Where relevant methodology or good practice exists for assessing a specific noise and its impact, it should followed when conducting and submitting a noise impact assessment.
Some developments and noise sources will fall outside of the scope of the published noise assessment methodologies. Some of these may be covered by examples of good practice so these should be used where appropriate.
These situations may also necessitate the use of parts, or a combination of, published assessment criteria. This allows for a bespoke assessment methodology to measure and assess the noise.
Irrespective of how a methodology is put together, the impact of the noise in question must be fully understood.
In these cases, it's important to consult the Environmental Health (Environmental Quality) Team early. The assessment methods and criteria should be agreed upon before the noise survey starts. Agreement should be make on how long the survey will last, where it will take place and which metrics to report. This will help accurately assess and show the noise impact.
Assessment and design criteria
Noise exposure hierarchy
No effect
At the lowest extreme, when noise is not perceived to be present, there is 'no effect'.
No observed effect
As the noise exposure increases, it will cross to the ‘no observed effect’ level.
However, the noise has no adverse effect as long as it does not alter behaviour, attitude or other physiological responses in those exposed to it. There may also be adverse health impacts at this level.
For example, the WHO night-noise guidance 2009 identifies physiological impacts due to sleep disturbance as a consequence of noise. This is the case even where the noise is not sufficient to trigger conscious awakening events.
The noise may slightly affect the acoustic character of an area but not to the extent there is a change in quality of life. If the noise exposure is at this level, no specific measures are required to manage the acoustic environment.
Lowest observed adverse effect
As exposure rises, it goes past the 'lowest observed adverse effect' boundary. At this point, noise begins to cause small changes in behaviour and attitude. For example, people might turn up the TV volume or speak louder to be heard.
Adverse effect
Consequently, the noise begins to have an 'adverse effect'. Consideration must be given to mitigating and minimising those effects. However, the economic and social benefits being derived from the noise causing activity must also be considered.
Significant observed adverse effect
Increasing noise exposure will at some point cause the ‘significant observed adverse effect’ boundary to be crossed.
Above this level the noise causes a material change in behaviour. For example, keeping windows closed for most of the time or avoiding certain activities during periods when the noise is present.
If the exposure is predicted to be above this level, the planning process should be used to avoid this effect occurring. For example, through the choice of sites at the plan-making stage or by use of appropriate mitigation such as by altering the design and layout.
Such decisions must be made taking into account the economic and social benefit of the activity causing or affected by the noise. However, it is undesirable for such exposure to be caused.
At the greatest extreme, noise exposure would cause extensive and sustained adverse changes in behaviour and/or health, without the ability to mitigate effects of the noise. The impacts on health and quality of life are such that regardless of the benefits of the activity causing the noise, this situation should be avoided.
Table 1 - Noise exposure hierarchy table
| Effect level | Response | Examples of outcomes | Increasing effect level | Action |
|---|---|---|---|---|
| No observed effect level | Not present | No Effect | No Observed Effect | No specific measures |
| No observed adverse effect level | Present and not intrusive | Noise can be heard, but does not cause any change in behaviour, attitude, or other physiological response. Can slightly affect the acoustic character of the area but not such that there is a change in the quality of life. | No Observed Adverse Effect | No specific measures required |
| Lowest observed adverse effect level | Present and intrusive | Noise can be heard and causes small changes in behaviour, attitude or other physiological response, e.g. turning up volume of television; speaking more loudly; where there is no alternative ventilation, having to close windows for some of the time because of the noise. Potential for some reported sleep disturbance. Affects the acoustic character of the area such that there is a small actual or perceived change in the quality of life. | Observed Adverse Effect | Mitigate and reduce to a minimum |
| Significant observed adverse effect level | Present and disruptive | The noise causes a material change in behaviour, attitude, or other physiological response, e.g. avoiding certain activities during periods of intrusion; where there is no alternative ventilation, having to keep windows closed most of the time because of the noise. Potential for sleep disturbance resulting in difficulty in getting to sleep, premature awakening, and difficulty in getting back to sleep. Quality of life diminished due to change in acoustic character of the area. | Significant Observed Adverse Effect | Avoid |
| Significant observed adverse effect level | Present and very disruptive | Extensive and regular changes in behaviour, attitude or other physiological response and/or an inability to mitigate effect of noise leading to psychological stress, e.g. regular sleep deprivation/awakening; loss of appetite, significant, medically definable harm, e.g. auditory and non-auditory | Unacceptable Adverse Effect | Prevent |
New residential
British Standard 8233:2014 and ProPG: Planning and Noise 2017 sets the internal target noise criteria for residential premises exposed to external noise sources. These will often be anonymous in nature such as transport noise sources. These criteria are summarised in Table 2 below. A BS8233 noise impact assessment can be used to determine noise reduction and sound insulations requirements for buildings.
