Project Description

A plant noise assessment is normally requested at the planning stage to assess the impact of noise levels from proposed plant and machinery on nearby noise sensitive locations. This can apply to many different types of developments where noise levels from associated plant and machinery are off concern. The common method to assess such noise in a noise sensitive area is to carry out an assessment in accordance with BS 4142:1997 “Method for Rating Industrial Noise Affecting Mixed Residential and Industrial Areas” (BS4142).

This British Standard 4142 involves measuring the existing background noise level at the nearest noise sensitive locations for a period of at least 24 hours or over the proposed operational hours of the plant.  The noise levels from the proposed plant are then compared to the existing background noise levels for both the day and night time periods in order to assess the risk of complaints.

The likelihood of complaints in response to a noise depends on various factors. BS4142 assesses the likelihood of complaints by considering the margin by which the noise in question exceeds the background noise level. This standard also allows for an appropriate correction for the acoustic features present in the noise source.

In accordance to BS4142, the likelihood of noise complaints for plant noise break out is a function of the difference between plant noise levels and existing background noise levels at the nearest sensitive location. BS4142 states that:

  • A difference of around +10 dB or more indicates that complaints are likely.
  • A difference of around + 5 dB is of marginal significance.
  • If the rating level is more than 10 dB below the measured background noise level, then this is a positive
    indication that complaints are unlikely.

To assist in planning applications Aran Acoustics can carry out a noise survey to establish the noise levels representative of the nearest sensitive location to the proposed plant location. We assess the noise levels created by the proposed plant and evaluate the suitability based on the measured background noise levels. If required, we will provide advice as to how noise emissions can be mitigated. We can liaise with the planning officer to ensure that our methods are accepted and that the planning requirements are included within our calculations and meet their needs. A report documenting our measured noise levels along with our conclusions and design advice will be provided, suitable for discharging any planning conditions.