Noise Impact Assessment
Planning conditions for all new developments, especially residential, schools and healthcare, require a noise impact assessment. A Noise impact assessment involves comparing the predicted noise levels from the proposed development against the prevailing background noise levels.
By measuring existing noise levels in an area, we can establish an appropriate noise level for new noise sources to avoid disturbance and ‘noise creep’. We also calibrate noise maps (see below) to show how sound propagates across a built up area.
Noise surveys are used to assess the impact of environmental noise on a new development, particularly residential developments, where they allow us to establish the acoustic strategy for ventilations and facades (BS 8233 assessment).
Where new noise sources will be introduced, noise surveys are the basis for a BS 4142 assessment (see below) to establish the level of disturbance occasioned to surrounding premises.
BS 4142 Assessment
BS 4142 is the standard used to assess the potential for disturbance arising from industrial and commercial noise sources. In a BS 4142 assessment, the noise from an existing or future noise source is compared against the existing background sound level. Penalties are applied for acoustically distinctive characteristics such as intermittency or tonality. Based on the difference between the ‘rating level’ and background and considering the acoustic context of the area, the likelihood of disturbance to surrounding areas can be predicted.
A BS 4142 assessment is usually required at planning stage for new industrial and commercial noise sources. It can also be carried out where noise complaints are received to investigate whether there is a basis for the complaints.
Noise Mapping and Modelling
For complex sites, noise modelling is a great way to investigate how new noise sources will affect the surrounding area. Models allow us to consider factors such as the landscape, screening from buildings and the location of new noise sources.
We calibrate models using the data gathered from noise surveys, which means multiple noise sources in an area (e.g. roads, industry, rail) can be accurately represented. Models also allow us to optimise mitigation measures such as bunding and noise barriers, saving money for the client while making sure the surrounding area is appropriately protected from noise.