BS 4142 Industrial & Commercial Noise Assessment
BS 4142:2014+A1:2019 sound rating of industrial and commercial noise sources at residential receptors. Specific sound level vs background, character corrections for tonality and impulsivity, context assessment and mitigation design.
The standard methodology for fixed-plant planning applications
BS 4142:2014+A1:2019 is the UK industry standard for assessing industrial and commercial noise at residential receptors. It applies to fixed plant (HVAC, chillers, refrigeration, generators, extract systems), industrial process noise, warehousing and logistics noise, commercial kitchen extract, refuse collection and waste handling, and any other industrial / commercial sound source.
The methodology compares the specific sound level of the source (with character corrections for tonality, impulsivity, intermittency and other identifiable features) to the residual background sound level, producing a rating level whose difference from background dictates the magnitude of impact: +5 dB indicates an adverse impact, +10 dB a significant adverse impact, and a -10 dB rating indicates low impact. Context is then applied to refine the conclusion.
We carry out BS 4142 assessments for planning applications, permit applications (EPR), discharge of pre-commencement conditions, complaint investigations and post-installation verification. Reports use Class 1 instrumentation, field-verified calibration, full meteorological context and proportionate mitigation recommendations where the rating exceeds the adverse-impact threshold.
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Planning Stage BS 4142 Assessment
Pre-application or planning-submission BS 4142 with predicted specific sound levels from manufacturer data, modelled background based on a baseline survey, and mitigation specified at design stage rather than retrofit.
Post-Installation BS 4142
Measured BS 4142 once plant is commissioned, with full meteorological context and the character corrections (tonality, impulsivity) applied as observed. Used to discharge conditions and to demonstrate compliance.
Complaint Investigation BS 4142
Where environmental health has received complaints, an independent BS 4142 documents the actual rating level and the cause — whether the source is the issue, the background has changed, or character corrections are driving impact.
Industrial Estate & Multiple Sources
For sites with multiple plant items or cumulative operations, BS 4142 with source-by-source breakdown and a combined rating assessment.
Commercial Kitchen Extract Acoustic
Combined acoustic and odour assessment of commercial kitchen extract systems — BS 4142 noise for the receptor analysis alongside the EMAQ+ odour assessment we provide for the cooking emissions.
Refrigeration & HVAC Plant
Specialist assessment of refrigeration plant, chillers, AHUs and rooftop HVAC with tonality character correction (where compressors and fans contribute discrete-tone components above background).
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Frequently Asked Questions
When do I need a BS 4142 assessment?
Any planning application or permit involving industrial or commercial fixed plant near residential receptors will typically require a BS 4142 assessment. Common triggers include new commercial kitchen extract, new HVAC plant, generators, refrigeration units, industrial estates near residential, waste transfer stations and commercial refuse handling.
What rating level is acceptable under BS 4142?
BS 4142 does not set fixed acceptability thresholds — it produces a rating level whose difference from background indicates magnitude of impact. A +5 dB rating indicates adverse impact; +10 dB indicates significant adverse impact; -10 dB indicates low impact. The local authority then takes a planning decision in the context of the magnitude and the wider proposal.
What are character corrections?
BS 4142 applies corrections for identifiable sound character: +3 dB for clearly tonal (whining, humming), +6 dB for highly tonal; +3 to +9 dB for impulsivity; +3 dB for clear intermittency; +3 dB for other identifiable features. Tonality is the most common in HVAC, refrigeration and process plant.
How is background determined?
A baseline noise survey establishes the LA90,T residual background sound level at the receptor during the relevant assessment period (typically daytime and night-time, occasionally evening). The survey must cover representative conditions over enough time to capture the genuine background — usually 24 to 48 hours minimum.
How much does a BS 4142 assessment cost?
A typical single-source BS 4142 assessment for planning (one receptor, daytime + nighttime, with report) starts from around £1,500 to £2,500 plus VAT. Multi-source industrial estates or complex sites with multiple receptors typically £2,500 to £4,500.