflow through the flooring, with acoustic dampers, louvre and bird mesh limiting flow to an already small 1.5m2 face area.

Only thanks to the adaptable NVA foam, MACH was able to design the attenuator around modulated Kingspan flooring, sitting on pedestals 360mm high, fully filling the void. The profile was designed to the same size as the 600x600mm grid created by the flooring, such that the NVA would be easy to install. By installing in segments like this, we were able to create the required length of attenuator for the noise level at the facade.

The vent openings are made within the spandrel panel between transoms. Air passes into the cellular space by passing through a external vent opening, through the NAT Vent Attenuator. The floor void is used as plenum – air enters the rooms above by means of floor diffusers.

Building services often exist within the flooring void, including a heated element in this case. The NVA foam can be easily adapted on site to accommodate for these items, unlike a common pre-defined attenuators.

The build meet the BB93 and BB101 requirements as a teaching space whilst creating a dynamic and pleasant space for students. MACH Acoustics and it’s partners helped the centre become one of the most innovative law schools in the UK and was recently awarded ‘The Most Sustainable Construction Award 2011’ by Building Futures and has been short listed for several other awards.

Click the preview below to download the complete case study (pdf)

Posted by IT MACH

Case Study – Llwynderw Primary School

4th October 2013Architecture, BB93, BREEAM, Cross Ventilation, NAT Vent Attenuator, Natural Ventilation, Vented Facades

Llwynderw Primary School is a project in Abergaveny that MACH Acoustics worked on in partnership with Stride Treglown Architects and Willmott Dixon

The school incorporates natural ventilation through a vented facade and openable windows, which cross ventilate classrooms via a central chimney – saving money, building space and simplifying the construction.

An important stage in the acoustic design of a building is an environmental noise survey of the existing site, a service provided by MACH Acoustics.

Using the data collected, a dynamic noise map was constructed and used to access the noise levels at each facade and the resulting noise break-in within the teaching spaces. It was clear that the site was not particularly noisy and that an open window would provide enough attenuation at the facade facing away from the roads – simple and low cost.

A ventilation strategy was developed in close coordination with Stride Treglown Architects – using the sound map – which efficiently attenuated noise on each facade.

On the noisy road facing facades, a cedar shingles feature created a duct, with intake perpendicular to the ground and containing the NVA. A 90deg arrangement like this increases attenuation and minimises impact on building space – highlighting the bespoke design options that the NVA offers. The quieter rooms with central chimney simply used openable acoustic windows.

The central chimney shown above is the highlight of the natural ventilation project. Each stack of classrooms featured a small sqaure chimney, which vented out through natural vent towers on the roof of the building. Details of the this are shown on the right.

A testament to the NVAs versatility whilst maintaining class leading acoustic performance, the build was impressive architecturally whilst naturally ventilating and meeting both BB93 and BB101 requirements as a teaching space.

Thanks to a partnership between MACH Acoustics and Strides, the building received a BREEAM ‘Very Good’ rating and was well received by parents, pupils and residents of the area.

Click the preview below to download the full case study (pdf)

Posted by IT MACH

The NAT Vent Attenuator

28th April 2011NAT Vent Attenuator, Resources

The Natural Vent Attenuator (NAT Vent) is a product specifically designed for low energy buildings which overcomes the problem between natural ventilation and acoustics. The NAT Vent can be incorporated into corridor walls to provide cross ventilation to an atrium, installed within ventilation stacks such to service multiple floors through a single stack or incorporated into the façade of a building to mitigate noise ingress from the surrounding environment.

The key advantage of the NAT Vent Attenuator is its exceptional acoustics performance; this performance has been achieved through extensive research and testing and by designing the product specifically around natural ventilation. The NAT Vent meets Building Bulletin 93 – ‘Acoustics Design for Schools’ requirement for cross ventilation and allows for naturally vented facades even on the noisiest of sites.

Click the preview below to download our brochure and learn more.

Posted by IT MACH

Cross Ventilation – Atriums

28th April 2011Cross Ventilation, NAT Vent Attenuator

Low energy buildings works most effectively when “cross ventilation” is employed. In this case, air is brought in through the building façade and then passes across a given space and out through a partition into another part of the building e.g. corridor, atrium, etc. In the case of cross ventilation, the spread of noise through a partition containing vents can be a major limiting factor. The Nat Vent is therefore used to maintain the acoustics performance of a partition.

The core advantage of the NAT Vent Attenuator is the fact that it can be made to comply with the BB93 and other regulations, and is sufficiently flexible to be installed into a range of spaces

For further information please see Chapter 3. Acoustic and cross ventilation ‘Sustainable Acoustics’, Pages 24 to 27
.

The link below take you to a series of case studies where the NVA has been use to allow for natural ventilation on a noise site:

Winford Primary School
Rogeit Primary School

Retrofit into existing University Building – Bristol Uni Educational Building
West London Academies

Posted by IT MACH

Case Study – St Peter’s Primary School Discrete Facade

28th April 2011BB93, Case Study, Discrete, NAT Vent Attenuator, Vented Facades

St Peters 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.

One of the unique elements of this project was a considerable slope across the site. The solution was to pile the site and use suspended slabs to form the classrooms. To provide an external play/learning area to each of the classrooms, a suspended timber deck was employed. The solution here was to accommodate the attenuator within bench seating. Air was brought in from under the timber decking and then cross vented across the classroom before being released at high levels on the quiet side of the building.

Click the preview below to download the complete case study.

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