14. The selection of a site, the design of a development and the conditions which may be attached to a planning permission can all play a part in preventing, controlling and mitigating the effects of noise. Discussions with the planning authority prior to submitting an application will assist in deciding the level of detail required from an applicant in respect of noise. The level of detail required should be balanced against the degree of risk to environmental quality, public health and amenity. More detailed assessments may be required for proposals that are likely to generate significant noise; for noise sensitive proposals which may affect existing noise sources and for proposals that may affect noise levels within or close to NMAs or Quiet Areas.
15. Issues which may be relevant when considering noise in relation to a development proposal include:
- Type of development and likelihood of significant noise impact,
- Sensitivity of location ( e.g. existing land uses, NMA, Quiet Area),
- Existing noise level and likely change in noise levels,
- Character (tonal, impulsivity etc), duration, frequency of any repetition and time of day of noise that is likely to be generated, and
- Absolute level and possible dose-response relationships 2 e.g. health effects if robust data available.
16. It is preferable that satisfactory noise levels can be achieved within dwellings with the windows sufficiently open for ventilation. Local circumstances, particularly relating to the existing noise character of the area, should influence the approach taken to noise levels with open or closed windows. It may be appropriate to take a different approach to noise levels in different areas. It may also be appropriate to take a different approach to noise levels when considering the effects of new noisy development on existing residential properties from the approach taken to new residential development close to existing noisy land uses. Satisfactory internal noise levels with open windows may not always be achievable, but are always preferable. Where satisfactory levels with open windows are not achievable, practicable mitigation solutions should be explored, taking into account their possible impact on the built environment. Design solutions may be possible, such as locating living rooms and bedrooms on the opposite side of a building to the source of the noise or use of windows designed to provide for ventilation while providing improved sound reduction. In some circumstances however, closed windows with alternative means of ventilation may be unavoidable. Passive systems may be considered but mechanical ventilation should only be used as a last resort. Sound levels in gardens and amenity areas may also need to be considered in terms of enabling a reasonable degree of peaceful enjoyment of these spaces for residents.
17. Planning authorities should refer to Noise Action Plans when determining applications for development which may affect a Quiet Area or Noise Management Area. Development proposals which are likely to generate significant noise impacts may need to be advertised as Schedule 3 Development under Regulations 20(1)(c) and 38(1)(b) of the Town and Country Planning (Development Management Procedure) (Scotland) Regulations 2008.
18. When considering applications for new noise sensitive development close to an existing noise source, the likely level of noise exposure at the time of the application and any increase that may reasonably be expected in the foreseeable future are likely to be relevant, as will the extent to which it is possible to mitigate the adverse effects of noise.
Noise Impact Assessment
19. The preparation and consideration of planning applications that raise significant noise issues can be greatly assisted by a Noise Impact Assessment ( NIA). Planning authorities can require a NIA either as part of an Environmental Impact Assessment or separately. The need for noise impact assessments is best identified during pre-application discussions. The purpose of a NIA is to demonstrate whether any significant adverse noise impacts are likely to occur and if so, identify what effective measures could reduce, control and mitigate the noise impact. Before a NIA is commissioned, planning authorities and applicants are advised to:
- Agree any potential representative limits of noise and /or the relevant NIA methodology in the context of the proposed development, its location and the surrounding area, and
- Establish criteria for assessing any significant adverse noise impact or predict and describe ambient noise levels (including noise from transport sources) that the proposed development is likely to generate and/or is likely to be subjected to.
For further information on NIA methodologies see the Technical Advice Note.