BS 4142 “Method for rating industrial noise affecting mixed residential and industrial areas”

British Standard BS 4142:1997 is the standard normally used in the UK to assess whether noise from factories, machinery and industrial or commercial premises is likely to give rise to complaints from people living nearby.  The standard is based on the principle that the likelihood of any complaints depends on the noise level of the factory or plant relative to the background noise when the factory or plant is not operating.

The noise level of the industrial plant, referred to as the ‘specific’ noise level, is measured at the assessment location, normally outside a nearby residence. The ‘background’ noise level at the assessment location is also measured at a time when the specific noise source is not operating. 

If there are distinguishable acoustic features present in the specific noise level, (hums, whistles, bangs, clicks, clatters or thumps) or the noise is irregular enough to attract attention, then a 5 dB penalty is added to the specific noise level in order to obtain the ‘rating’ level.

As general guidance, if the rating level is more than 10 dB above the background level, this is an indication that complaints are likely. If the rating level is 5 dB above the background, this is of 'marginal significance' and complaints are possible.  Hence, the lower the difference between the rating and background levels, the less likelihood of complaints.  However, many Local Authorities suggest their own recommended level differences irrespective of the guidance contained in the standard.

ISVR Consulting carries out assessments of industrial noise using BS 4142 and can also offer cost effective noise control solutions and designs to minimise noise reaching nearby residents, and thereby to minimise any adverse comments or complaints.

British Standard BS 4142 is currently being substantially updated and revised. The new version, will be published in 2014, replacing the 1997 version.