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Posted by IT MACH

Residential Developments – Example Report

16th September 2010Acoustic Flanking

MACH Acoustics have recently been asked to demonstrate the quality of our work and the approach taken to residential building design. As a result we have loaded several example residential reports to the MACH Library.

Residential Developments - Example Report

Click on image to download example report

This report covers the acoustic design review for City View in Bristol, where acoustic consultancy was provided for a £7.5m residential development. Along with acoustic consultancy, pre-completion testing was carried out. As a result of our clearly illustrated work, the design team, quantity surveyor and the site team understood the acoustic requirements of this building. This resulted in a full compliant building in line with Approved Document E. Early sound tests was use to demonstrate that the cost effective, lean design work. These sound tests also proved to be exceptionally useful in helping the construction team to understand importance of key details.

The second part of this document is a detailed architectural review covering acoustic flanking of the residential block within the St Austell Town Centre Redevelopment project. This was a £70m development consisting of car parks, residential buildings, a cinema block and a shopping mall. MACH Acoustics provided acoustic consultancy, pre-completion testing, early sound testing, PPG24 assessments and BS4142 assessments. Detailed PPG24 and BS4142 assessments were required for planning reasons.

Posted by IT MACH

Creative forms of Room Acoustic Treatment in Teachings Spaces

9th September 2010Uncategorised

BB93 ’Acoustic Design for schools’ provides a range of target reverberation times for teaching spaces. These reverberation times are aimed at ensuring acceptable speech intelligibility levels, as well as reducing excessive levels of noise increase within teaching spaces.

Dartington Primary School is an inspiring development because a solid timber construction system has been used. Exposed timber in combination with barn shaped classrooms offered the potential to add interesting forms of room acoustic treatments. The solution used was several acoustic beams provided by MACH Products.

Acoustic beams are a highly effective way of absorbing sound within a room and have the additional benefit of being complementary to the architectural design of a space. Acoustics beams are more effective that flat products since absorption is offered by both sides of the beam.

To assess the required levels of room acoustic treatment, a sophisticated acoustic model was built which allowed the amount of treatment required in each teaching space to be accurately predicted. The Ray tracing model enabled the dimensions of each beam (principally its height) to be adjusted, such to meet BB93 requirements.

As in the case of all MACH Acoustics consultancy, a full design review of room acoustic treatments was presented. Our acoustic consultancy resulted in a design report, providing a wide range of design options and ideas. This report can be downloaded here.

Posted by IT MACH

MACH Acoustics CPD Sessions

8th September 2010CPDs, Integrated Designs, Low Energy

Knowledge, creativity and integrated designs are seen to be the three main factors in achieving low energy, functional and beautiful buildings. Integrated design requires the design team to have a good understanding of each other disciplines. To share some of MACH Acoustics knowledge and to encourage integrated designs, MACH Acoustics offer a range of Acoustic CPD (Continual Professional Development) sessions.

MACH Acoustics CPD’s are based around 20min modules and it is therefore possible to combine modules such to best suit your CPD requirements. The modules below have been arranged into clusters, which indicate MACH Acoustics’ recommended combinations.

NATURAL VENTILATION AND OPEN PLAN TEACHING
Vented Facades (20 min) This module demonstrates a range of schemes to achieve natural ventilation on noisy sites. The orientation of the building is addressed by means of videos and other visuals. A case study is provided for a naturally ventilated primary school sandwiched between the M4, M48 and an intercity train line. Four further case studies are also presented.

Cross Ventilation (20 min) A wide range of design principles are reviewed in the form of eight case studies. These case studies cover both the use of ventilation chimneys and cross ventilation to circulation spaces/atriums. The presentation also looks at Alternative Performance Standards to BB93 cross vent requirements, based upon MACH Acoustics paper presented at the Institute of Acoustics Conference.

Open Plan Teaching Spaces (20 min) The design concepts used to deliver two highly successful and creative open plan teaching spaces, accommodating 60 to 90 pupils is presented. The presentation includes the effects of room layouts, acoustic treatments, acoustic screens, the use of audio visual solutions, as well as a range of design tools such to comply with BB93 ‘Acoustics Design for Schools’.