Table 2 - Indoor ambient noise level limits for dwellings
| Activity | Location | 7am to 11pm | 11pm to 7am |
|---|---|---|---|
| Resting | Living room | 35 dB LAeq,16 hr | - |
| Dining | Dining room / area | 40 dB LAeq,16 hr | - |
| Sleeping (daytime resting) | Bedroom | 35 dB LAeq,16 hr | 30 dB LAeq, 8 hr and not exceeding 45 dB LAmax, F more than 10 times |
At the time of writing this noise guidance note in early 2025, it is known that BS 8233 is currently under development. The draft is expected to be published for public consultation imminently. The proposed changes to BS 8233 will include significant new guidance on noise impact assessment for new residential developments.
Therefore, any new development needs to be assessed in accordance with the version in effect at the time.
There is no good reason development in appropriate locations should not be able to achieve these criteria, provided appropriate acoustic design is implemented.
This can be achieved through site layout, incorporating good acoustic design principles. Allow criteria to be met with windows open, and where practicable, using passive ventilation solutions such as:
- building orientation
- room orientation
- acoustic/plenum windows
- acoustic balconies
- façade treatments
Site layout and room orientation should be the first consideration in achieving internal noise levels. Only when site layout solutions have been exhausted, should façade solutions be considered. Table B5 of the Acoustics, Ventilation and Overheating (AVO) Guide 2020 provides information on passive solutions providing noise attenuation.
The Building Regulations 2010 Approved Document O (Overheating) favours passive ventilation wherever possible. Sealed facades with active cooling measures may be acceptable in locations acoustic criteria otherwise cannot be achieved.
Where the internal noise levels shown in Table 2 cannot be achieved with windows open, good acoustic design and passive design measures should be used to minimise internal noise levels as far as practicable. Supplementary mechanical ventilation, such as a mechanical heat recovery system (with cool air bypass) systems, should also be provided. These must be in accordance with Part F (ventilation) and Part O (overheating) of The Building Regulations 2010. Any supplementary mechanical ventilation must:
- Provide mechanical supply ventilation, to allow for occupants to have adequate levels of fresh air, should they choose to shut windows to screen out noise. In instances where this is likely, applicants will need to provide a report from a ventilation specialist which follows the guidance in the Chartered Institute of Building Engineers (CIBSE) Environmental Design Guide 2021, or later replacement guidance.
- Not compromise the façade insulation or the resulting internal noise level.
Any design measures that are used to control the ingress of noise must be consistent and compatible with the requirements of the Building Regulations. External noise assessment criteria
British Standard 4142 is the governing guidance where noise of an industrial or commercial nature is under consideration. This method is to be used for assessing
impact from noise sources within the scope of this methodology. Please refer to BS 4142:2014+A1:2019 (or as updated), for further information. Where BS 4142 assessments are carried out, the council’s advice is detailed below.
New noise sensitive development near existing industrial or commercial sources
Generally, for new noise sensitive development the concern is internal noise levels (except for external amenity areas). However, if external noise levels are high, it is likely that there will be need for alternative ventilation. Use of active ventilation to mitigate should be a last resort with implement Good Acoustic Design principles from the outset.
