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  • Samantha Hathway

The Importance of BS 4142 Noise Assessment

In any urban environment, development of residential and commercial premises, as well as industrial innovation, continues to constantly evolve the landscape. But as we all know, noise pollution is one of the main stressors in society today, and for this reason developers and businesses need to follow strict criteria when it comes to the noise levels they generate. In order to protect sensitive premises, such as residential buildings, schools and hospitals, the likely impact of industrial and commercial noise is assessed using the British Standard BS 4142:2014.

When should a BS 4142 noise assessment take place?

When it comes to assessing the impact of industrial noise on the surrounding environment, in particular where there are existing or proposed residential developments involved, sophisticated assessment is required, and this is where the BS 4142 applies.

British Standard 4142:2014 ‘Methods for rating and assessing industrial and commercial sound’ is one of the UK’s most widely used standards for assessing environmental noise in mixed use areas.

The standard can be used to protect noise-sensitive buildings – such as residential dwellings, schools, hospitals and hotels – from existing and proposed commercial and industrial noise sources. The standard can also be used to help local authorities assess whether proposed residential developments can be built in areas where existing commercial and industrial noise is present.

The remit for BS 4142 includes sound from the following sources:

  • Fixed installations and power plants, including electrical and mechanical equipment such as extractor fans and factory step lifts

  • Industrial and manufacturing processes

  • Unloading and loading of goods at the premises

  • Mobile plants and vehicles that form an intrinsic source of noise from the premises, such as forklift trucks

The assessment will sometimes need to take place at the pre-application phase for commercial and housing development, depending on whether the local Council considers the surrounding area to be at risk from potentially high levels of commercial and industrial noise pollution.

However, sometimes a survey is required, for example where complaints have been received. Given the costs and time delays associated with putting mitigation measures in place, not to mention the punitive financial impact of having to temporarily close a site down, it’s important to ensure your site follows legislative guidelines.

How is potential noise disturbance assessed using BS 4142?

Assessment of noise levels is undoubtedly very subjective and impacted by many factors. These include the type of neighbourhood affected, the time of day, duration of noise exposure and the extent that sound levels exceed background noise levels.

The BS 4142 assessment uses a ‘rating level’ that compares the sound being assessed with the background noise that would exist without the sound source. The following steps are undertaken:

  1. Baseline measurements are taken to assess the background noise level, without the proposed or operating noise source being in operation.

  2. Noise emissions from the operating source are taken; for proposed premises, acoustic modelling is used to predict noise levels.

  3. The noise impact is analysed using BS 4142, and the resulting rating level is then modified using corrections for the character of the sound, be that tonal, impulsive or intermittent. Finally, the BS 4142 impact assessment takes account of the ‘context’ in which the sound will be heard.

Once the analyses have been completed, and the noise levels corrected for acoustic features, the background sound and emanating sound are compared. According to the standard:

  • Typically, the greater this difference, the greater the magnitude of the impact

  • A difference of around +10 dB or more is likely to be an indication of a significant adverse impact, depending on the context

  • A difference of around + 5dB is likely to be an indication of an adverse impact, depending on the context

  • The lower the rating level is relative the background sound level, the less impact the noise will have on the surrounding environment. Where the rating level doesn’t exceed the background sound level, the sound source will generally have a low impact, depending on the context.

Following the assessment, the professional body undertaking the survey will provide a technical report that can be submitted to the local authority to support a planning application. Noise-related planning conditions are frequently attached to planning approvals, these will need to be adhered to and will be assessed prior to final approval for on-site operations to commence. Occasionally, post-completion noise surveys will also need to be conducted, to ensure that noise standards have been achieved.

Where a site is already in operation, the technical report will also recommend mitigating measures, to bring the noise levels in compliance with necessary requirements.

Who can carry out a noise assessment survey?

Noise impact assessments are usually conducted by an Acoustic Consultant. When it comes to the assessment of commercial and industrial noise in accordance with BS 4142, you can see that it’s not just a case of taking and comparing readings, it’s about understanding that every acoustic landscape is unique. This is where it’s vital to use the services of a professional acoustic consultancy, such as us here at Auricl. By taking into consideration specific acoustic features and the context of the sound, our Acoustic Consultants use their extensive experience to accurately assess the impact of noise on the surrounding environment. After all, when it comes to BS 4142 in particular, the circumstances can influence whether a noise source is high or low impact, so professional judgement is key.

If you need help with your planning application, or to mitigate a noise complaint for your commercial or residential development, then don’t hesitate to contact us. We have experts in place that can help assure the smooth running for your commercial operation, ensuring you remain compliant with the standards required by Government bodies and local authorities. If you need a noise assessment survey conducted within the London area, contact our team on 020 7859 4530. For the South East, contact our Reading office on 0118 207 7324, or get in touch by emailing

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