In this blog post, we are going to look at noise impact assessments. In particular, what they are, why we need them and how we conduct them.
So, what are they? A noise impact assessment is a way of understanding the effect that a noise source will have upon the local acoustic environment. This is needed to protect local residents and to prevent annoyance due to noise.
The British Standard BS 4142:2014 (Methods for rating and assessing industrial and commercial sound) is used. You can learn more here. This sets out the measurement methods which should be followed when conducting noise impact assessments. Unless otherwise requested by the local authority, this is the method that will be used.
The standard is used for proposed, new, modified or additional noise sources. When a planning application is submitted to a local authority including one of the above, a noise impact assessment should be requested.
Within the impact assessment, there are many factors which need to be considered. Firstly, the existing background noise levels at the nearest residential properties (also known as the Noise Sensitive Receptor or NSR) need to be defined. Generally this is in the form of a long term noise survey covering several daytime and night time periods. This is termed the ‘background sound level’.
The next stage involves the calculation or measurement of the noise level generated by the proposed noise source as observed at the NSR. If the equipment is already installed, this is done by taking acoustic measurements at the residential property with and without the noise source active. From these measurements we can calculate the background noise and the noise generated by the source. This is known as the ‘rating level’. In occasions where the equipment has not yet been installed, a prediction model can be used to estimate the rating level at the NSR.
There are also penalties applied for characteristics of the sound. For example, if a sound is very impulsive, like a hammer drop, a penalty is applied. A similar penalty is added for very tonal sounds.
BS 4142:2014 provides guidance on the expected level of noise impact. This is based on the difference between the background sound level and rating level. If the rating level is 10dB higher than the background sound level ‘significant adverse impact’ is expected. Where the difference is 5dB, an ‘adverse impact’ is expected. The lower the rating level is vs the background sound level the less likely that an adverse impact will be observed.
In instances where a significant or adverse impact is expected, corrective measures will be required before the planning application is approved.
At NCSL, we provide services to complete noise impact assessments in full. This also includes remedial work as and when required. If you would like any further information, or would like to discuss a noise impact assessment with our experts, please contact us.
We have years of experience in noise impact assessments. And our acoustic consultants are highly skilled in noise control methods. This allows us to guide our clients throughout the process with minimal disruption.
You can find more info on our Services page. Feel free to Contact us to discuss a noise impact assessment with our consultants. As each case is different, it is not possible to provide a set price for an assessment. However, our prices are extremely competitive. Plus, we endeavour to beat and like for like quotation. We look forward to working with you.