Noise Impact Assessment
Has the council requested a BS4142 or BS8233 report before your application can progress?
We resolve noise objections with BS4142/BS8233 Noise Impact Assessments, mitigation design, and council/EHO/EA liaison.
Independent reports led by Chartered engineers
Environmentally Sound Limited provides independent Noise Impact Assessments (NIA) that help unlock approvals and de-risk projects. Each assessment is led by our Chartered Mechanical & Acoustic Engineers, and we bring in trusted specialists when required — ensuring the work is accurate, defensible, and tailored to the real issue.
What is a Noise Impact Assessment?
An NIA evaluates how your scheme affects nearby receptors — and how existing noise sources affect your site. Local Planning Authorities (LPA) and Environmental Health Officers (EHO) frequently require an NIA before granting approval or discharging planning conditions.
What the council is really asking for
When a planner or EHO requests BS4142 or BS8233, they are asking for:
A competent assessment route (correct standard, correct receptors, correct interpretation).
Evidence-quality measurements that represent the site and the relevant operating conditions.
Clear predictions of proposed noise impact at the nearest sensitive receptors.
Mitigation that is specific (not generic) and demonstrably capable of achieving compliance.
A conclusion they can act on (wording that supports conditions, approval, and discharge).
When you’ll need an NIA
Residential developments (demonstrate BS8233 internal noise criteria and appropriate external amenity guidance).
Industrial/commercial sites (plant, HVAC, extractor fans, deliveries and service yards assessed under BS4142 where applicable).
Transport exposure (road, rail, aircraft) for new buildings or material change of use.
Mixed-use schemes combining housing with retail/leisure.
For major schemes, the NIA may form part of an Environmental Impact Assessment (EIA).
Which standard applies to your project?
BS8233 — typically used for residential/internal criteria and external amenity guidance for new dwellings.
BS4142 — typically used for industrial/commercial sound: fixed plant, HVAC, extractor fans, deliveries, loading bays, service yards and operational features.
NPSE & NPPF — national policy context supporting planning decisions.
Planning Practice Guidance – Noise — planning interpretation and context.
If your project includes multiple sources (e.g., plant + transport), we set out a combined approach that keeps the submission clear and auditable.
Beyond the report: compliance-first plant selection and engineering design
Many noise reports identify a problem but don’t provide a practical engineering route to compliance. Because we are mechanical engineers as well as noise and vibration engineers, we can engineer the outcome — often by selecting the right equipment and installation strategy from the outset.
Specifying low-noise plant compatible with the duty (flow, pressure, duty cycle, controls) — not just “the quietest brochure figure”.
Managing structure-borne transmission (mounting, supports, duct breakout, vibration isolation).
Designing mitigation that is buildable and maintainable (enclosures, attenuators/silencers, discharge direction, screening, layout optimisation).
Reducing rework by aligning assessment, specification and mitigation into one coherent compliance route.
What our noise impact assessment report includes
Scope definition aligned to the planning ask: receptors, operating cases, measurement strategy, and applicable standard(s).
Baseline monitoring using precision sound level meters.
Prediction of operational and (where required) construction noise using accepted calculation and modelling methods.
Assessment against BS4142, BS8233, NPSE, and NPPF as applicable.
Practical mitigation: acoustic glazing, barriers/bunds, layout optimisation, operational limits, attenuated ventilation, low-noise plant specification, and (where appropriate) engineering refinements at source.
Stakeholder liaison: we engage early with councils and (where relevant) the Environment Agency to agree scope and avoid rework.
What you receive
Clear description of the proposal, site context, receptors and constraints.
Methodology, measurement locations, results tables and interpretation.
Predictions/modelling outputs and assessment tables aligned to the chosen standard(s).
Mitigation options and our recommended package (with performance intent and specification direction).
Conclusions written to support planning conditions and discharge where applicable.
If predicted noise is too high
Low-noise plant specification and acoustic enclosures.
Barriers/bunds, screening, and source–receiver re-layout.
Enhanced façades: acoustic glazing and attenuated ventilation.
Operational controls and timing restrictions.
Example outcome: BS4142 noise assessment for an air source heat pump (ASHP)
Initial MCS020 application was refused for exceeding permissible sound limits.
We completed baseline monitoring (Rion NL-53) and prepared a BS4142 report.
Result: ASHP was 6 dB below background at the nearest receptor (assessed case).
Outcome: the submission proceeded and approval was secured (timescale dependent on determination).
Recent example: extractor fan installation progressing via BS4142 route
A customer was instructed to provide a noise assessment before an application could proceed for an extractor fan installation close to residential receptors.
Our scope covered the BS4142 assessment and mitigation — but crucially, we also supported the project by sourcing and specifying compatible low-noise extraction units for the duty, so the proposal was engineered towards compliance from the outset.
Assessment route: BS4142 with a clear receptor basis and operating case definition.
Engineering outcome: compliant plant selection + practical mitigation package.
Commercial outcome: reduced risk of redesign, re-submission, and delay.
Why choose Environmentally Sound
Led by Chartered engineers with deep experience across acoustics, vibration, and mechanical design.
Not “report-only”: we can combine assessment with engineering specification and mitigation design to reach compliance faster.
A flexible consultancy model — we assemble the right specialists for each project, ensuring the exact expertise you need without unnecessary overheads.
Independent and insured consultancy for robust, impartial reporting.
Cost and timescale
Key standards & guidance
Contact
If you’ve been instructed to provide a BS4142 / BS8233 assessment, we’ll scope the work quickly, explain the compliance route, and deliver a robust Noise Impact Assessment that supports approval.
Contact Environmentally Sound
Written by Chartered engineers at Environmentally Sound Limited.
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