Alternatively, Room Acoustics and Office Acoustics (20 min) can be presented rather than Open Plan Teaching Spaces (20 min)

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MACH OVERVIEW OF SUSTAINABILITY AND ACOUSTICS

Sustainability and Acoustics (60min) – This CPD is based upon MACH Acoustics book ‘Sustainable Acoustics’. This CPD provides an insight into the effects of acoustics on low carbon buildings. The CPD starts with noise mitigation methods used in combination with vented facades. Noise maps and other details are all discussed in length within this section. Cross ventilation is seen to be an effective form of venting large spaces. The acoustic implication of chimneys and cross talk attenuators are therefore reviewed. Sound insulation can impact on the sustainability of a building hence timber structures and performance standards, along with auralization (audio simulation of spaces before they are built) is presented. Finally, the use of sustainable recycled products and room acoustic treatments is reviewed.

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ACOUSTICS, SITE DETAILS AND ROOM ACOUSTICS

Acoustics (20 min) This module covers the basic principles of acoustics. dB, doubling of sound level, background noise, the sound insulation of block and stud walls, flanking details, structure borne noise and room acoustics are all covered. Explanations are kept simple and a wide range of videos, audio demos and example details are used to explain acoustics. Due to its simplicity, this is one of our most popular modules.

Construction Details (20 min) MACH Acoustics Acoustics module is applied to drawings and details. This process is aimed at ensuring that designers do not make mistakes. The second half of this module presents a wide range of photographs taken across many sites. Key construction details are presented, from block work details, to service penetrations, hence this is a good site based CPD.

Room Acoustics and Office Acoustics (20 min) Soft treatments are important to provide a comfortable, functional environment in which to work, teach and relax in. The importance of soft treatments and alternatives to the uninspiring acoustic ceiling tiles are therefore the basis of this module. The performance of creative forms of room acoustic treatments is presented along with indicative quantities of treatment for different spaces.

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ROOM ACOUSTICS

Room Acoustics and Office Acoustics Extended (40 min) This module is an extended version of Room Acoustics and Office Acoustics in which additional case studies are presented. This module presents auralization and the benefits of this tool. Highly creative room acoustic treatments are also presented through case studies which include the Foreign Commonwealth Office – a listed building with exceptional acoustic challenges; an open plan Spa requiring high levels of privacy between treatment areas and the design of acoustic interactive spaces within The Eden Projects educational building. This module is seen to be a highly creative, architectural, concept led CPD and works well as a short presentation on its own, or combined with another 20min module.

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OTHER SUBJECTS

In addition to the above modules, MACH Acoustics also have the following modules and we are more than happy to combine these with any of the modules listed above. We are also happy to create new material covering most subjects.

P20 – Part E (Building Regulations regarding Residential Dwellings) (20 min)

P60 – Student Accommodation (20 min)

P80 – Value Engineering (20 min)

If you require a CPD to be taken forwards, please feel free to contact Ze Nunes at MACH Acoustics by email (ze@machacoustics.com) or by phone on 07730 590904.

Posted by IT MACH

MACH Acoustics is expanding

7th September 2010Acoustic Testing

MACH Acoustics has recently taken on three new members of staff. This growth has broadened the range of skills and experience within the company and we are now is strong position to expand our services in environmental acoustics. The new team members have brought with them experience in the following areas of environmental acoustics:

   •   Wind farm acoustic assessment
   •   Road and rail noise assessment
   •   Industrial noise assessment

WINDFARMS AND URBAN TURBINES

New staff at MACH Acoustics have experience in all aspects of wind farm developments from feasibility and planning through to compliance testing.

Background noise surveys
Background noise surveys are carried out using weatherproof environmental noise loggers. Noise loggers are placed at key residential locations to establish the base line noise levels. The measurement data is they correlated with wind speed measurements to establish the relationship between wind speed and background noise level. The

Noise assessment
Using computer modelling software (CADNA), wind turbine noise can be predicted at nearby residential locations over a range of wind speeds. The predictions are then compared with theETSU-97 noise limits.
Modelling software is also used in the turbine selection process and to fine tune site layouts and mirco-siting

Sound power level testing
MACH Acoustics can perform sound power testing according to the methodology of International Standard IEC61400-11 Wind turbine generator systems – Part 11: Acoustic noise measurement techniques (IEC61400-11) to verify that the measured sound power levels comply with the sound power levels guaranteed by the manufacturer.

Compliance assessments
Post construction noise assessment is conducted using noise loggers and wind speed data. Regression analysis is used to establish the post-construction background noise level at each monitoring location.
These values are able to be compared with pre-construction background noise curves and noise limit curves to assess compliance.

