What This Requirement Covers
A noise impact assessment evaluates the external noise environment at a proposed development site and determines whether the noise levels are acceptable for the intended use. It is typically required as a planning condition for residential developments near roads, railways, airports, or commercial/industrial premises.
Key Requirements
When Required
- Residential developments near major roads (typically within 50-100 metres)
- Developments near railways or tram lines
- Developments within airport noise contours
- Developments near existing commercial or industrial premises
- Mixed-use developments where residential and commercial uses are adjacent
- Developments under Class MA permitted development (office to residential) where noise is a prior approval matter
Assessment Standards
- BS 8233:2014 (Guidance on sound insulation and noise reduction for buildings) sets internal noise criteria
- ProPG (Professional Practice Guidance on Planning and Noise): Provides a risk-based approach for assessing noise at residential developments
- WHO Guidelines: The World Health Organisation recommends night-time noise levels below 30 dB LAeq in bedrooms
Internal Noise Targets (BS 8233)
- Bedrooms (night): 30 dB LAeq,8h and 45 dB LAmax
- Living rooms (day): 35 dB LAeq,16h
- These are internal noise levels; the facade sound insulation must reduce external noise to meet these targets
Mitigation Measures
- Enhanced glazing specification (higher Rw rating)
- Non-openable windows with mechanical ventilation (MVHR)
- Acoustic vents instead of standard trickle vents
- Building orientation to place noise-sensitive rooms away from the noise source
- Acoustic fencing or barriers on the site boundary
Practical Compliance Tips
- Commission a noise survey early in the design process; it determines the glazing specification and ventilation strategy
- The noise survey must cover a representative 24-hour period (minimum) including daytime and night-time measurements
- Specify acoustic trickle vents where standard vents would not achieve adequate sound reduction
- Consider the interaction between noise and overheating; sealed windows for noise may conflict with Part O purge ventilation requirements
- MVHR with sound-attenuating ductwork provides both ventilation and noise mitigation for sealed facades
- The planning authority may require post-completion noise testing to verify compliance with the approved assessment
- Keep the noise assessment, glazing specifications, and testing results for the building file