External amenity space
An External Amenity Area Noise Assessment should be carried out in accordance with the guidance in ProPG. This is to demonstrate good acoustic design and make sure that noise levels will not exceed the range of 50 – 55 dB LAeq, 16hr within external amenity spaces as far as practicable. This includes areas such as gardens, patios, larger balconies, roof gardens and terraces.
In higher noise areas, such as town centres or urban areas adjoining the strategic transport network, a compromise between elevated noise levels and other factors, such as the convenience of living in these locations or making efficient use of land to ensure development needs can be met, might be warranted.
The decision to exercise this discretion will be determined by:
- the degree to which mitigation is proposed
- the proportion of the development affected
- the profile of noise over a 16hr period
This relaxation is not to be applied ahead of mitigation schemes which would provide the desired level of protection.
Some developments, such as flats and apartment blocks may be built with small balconies or terraces. Where this is the case and provision has been made for outdoor amenity space elsewhere in the development, such as roof gardens or in grounds surrounding the development, the external design criteria will not be applied to the small balcony or terrace.
New noise sources
Noise from new mechanical sources should be no higher than the existing background noise level assessed in accordance with BS 4142:2014+A1:2019.
Plant noise should be assessed in accordance with BS 4142:2014+A1:2019. Plant selection, orientation, layout, and mitigation should make sure that the noise rating level is no higher than the existing background noise level. Noise limits and mitigation, such as acoustic barrier or enclosure provision and specifications, and maintenance of mitigation may be conditioned as part of consent.
Deliveries
Where any new retail, commercial or industrial premises are proposed, numbers and hours of deliveries are often a relevant noise consideration. Where delivery and associated activities (such as use of fork-lift trucks) is likely to be regular and significant (as with supermarkets and warehouses) a noise assessment will be required.
Noise associated with deliveries, such as manoeuvring vehicles, engines, unloading, loading and reverse alarms, should be assessed in accordance with BS 4142:2014+A1:2019. Delivery hours and mitigation should make sure the noise rating level is no higher than the existing background noise level. Noise limits, hours and mitigation (acoustic barrier) and maintenance of mitigation may be conditioned as part of consent.
Proposed licensed premises – amplified music, etc
Planning and licensing are separate legal frameworks. There is some overlap, particularly with noise nuisance. Both planning and licensing authorities must check how proposals might impact the local community during development.
At the planning stage, provide structural design details for consideration. Include orientation, layout, sound insulation, kitchen extraction and air handling plant. This should be supported by a noise assessment.
There may be scenarios where applications/operators may also be required by planning condition to submit a noise management plan.
Softer operational controls, such as keeping doors and windows closed, using signage or setting music times, are usually handled under the Licensing Act 2003, not planning.
Domestic air source heat pumps
The installation of a single air source heat pump on domestic premises is usually considered to be permitted development, provided that certain conditions are met.
These conditions have been set to make sure that any negative impacts such as appearance, siting and noise are kept to a minimum. More information about when an air source heat pump does not require planning permission can be found on the council’s website.
The Microgeneration Certification Scheme (MCS020) sets a permitted development noise limit of 42dB at all sensitive receptors. Generally, all domestic heat pumps (permitted development and those not meeting permitted development) should aim to achieve this limit, which can be demonstrated by calculation.
For installations which do not meet the noise limit, it is not permitted development and a full application is required to be submitted.
Applicants should consider their options for their proposed ASHP in order to meet the 42dB limit so Environmental Health can recommend it to Planning for approval. Potential options could include:
- quieter alternative heat pump models
- relocation
- reorientation
- enhanced boundary treatment (solid wall close-boarded fence)
- acoustic enclosure
For installations which, after attempts to reduce the noise level to meet the MCS020 limit, are still over the 42dB limit, the application would be recommended for refusal.