BS 4142 has been used to provide guidance relating to the impact of noise from industrial sources for the past few decades. Last revised in 1997, the British Standards Institute (BSI) has decided that the current version be assessed and updated. Consequently BS4142:2014 was released in October 2014 to officially supersede the 1997 edition.

Many Local Authorities have historically used the BS 4142 guidance to set noise limits for new and existing industrial installations despite it not originally being written for planning purposes, but to assess the likelihood of a noise source giving rise to complaints. The 2014 revision expands its remit and describes methods for rating and assessing sound of an industrial and/or commercial nature for the purposes of:

1. Investigating complaints
2. Assessing sound from proposed, new, modified or additional sources of sound of an industrial/commercial nature, and;

iii)                Assessing sound at proposed new residential premises.

Significant changes that have implications on consultants, clients and local authorities alike, include:

• the removal of the phrase “Affecting mixed residential and industrial areas” from the title, effectively broadening the situations to which the standard is applicable;
• placing far greater emphasis towards the “context” of the sound. Noise is routinely considered to be sound that is undesirable or intrusive;
• the inclusion of “commercial sound” not just industrial sound. The 2014 edition should also be applied to sound from the unloading of goods, as well as mobile plant and vehicles that form an intrinsic part of the operation of industrial and/or commercial sites;
• the assessment of the impacts – In the 1997 standard there was a 15dB separation between assessments of “marginal significance” and “a positive indication that complaints are unlikely” – with little or no guidance in-between. The new standard removes the complaints’ likely/unlikely interpretation and replaces it with:

1. i) A difference of around +10 dB or more is likely to be an indication of a significant adverse impact, depending on the context
2. ii) A difference of around +5 dB could be an indication of a significant adverse impact, depending on the context

iii)           The lower the rating level is relative to the measured background sound level, the less likely it is that there will be an adverse impact.

Note: It is also necessary to consider the context by considering:

• the absolute level of sound and background sound level;
• the character and level of sound;
• the sensitivity of the receptor and whether the residential premises incorporate design measures that ensure good internal acoustic conditions.