Purpose
The noise impact assessment checks if the proposed development will be affected by noise. It also looks at whether it will create noise that impacts nearby developments.
This will inform the decision-making process for proposed development but should be used as a tool during the design stage. If a noise impact assessment highlights noise as an issue, mitigation will need to be considered.
The design of a proposal will often be crucial to effective mitigation. It is often possible to mitigate the predicted noise impact. Where the mitigation is demonstrated to be sufficient, concerns regarding noise can be alleviated.
When a noise impact assessment is required
The developer or applicant should consider if a proposal is likely to cause a noise impact or be adversely affected by noise. If considered likely, they should carry out a noise impact assessment for their proposed development.
Advice can be sought from the Environmental Health Team at the council. They will talk about the proposed development and look for noise concerns. These might be issues the developer knows about or ones the council finds.
Where noise is likely to be a constraint or a consideration in the decision-making process for a planning application, it is expected that a noise impact assessment will be submitted to accompany that planning application. Where this is the case, often the design of a scheme or a proposal could offer the solution.
Where a noise impact assessment is necessary and is not submitted, Environmental Health will object to the proposal in its consultation response.
For situations when a noise impact assessment will be required to support a planning application, refer to:
- Appendix 2 - regarding new noise sensitive development
- Appendix 3 - regarding new noise sources
Scope, content and competency
A Noise Impact Assessment submitted in support of proposed development must:
- demonstrate that noise sources are fully understood and quantified
- that all nearby noise sensitive receptors have been identified
- that the impact on the receptor has been established, with reference to relevant acceptability criteria
- set out specific mitigation measures to demonstrate good acoustic design and compliance with relevant criteria, guideline, or standard values
As noise is a specialist area of work, where developers are required to submit a noise assessment, it must be carried out by a competent person.
To be considered competent, consultants must hold qualifications on the assessment of environmental noise and/or building acoustics. They should also be members of the Institute of Acoustics.
Acoustic consultancies should be members of the Association of Noise Consultants.
The council may also ask for a post-completion noise assessment to demonstrate that the finished development (with mitigation) achieves the criteria. Most acceptability criteria are set out in British Standards or other published guidance (see below).
In some cases, if there’s no published guidance, you'll need to agree on the methodology and criteria with the Environmental Health team before starting the work.
If a developer engages someone who is not appropriately qualified or a member of the above organisations, the Environmental Health Team will not accept the work as competent and will advise the LPA.
The report submitted should be set out in a format which is logical and understandable. It should provide the council with the information it requires about the:
- consultant
- instrumentation used
- methodology
- relevant criteria
- survey undertaken
- noise sources
- receptors
- the judged impact
- mitigation proposed
See Appendix 4 for the expected noise measurement survey and report format.
Assessing and determining the impact of noise
The purpose of a noise assessment is to understand the impact of a noise source on a receptor and specify any necessary mitigation measures.
National planning policy and guidance (NPPF 2024, Planning Practice Guidance – Noise 2019 and the Noise Policy Statement for England 2010) does not set out specific noise level criteria for assessing the impact of noise. Reliance is placed on other published guidance (see Appendix 5), to judge the significance of noise for any proposed scheme.
Transportation and environmental noise
For proposed development, where existing or new transport noise is relevant, proposals will be tested against the noise acceptability criteria detailed in the ProPG: Planning & Noise - Professional Practice and Guidance on Planning & Noise 2017. This places a clear emphasis on encouraging good acoustic design for new residential development to protect residents from the harmful effects of noise.
This guidance focuses on new homes near transport noise. However, the basic ideas of good acoustic design should also apply to other similar noise sources.
ProPG recommends a 2-stage approach. an initial noise risk assessment of the proposed development site. And, where the results indicate that noise requires further consideration, a full assessment in the form of an Acoustic Design Statement. A noise impact assessment will inform how risk from noise is assessed and what is set out in an Acoustic Design Statement.
The main emphasis of ProPG is the encouragement of good acoustic design at an early stage of the development process. Good acoustic design considers site layout, building massing, orientation and internal layout.
For medium to high risk noise sites, it is imperative that the following are considered at the outset of the design:
- building location
- design
- orientation
- room layout
- use of buildings as noise shields
Consideration of acoustic design after the site and building layout has been defined, will not be considered good acoustic design. The ProPG details:
In requiring good acoustic design, there is a hierarchy of noise management measures that LPAs should encourage, including the following, in descending order of preference:
- Maximising the spatial separation of noise source(s) and receptor(s).
- Investigating the necessity and feasibility of reducing existing noise levels and relocating existing noise sources.
- Using existing topography and existing structures (that are likely to last the expected life of the noise-sensitive scheme) to screen the proposed development site from significant sources of noise.
- Incorporating noise barriers as part of the scheme to screen the proposed development site from significant sources of noise.
