The British Standard BS 4142:2014+A1:2019 Methods for rating and assessing industrial and commercial sound is used for investigating noise complaints, assessing sound from proposed, new, modified or additional source(s) of sound of an industrial and/or commercial nature and assessing sound at proposed new dwellings or premises used for residential purposes.
What an earth does all that mean and why should you care?
In a nutshell if you own, manage or are in any way responsible for an existing premises that is causing a noise nuisance from plant, equipment or machinery, this is the standard a Local Authority will work to. Similarly, if you want to build a new premises or extend an existing premises where noise could impact on neighbouring properties this is the standard the Local Authority will work to.
Environmental Health teams investigate noise complaints and may require a noise impact assessment (NIA), and it is often a requirement in the planning process.
So, what is involved?
The key to a NIA is the background sound level, which simply put is the sound for 90% of a set period of time without the noise source, this has to be correct. The standard gives a considerable amount of guidance on how, where and when to measure the background level.
The existing noise source is measured, or a proposed noise source is assessed using the manufacturers data and then compared to the background level. Pretty straight forward, life is rarely so. There are frequencies, on times, character correction and many other considerations which lead to a rating level of the noise source or specific sound.
The background level is subtracted from the rating level and if you are lucky you are left with a negative number. Some LAs required the rating level to be 10 dB below the background level, how is that even possible?
If you have a background level of 50 dB from rustling leaves and birds singing and a noise source of 50dB from a fan then they are completely different sounds and you will hear both, however, if the noise source is 40 dB you are unlikely to hear the fan.
The rating level is assessed based on impact, the greater the exceedance above the background level the higher the impact. A low impact is where the rating level does not exceed the background level, +5 dB indicates an adverse impact and +10 dB or more indicates a significant adverse impact, all subject to context (that’s a whole other story).
Okay so you have your assessment, it is low impact and meets the LA’s requirements, happy days, but what if it is adverse or significant adverse impact? For existing sources mitigation measures are required, for new builds go back to the drawing board/computer and see if through good design and planning the rating level can be reduced.
My advice;
- If you receive a noise complaint, take it seriously and try to nip it in the bud before it even gets to the LA, but if it has again do not leave it, you do not want to be served with a Noise Abatement notice.
- If a development is going to introduce a noise source to an area or be in the vicinity of a noise source, consider noise. Often the issue of noise is raised very late in the day and can cause delays and increase costs.
We have conducted multiple Noise Impact assessments arising from noise complaints or the planning process, including for battery storage facilities, sub stations, grain driers, kitchen extraction systems, air source heat pumps, warehouse activity and night clubs. We have recommended mitigation measures that have resolved noise complaints and satisfied planning requirements. We provide robust assessments and reports to ensure positive outcomes.
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