ROAD AND RAILWAY NOISE

Noise impact assessments are essential for all road and rail projects. MACH Acoustics can assist in the planning and design of road and rails project. Our capabilities include:
   •   Noise impact assessments
   •   Traffic noise measurements
   •   Noise level prediction using established prediction methods (CRTN/CRN)
   •   3-dimensional computer modelling for noise contour plots and preliminary noise barrier design

INDUSTRIAL NOISE

MACH Acoustics can help in solving noise issues and problems for a range of industrial and commercial applications. We are able to provide the following services:
   •   Occupational noise surveys (Control of Noise at Work Regulations 2005)
   •   Industrial noise assessment (British Standard 4142 Environmental Agency (EA) IPPC H3 Noise Guidance)
   •   Noise abatement using enclosures, silencers and noise barriers

For more information about MACH Acoustics’ environmental acoustics services please contact our office on
0117 944 1388.

Posted by IT MACH

Open Plan Teaching

3rd September 2010BB93, Breakout Spaces, External Spaces, Learning Plazas, Library Spaces, Open Plan, Open Plan Spaces, Open Plan Teaching, Shared Resource Areas

Open plan teaching is becoming increasingly popular due to the benefits offered by this form of teaching and learning environment. Open plan spaces offer increased levels of flexibility, sharing of resources, cross learning between teachers and between pupils, enhanced visual and auditory communication as well many other educational benefits.

Alsops open plan teaching space option 1

Open plan within the educational environment can take many forms; learning plazas, breakout spaces, library spaces, shared resource areas, external spaces etc. These spaces have a diverse range of requirements and needs. In addition to this, open plan teaching is carried out from reception years right through to higher education, and then of course onto our working environment. This further increases the range of requirements and diverse needs relating to these types of spaces.

Alsops open plan teaching space option 2

Often, a limiting factor of open plan spaces is poor acoustics. In MACH Acoustics view, this shortfall is due to two main factors; insufficient importance given to the acoustic design of the spaces (i.e. not employing a good consultant) and a lack of understanding of the specific needs of a learning space. It is MACH Acoustics view that the starting point in the design of an open plan space is to understand what is required from the space and its specific educational needs. Once these are understood, the acoustics design can be established and such to ensure that these requirements are met and that the clashes between acoustics and open plan can be resolved.

BB93 ‘Acoustic Design of Schools’ provides some basic requirements with respect to open plan and these requirements are covered in Section1.1.7 Speech intelligibility in open plan spaces. In summary, this section states that the speech intelligibility level and sound transmission index (STI), are required to be above 0.6 and 1 respectively. The STI of a space is determined through detailed software calculations.

BB93 ‘Acoustic Design of Schools’ also provides advice in the form of case studies which are presented in Case Study 7.2 – An investigation into the acoustic conditions in three open-plan primary schools (BB93 Page 97) and Case Study 7.3 – Remedial work to an open-plan teaching area in a primary school (BB93 Page 107). These case studies look at the effects of acoustic treatments, acoustic screens, seating layouts and other aspects. It is MACH Acoustics view that this information is relatively limited and that better, simpler and more flexible solutions can be found.

MACH Acoustics has undertaken a number of projects containing open plan spaces ranging from open plan breakout spaces in primary schools through to full plazas providing the full educational spectrum to 60/90 secondary school pupils at a time. Two of these spaces include the New Line Learning Plaza and the New Line Learning Plaza 2 at Oldborough School, Kent. Case studies on these two schools are presented within this PDF document – Open Plan Teaching.

In addition to these projects, MACH Acoustics is working alongside White Design and Monmouthshire County Council in the design of two key educational open plan facilities; Green Lane Primary School and Castle Park Primary School. Using this blog, MACH Acoustics will be presenting our designs as they progress.

Posted by IT MACH

Lecture Theatre Design – Bath University – Part I

3rd September 2010Lecture theatre, Reverberation time, Room Acoustics

Hello, I’m Andrew, one of the eight people working at MACH Acoustics. I’ve recently been involved in a project for Bath University. MACH Acoustics were asked by ADP Architecture and Cowlin Construction to work on the acoustic design for a 350 seat lecture theatre. Obviously speech is the important element in a lecture theatre and I thought for this post I’d explain some basic guidelines to follow when conceiving plans for auditoriums used for speech.