- Using the layout of the scheme to reduce noise propagation across the site.
- Using the orientation of buildings to reduce the noise exposure of noise- sensitive rooms.
- Using the building envelope to mitigate noise to acceptable levels.
It should be remembered that good acoustic design is a process that begins as soon as land is under consideration for development. The timeline for good acoustic design stretches from the conceptual design stage, through quality control during construction, and beyond to post construction performance testing.
Both internal and external spaces should be considered in the acoustic design process. Care should be taken to ensure that acoustic mitigation measures do not result in an otherwise unsatisfactory development. Good acoustic design must be regarded as an integrated part of the overall design process.
Refer to ‘ProPG: Planning & Noise Supplementary Document 2 – Good Acoustic Design’ for further information.
Good acoustic design will make sure that internal noise levels can be achieved with windows open as far as reasonably practicable. At the same time, it will mitigate the impact of noise on external amenity areas such as gardens.
Closing windows to meet acoustic standards isn’t ideal. Open windows allow for passive ventilation. This is the preferred and most energy-efficient approach to mitigate overheating. The Acoustics, Ventilation and Overheating Residential Design Guide (2019, IOA & ANC) and in Approved Document O (2021) establishes a hierarchy of approaches to mitigating overheating. These may include active ventilation and cooling where internal acoustic standards cannot be met with open windows.
Noise generating developments
For proposed development where commercial or industrial noise is proposed, an assessment using BS 4142:2014+A1:2019 will be required. This is the standard method for rating and assessing industrial and commercial sound.
As per published national planning policy and in accordance with Policy LP58 ‘Pollution and hazards’ of the BFLP, development should:
- minimise and reduce pollution and hazards
- mitigate any adverse impacts
- provide improvements where possible
Policy LP58 requires consideration of both individual and cumulative effects. Both when completed and during construction. It seeks to avoid locating sensitive uses in areas with existing pollution or hazards, and/or to avoid locating them in areas likely to have them in future.
Developers are expected to adhere to the following guiding principles:
- Development should not give rise to, or be exposed to noise, which would have any adverse impact on human health, wellbeing, safety, and residential amenity. Where possible, development should contribute to the improvement of quality of life. A precautionary approach should be taken to make sure they will not be subject to harm.
- Development proposals should not have an adverse impact on the natural environment. Care should be taken near to sites protected for their biodiversity or in ecologically sensitive areas.
- It may not always be possible to achieve ‘i)’ or ‘ii)’due to land use pressures and the development of land in urban environments, where environmental noise often cannot be avoided. Where a noise source is to be introduced, or a new development is to be exposed to an existing noise source, exposure to the noise in question must be mitigated and minimised. This is to avoid any adverse impacts.
There will be occasions where existing noise or noise from proposed development is inevitable and any proposed mitigation will have limited benefit. However, the development in question may be viewed as favourable for a variety of other reasons.
In this situation, where all mitigation options have been explored and noise is to be mitigated as far as reasonably practicable, noise should not give rise to any significant adverse impacts. This is a as a minimum standard. Developments which are considered to have significant adverse impacts will not be supported.
New noise sensitive receptors
Outline planning applications for new residential developments at sites considered to pose a medium or high noise risk must demonstrate that good acoustic design will overcome the acoustic challenges present at the development site.
Acoustically critical issues should not be left for agreement at the later ‘Reserved Matters’ stage.
Acoustically critical issues might involve:
- site layout
- building heights
- materials
- landform contouring
- detailed design and landscaping
- location of vehicle and pedestrian access
- boundary treatments
- amenity spaces
Any changes in acoustically critical issues following grant of outline consent should be fully assessed in an Acoustic Design Statement.
Where proposals do not follow these principles, Environmental Health are likely to raise an objection.
Agent of change
The agent of change principle came in the 2018 NPPF. This made the party introducing a new land use or development (considered the "agent of change”) responsible for mitigating any negative impacts on existing neighbouring uses.
If a new development is built near an established business that generates noise, the new development must take steps to manage that noise. The existing business will not have to change its operations due to the new residents.
In these circumstances, the applicant (or 'agent of change') must identify how existing businesses might cause a nuisance. This could mean looking at noise, dust, odours, vibration, or other pollution sources. They must determine how likely it is that these will have a significant negative impact on new residents or users.
The agent of change must understand the current activities causing a nuisance. They also need to know what activities businesses or facilities are permitted to carry out, even if those activities are not occurring at the time of application.
The agent of change must define the proposed mitigation to address any potential significant adverse effects that are identified.
Prospective purchasers or occupants should be informed of noise mitigation measures in use. For example, keeping windows closed and using alternative ventilation systems. This is to raise awareness and reduce the risk of post-purchase or occupancy complaints.
The 'agent of change' principle works both ways. If a new venue or noise generating development is built near to an existing residential development, the onus will be on the new development to put noise mitigating measures in place.