Posted by IT MACH

The Future of Windows

29th January 2018Natural Ventilation, Sustainable Acoustics, Window Design

When the Romans invented the glass window, they couldn’t have anticipated the environmental context and settings years later: Windows continue to let in light ages on, however undesirable levels of air and sound also intrude.

MACH Acoustics recognises the importance of noise control through window design. Where simple traditional design limits the use of open windows, we have now developed a range of unique software tools to help overcome noise break-in in residential buildings, offices and schools to prove that open windows can be used in noisier environments than previously thought.

Working with your design, we will improve the acoustic performance of open windows and provide the solution that will work best for your project. It could be as simple as an extended window frame, proven to reduce sound; external baffles; or changing the shape of the window itself.

Download our book for free from iTunes to read how our ground-breaking, software tools can show you the future of windows, and check out the video clip also below.

https://itunes.apple.com/us/author/mach-acoustics/id1041471077?mt=11
https://www.youtube.com/watch?v=0IzL8MpbtOs&feature=youtu.be#

Posted by IT MACH

Keep passing the Open Windows

29th January 2018Natural Ventilation, Window Design

Introduction

This Blog Post is taken from the latest MACH Acoustics book “The Acoustics of Open Windows” – Chapter “The Future of Windows”. This book can be downloaded as an iBook from: https://itunes.apple.com/gb/book/the-acoustics-of-open-windows/id1049860606?mt=13

This book publishes part of Ze Nunes’ ongoing PHD, on the subject of visualizing sound and air in low carbon buildings.

At MACH we see that natural ventilation is one of the strategies of choice for forward thinking clients interested in low-energy buildings. However environmental noise break-in can be an issue, resulting in clumsy acoustic attenuators or windows being kept shut.

MACH Acoustics recognizes the benefits of noise control through window design. The team at MACH has therefore developed unique modeling tools, assessing noise mitigation solutions based around improving the acoustic performance of open windows, such to overcome noise break-in issues to residential buildings, offices and schools.

Extended Window Frame

One of the key factors affecting the sound reduction of an open window, is its ability to screen sound, i.e. the harder it is to see the sound source through the opening of the window, the better its acoustic performance. Hence by simply extending the frame of the window, as shown, the sound reduction of a simple window can be enhanced. The next two slides illustrate this effect, with an interactive model showing the effects of extending the frame and a video providing a subjective illustration of this change.

Baffled Facades – Illustrations

An alternative way of enhancing the performance of an open window it is place a baffle over its opening. MACH Acoustics’ analytical tools and measurements facility can be used to determine the size and position of the baffle such to provide the required acoustic performance from an open window.

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Bath University PhD helps us see what we hear

29th January 2018Acoustic Design, Natural Ventilation

MACH’s very own Ze Nunes is embarking upon a PhD at Bath University, and the research he will do should not only change the way acoustics is heard but also viewed.

Entitled, “A common Multi-disciplinary visualization of sound and air in low carbon building realizes modern building design intent fully”.

He justifies that the lack of design solution and basic conceptual understanding of acoustics is often the reason for not taking a low carbon building design strategy forwards – the primary aim of this work seeks to ensure that all stakeholders in the design process are equipped with the necessary knowledge to engage them fully in the design, enabling them to delivering better buildings as a result of reduced conflicts. A shift in the appreciation of acoustics in low carbon buildings is required – this will make acoustics an incorporated aspect of the design process, and not merely a stand-alone remedial discipline.

The invisible link between acoustic and natural ventilation paths in buildings results in conflicts between other disciplines, limiting the full environmental potential of a building to be realized.This lack of understanding can be breached by using inspirational collaborative methods to inspire key stakeholder engagement. Modeling techniques, interpretation of data, seeking symmetry of physics in the properties of a building will all assist in presenting the building in a more visual way. The principle behind this concept being, “if you can see the acoustics we can fully understand the acoustics”.

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Case Study: Llwynderw Primary School

12th March 2014BB93, Case Study, Cross Ventilation, Exhaust Stacks, NAT Vent Attenuator, Natural Ventilation, Sustainable Acoustics, 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 square chimney, which vented out through natural vent towers on the roof of the building.

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:

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Cross Ventilating into a Noisy Atrium with NAT Vent Attenuator

5th March 2014Atrium, NAT Vent Attenuator, Natural Ventilation, Video

The video above aims to demonstrate the performance of the NAT Vent Attenuator, and its ability to naturally ventilate, even between noisey areas. For more information about using central atriums, have a look at our previous post on atriums and case studies: Archway Primary School and Winford Primary School

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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.

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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.

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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:

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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?

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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.

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.

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)

Introduction

Extended Window Frame

Baffled Facades – Illustrations

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