Design Factors

The key factors to address when designing a space for speech are:

1. Providing an optimum reverberation time.
2. Eliminating acoustic defects such as echoes and flutter echoes.
3. Maximizing loudness in the audience.
4. Minimizing noise levels in the design space.
5. Providing a speech reinforcement system where needed.

Our design intent for Bath University was to provide a lecture theatre without the need of providing a speech reinforcement system so we didn’t need No. 5.

No.4 is dependent on the sound insulation separating the lecture theatre with all adjoining spaces, plus any Mechanical and Electrical (M&E) services noise within the space, these are relatively simple to control. No.2 is primarily concerned with late reflections and flutter echoes. These effects are usually dealt with by the placement of acoustic treatment which is required to satisfy No’s.1 & 3.

Providing an optimum reverberation time

Different types of auditoria require different acoustic performance criteria. One fundamental criterion is the selection of the optimum reverberation time (RT) – or the length of time it takes for sound to decay by 60dB. Long RT’s are desirable for musical performances but tend to interfere with the spoken voice making intelligibility levels lower. Hence, speech specific auditoria require a relatively short RT. A useful guide to selecting the required RT is provided graphically below:

Placement of acoustic treatment

The images below provide generic design advice with respect to the positioning of soft treatments within an auditorium. The surfaces to the rear of the auditorium are typically made soft and absorptive to control the extent of reverberation. This rear location also stops late reflections bouncing off the rear wall and being heard as a notable echo by the front row of audience. The amount of soft treatment required will depend on the absorptive properties of the materials used, the volume of the hall and the chosen reverberation time discussed above.

(A note to consider where long reverberation times are required, such as musical spaces, is that little to no additional soft treatments are then required. This can expose the rear wall and cause undesirable echoes which the audience will hear. To combat this rear walls can be made diffuse. This is done by making the surface irregular. Off the shelf products may be used or bespoke by using varying sizes of projected wooden battens. The purpose being to scatter the sound in many diverse directions compared to a single strong reflection.)

Surfaces to the front of an auditorium should be hard to enhance early reflections and increase loudness for the audience.

Methods of maximising loudness/volume and how these were adopted for the Lecture Theatre at Bath University East Building will be discussed in my next post.

Posted by IT MACH

BaleHaus @ Bath – Modcell Acoustic Testing

18th August 2010Acoustic Testing, Eco Buildings, Sustainable Acoustics

The BaleHaus @ Bath University

MACH Acoustics has recently conducted sound insulation testing at the BaleHaus at the University of Bath. The BaleHaus project is research program being coordinated by the Department of Architecture and Civil Engineering.

The BaleHaus is constructed from Modcell. The ModCell system utilises the excellent thermal insulation qualities of straw bale construction to form prefabricated panels constructed locally to reduce energy requirements for transportation.

As a supporter of low-energy, sustainable design, this project was of great interest to MACH Acoustics. We were thrilled when be asked to be involved in the ongoing research into the properties of this ‘carbon-negative’ construction material.

The acoustic testing was conducted according to ISO 140-5:1998. The presence of building management system controlled window within the test room required careful consideration when planning for the test. To avoid the effects of sound transmission through this element, the entire window frame was sealed using the two layers of 15mm Soundbloc fixed to a partially de-coupled frame. Testing was also conducted with the window frame unsealed for comparison purposes.

Testing in progress

The results of the testing found that Modcell is a suitable facade material for all but the most challenging noise environments. The analysis found that the internal noise level was governed almost entirely by the noise transfer through the window.

More information about the BaleHaus and Modcell can be found by going to www.modcell.com

Posted by IT MACH

Natural Ventilation Feasibility

16th August 2010BB93, BREEAM, NAT Vent Attenuator, Natural Ventilation, Vented Facades

As per the introduction to this blog, MACH Acoustics aims to provide a useful blog providing ideas, details and knowledge, where people can discuss ideas and hopefully move forwards in a more suitable and low carbon way.

MACH Acoustics has recently published four conference papers on the acoustic design of low energy buildings. Subjects covered are the acoustic performance of open windows, the design of high performance natural air vents, the onsite performance of corridor walls and methods of achieving cross ventilation. We are currently working on a 5^th paper looking at acoustic treatments in combination with thermal mass cooling.

The starting point for this blog will therefore be a description of these papers. The titles of each of the papers are listed below. There is also a link to a PDF copy of these papers below.

