dBx Acoustics

3 Things We Should Put Right in Residential Acoustic Design

Sounding Off – Acoustics in Residential Design

At first glance, it seems as though residential development is one of the few area where there is a clear, documented requirement for acoustic design. From planning noise impact, through to design and pre-completion testing in accordance with Approved Document E of the Building Regulations. There’s a standard which needs to be complied with. Why, then, are there still so many noise complaints from residents?

In our opinion, three main things need to be put right in residential acoustic design.

Planning

BS 8233:2014 sets standards for internal noise levels in residences (from external noise sources) which allow appropriate conditions for rest and sleep. These standards are compatible with World Health Organisation recommendations and strike a good balance between health and amenity, and practicality. The problem is local authorities are patchy in whether and how they require developers to demonstrate that the standard is met.

From the developer’s point of view, commissioning an acoustic assessment for planning can lead to additional costs if it shows that natural ventilation via open windows isn’t an appropriate solution. It’s therefore vital that the Local Planning Authority take responsibility in ensuring the appropriate design of all new residential developments. Whilst it might increase initial costs to the developer, the relative savings in terms of residents’ health and well being should outweigh this.

Design Standards

Approved Document E (ADE) sets airborne (controlling e.g. voices and music) and impact (e.g. controlling footfall) sound insulation standards between residential units. However, in our opinion, the acoustic standard required by Approved Document E isn’t a high one. We often investigate sites where there are complaints of noise disturbance, where we find that ADE has been met.

We’ve noticed an increasing trend for developers to require that ADE exceeds by at least 5 dB. This seems to provide a greater perception of quality for potential tenants as well as reducing the likelihood of disturbance. The uptake of this enhanced performance criterion suggests that it does not significantly impact developer costs. This makes us wonder whether the next revision of the Building Regulations will see this built in as a requirement.

(Don’t!) Do It Yourself

Finally, something we see often is a developer who believes they can design and build in compliance with ADE without consulting an acoustician. Developers who build multiple units on multiple sites to a standard design can certainly get away with this. However, more bespoke sites or refurbishments are fraught with danger for the unsuspecting. Acoustic separation between units is controlled not only by the specification of the partition, but also by how it connects to the partitions around it, and by any sockets and pipework. Did you know you also need to provide some reverberation control to common areas? How about the acoustic requirement for corridor walls and doors? Is the acoustic performance of your separating floor going to be compromised by those recessed lights?

Getting to completion, then failing the acoustic testing required by Building Control is an expensive mistake. There’s no ‘quick fix’ product. This often means significant demolition of the partitions you so lovingly installed to solve the problem. If in doubt, you should engage an acoustic consultant to help you through the design before going on to pre completion testing.

Do You Need Help?

Whoever you turn to, be sure that they are appropriately qualified. Individual acoustic consultants should be members of the Institute of Acoustics (MIOA). To carry out pre-completion testing, consultancies should have either a UKAS or the Association of Noise Consultants (ANC) accreditation.

If you need help and advice with any aspect of residential acoustic design, from planning through to testing, dBx Acoustics would be happy to help!


dBx Case Studies - Education

There is a proven link between acoustic conditions in schools and educational outcomes. Building Bulletin 93 (BB93) mandates minimum standards in primary and secondary schools for noise levels and room acoustics, as well as acoustic separation between teaching spaces.

The dBx Acoustics team can help you comply with BB93, but our expertise goes even further. We have extensive experience designing environments for pupils with additional needs, including autism and hearing loss, as well as higher education and noisier, practical workshop spaces.

New and refurbished school buildings must comply with Building Regulation E4 and the acoustic performance standards of Building Bulletin 93 (BB93) ‘Acoustic Design of Schools’. Whilst BB93 is not mandatory for higher education establishments, it typically forms the basis of the initial design for such establishments, with modifications as appropriate to allow for specific HE uses. Where projects are being designed with BREEAM in mind, credits HEA05 and POL05 are also relevant.

There are a number of different acoustic aspects which come together to ensure that acoustic conditions in schools are appropriate to support learning, and it’s so important to get it right – studies have shown that educational attainment can be directly correlated to acoustic conditions.

Our involvement often begins at the planning stage with an environmental noise survey, which allows us to advise on ventilation and glazing requirements to control noise ingress to the building. If mechanical ventilation is proposed, if there is an external MUGA, or if community use is proposed, the noise survey also allows noise emission limits to be set to ensure that existing neighbours are not adversely affected by noise.

Internal ambient noise levels in teaching spaces are also affected by mechanical ventilation, and we work with the M&E consultant to specify appropriate noise control measures, such as silencers.
When it comes to the design of the building itself, BB93 requires us to specify partitions and floors to control airborne and impact sound transmission between teaching spaces, based on their relative sensitivity and noise generation characteristics. The detailing of junctions and sealing of any services penetrations is critical in maintaining acoustic separation between adjacent rooms.

Having provided a suitably quiet teaching environment which won’t be adversely affected by activity in other classrooms, our focus moves to room acoustics and control of reverberation. Often this is as simple as specifying the acoustic performance of a suspended ceiling, but for large spaces such as Assembly Halls and Sports Halls, we undertake acoustic modelling to optimise the specification and placement of acoustic finishes. Where an exposed soffit is preferred, we calculate the specification and quantity of finishes, such as acoustic rafts and wall panels to control room acoustic conditions.

Finally, we carry out pre-completion acoustic testing on-site to ensure that all of the acoustic criteria for the project have been complied with on-site.

The dBx Acoustics team also have a particular interest in acoustic design for SEN schools, particularly schools catering to neurodiverse pupils. BB93 specifies design criteria for “children with special hearing and communication needs”, which is intended to include autism, ADHD and auditory processing difficulties, and assists in providing an environment in which speech transmission is clear and effective. The standard does not, however, consider the other acoustic aspects of school life which affect such pupils, including auditory sensitivities and the need to provide spaces to allow a retreat from the noise and bustle of daily school life. Our team’s direct and personal experiences of neurodiversity, both as parents and as individuals, helps us to understand the requirements of individual educational clients, and help guide the design of educational buildings to provide an acoustically diverse and appropriate environment.

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