Acoustic Scaled Models and Naturally Vented Facades
NAT Vent Cross Talk Attenuator
NAT Vent Attenuator and Facades
Acoustic Performance of Open Windows

Green acoustic consultants probably have the greatest effect on a buildings carbon emission when reviewing the design of vented facades. This element of design is also likely to have the most significant impact upon the level of energy used by a building.

The graph below provided by Brent Associates Architects presents key information with respect to the energy consumption of building types and their location. This information in turn demonstrates how best to reduce the energy consumption of buildings.

Figure 1 – Energy consumption for a range of building types and their location

This graph shows that the greenest buildings are those that incorporate three elements; natural ventilation, a town or city centre location and the reuse of a building in the form of a refurbishment. This conclusion is made on the basis that natural ventilation is significantly more energy efficient than mechanical ventilation (1 to 2 Figure 1). A city centre location for a building reduces a significant chunk of the buildings carbon emissions as a result of reduced transportation (2 to 3). The third significant reduction in energy is achieved through refurbishing a building. Here, the embodied energy required to form a building is not needed and hence this is a significant design goal for low energy building design (3 to 4).

With respect to acoustics, these requirements make things difficult. It is always complex and more complicated to refurbish a building. The difficulties arise as a result of reduced levels of flexibility in terms of design, structural constraints, facade restraints, planning, historical limitations, as well as other factors. As consultants we therefore need to be more creative and have a wide range of products and/or designs to overcome these limitations.

Locating the building within a city or town centre will always bring issues with respect to noise break in. The figure below shows a noise map taken from www.noiserus.com. Table 1 shows the percentage of land where it is possible to comply with BREEAM and BB93 internal noise levels when a building is ventilated by means of opening windows. The sound reduction of an open window is assumed to be 10 dBA.

Figure 2 – Town centre noise map provided by www.noiserus.com.

Table 1 – Percentage of sites available within town centres, where simple openable windows provide adequate levels of acoustic resistance such to comply with BREEAM and BB93 requirements.

Space	Target Noise Level	Percentage of site suitable for natural ventilation
BREEAM – single occupancy offices	<40 dBA	41%
BREEAM – multiple occupancy offices	40-50 dB L_Aeq,T	47%
BB93 – classroom	35 dBA	22%
BB93 – lab/workshop	40 dBA	41%

It is clear from the figure above that the development of green buildings within towns and city centre locations, will more often than not require acoustic solutions which provide high levels of acoustic attenuation to environmental noise break in.

My next entry will therefore look at methods of increasing the acoustics resistance of vented facades.

Posted by IT MACH

Welcome to MACH Acoustics Blog!

4th August 2010Architecture, Construction, Eco Buildings, Exhaust Stacks, Sustainable Acoustics, Ventilation Systems

The aim of MACH Acoustics is to become one of the leading acoustic consultants in the field of sustainable building design. This aim means that we specifically focus on projects around sustainable architecture and Eco buildings. A considerable portion of our time is therefore spent looking to solve some of the conflicts between acoustics and low carbon, sustainable constructions.

Acoustics and sustainability are not often spoken about together. On the other hand, air conditioning systems are often used to overcome noise ingress issues. Thermal mass cooling; exposed concrete soffits for example, can make buildings sound loud, harsh and noisy. Cross ventilation, exhaust stacks and other air ventilation systems can compromise the acoustic cross talk between office buildings accommodation and teaching spaces within educational buildings. Vented facades in combination with ventilation louvers and other types of air ventilation systems within the fenestrations of a building are often used to prevent noise ingress. Buildings are often built using high mass structures to achieve acoustic requirements.

These factors clearly show the link between acoustics and sustainability. Acoustics can therefore have a significant impact upon the levels of carbon emissions, ventilation system and the level of embodied energy in the buildings frame and other factors affecting the sustainable architecture of a given building. With changes to Building Control Documents Part L and Part E, along with new client expectations, there is an increasing importance to ensure that building designs become more integrated and greener.

MACH Acoustics view is that the best way to overcome the limitations imposed by acoustics on sustainable buildings is to increase our knowledge base. This simple goal is therefore the aim of this blog. We aim to provide a point of reference where detailed information will be regularly uploaded relating to residential buildings and the code for sustainable homes. We will be looking at Eco buildings and acoustic materials which match requirements for sustainable building design. Ventilation systems including vented facades, acoustic ventilation louvers, attenuators within facades, passive house systems, heat recovery systems, exhaust stacks and other air ventilation system will be discussed over time.

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