wretwick green appendix 12.2
TRANSCRIPT
Appendix 12.2
Introduction12.2
12.2.1 This appendix presents the assessment criteria and significance used in Environmental StatementChapter 12 Noise and Vibration. The relevant legislation, policy and various guidance documents arelisted herein.
12.2.2 Explanations are provided in relation to the use of the various documents in order to define theassessment thresholds in relation to planning policy and, where applicable, the magnitude of impactwhich is the first criterion in the process required to define significance under the EnvironmentalImpact Assessment Directive
1. Guidance documents may be repeated in different sections of this
document since these can be used to define the assessment target levels for construction andoperation.
Legislation12.3
The Control of Pollution Act 1974
12.3.1 The Control of Pollution Act 19742, Section 61 sets out procedures for contractors to obtain ‘Prior
Consent’ for construction works within agreed noise limits.
12.3.2 Prior to the start of construction work, there would be an assessment of construction noise impactstaking account of the methods of working to be employed. Applications for prior consent would bemade to the local authority. These would contain a method statement of the proposed works and thesteps that would be taken to minimise and mitigate noise to acceptable levels and time periods duringthe whole construction period.
The Environmental Protection Act
12.3.3 Under Part III of the Environmental Protection Act 19903, local authorities have a duty to investigate
noise complaints from premises (land and buildings) and vehicles, machinery or equipment in thestreet. This includes noise arising from construction sites.
12.3.4 If a Local Authority's Environmental Health Officer (EHO) is satisfied that the problem complainedabout amounts to a statutory nuisance then the authority must serve an abatement notice on theperson responsible or in certain cases the owner or occupier of the property. The notice could requirethat the noise or nuisance must be stopped altogether or limited to certain times of the day.
National Policy12.4
Noise Policy Statement for England4
12.4.1 The Noise Policy Statement for England (NPSE5), published in March 2010, sets out the long-term
vision of Government noise policy. The Noise Policy aims, as presented in this document, are:
“Through the effective management and control of environmental, neighbour and neighbourhoodnoise within the context of Government policy on sustainable development:
avoid significant adverse effects on health and quality of life;
mitigate and minimise adverse effects on health and quality of life; and
where possible, contribute to the improvement of health and quality of life.”
1The EIA Directive (85/337/EEC) in force since 1985
2http://www.legislation.gov.uk/ukpga/1974/40
3 http://www.legislation.gov.uk/ukpga/1990/43/part/III4 https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69533/pb13750-noise-policy.pdf5 Noise Policy Statement for England, Defra, March 2010
12.4.2 The NPSE makes reference to the concepts of NOEL (No Observed Effect Level) and LOAEL(Lowest Observed Adverse Effect Level) as used in toxicology but applied to noise impacts. It alsointroduces the concept of SOAEL (Significant Observed Adverse Effect Level) which is described asthe level above which significant adverse effects on health and quality of life occur.
12.4.3 The first aim of the NPSE is to avoid significant adverse effects, taking into account the guidingprinciples of sustainable development (as referenced in Section 1.8 of the NPSE). The second aimseeks to provide guidance on the situation that exists when the potential noise impact falls betweenthe LOAEL and the SOAEL, in which case: “…all reasonable steps should be taken to mitigate andminimise adverse effects on health and quality of life while also taking into account the guidingprinciples of sustainable development.” Importantly, the NPSE goes on to state: “This does not meanthat such adverse effects cannot occur.”
12.4.4 The NPSE does not provide a noise-based measure to define SOAEL, acknowledging that theSOAEL is likely to vary depending on the noise source, the receptor and the time in question. NPSEadvises that: “Not having specific SOAEL values in the NPSE provides the necessary policy flexibilityuntil further evidence and suitable guidance is available.”
12.4.5 It is therefore likely that other guidance will need to be referenced when applying objective standardsfor the assessment of noise, particularly in reference to the SOAEL, whilst also taking into accountthe specific circumstances of a proposed development.
National Planning Policy Framework
12.4.6 The National Planning Policy Framework (NPPF6) was published in March 2012. One of the
documents that the NPPF replaced was Planning Policy Guidance Note 24 (PPG 247) “Planning and
Noise.”
12.4.7 Paragraph 109 of the NPPF states that the planning system should contribute to and enhance thenatural and local environment by, (amongst others):
“preventing both new and existing development from contributing to or being put at unacceptablerisk from, or being adversely affected by unacceptable levels of soil, water or noise pollution orland stability.”
12.4.8 The NPPF goes on to state in Paragraph 123 “planning policies and decisions should aim to:
Avoid noise from giving rise to significant adverse impacts on health and quality of life as a
result of new development;
Mitigate and reduce to a minimum other adverse impacts on health and quality of life arising
from noise from new development, including thorough use of conditions;
Recognise that development will often create some noise and existing businesses wanting to
develop in continuance of their business should not have unreasonable restrictions put on them
because of changes in nearby land use since they were established, and
Identify and protect areas of tranquility which have remained relatively undisturbed by noise and
are prized for their recreational and amenity value.”
12.4.9 The NPPF document does not refer to any other documents regarding noise other than the NPSE.
12.4.10 Paragraph 11 of the NPPF states that “planning law requires that applications for planning permissionmust be determined in accordance with the development plan unless material considerations indicateotherwise.”
12.4.11 Paragraph 13 of the NPPF states that “the National Planning Policy Framework constitutes guidancefor local planning authorities and decision-takers both in drawing up plans and as a materialconsideration in determining applications.”
12.4.12 Therefore, if a development/local plan does not align closely with the NPPF, planning decisionsshould be based on assessments which align with the NPPF. So for instance if a development isrefused permission due to conflicts with the local plan, this decision can be overturned (i.e. via theappeal process) if the local plan did not closely align with the aims in the NPPF.
12.4.13 Paragraph 17 of the NPPF states that one of the 12 principles of planning is that it should “not simplybe about scrutiny, but instead be a creative exercise in finding ways to enhance and improve theplaces in which people live their lives.”
6 National Planning Policy Framework, DCLG, March 20127 Planning Policy Guidance 24: Planning and Noise, DCLG, September 1994
Planning Practice Guidance – Noise
12.4.14 As of March 2014, a Planning Practice Guidance (PPG8) for noise was issued which provides
additional guidance and elaboration on the NPPF. It advises that when plan-making and decision-taking, the Local Planning Authority should consider the acoustic environment in relation to:
Whether or not a significant adverse effect is occurring or likely to occur;
Whether or not an adverse effect is occurring or likely to occur; and
Whether or not a good standard of amenity can be achieved.
12.4.15 This guidance introduced the concepts of NOAEL (No Observed Adverse Effect Level), and UAEL(Unacceptable Adverse Effect Level). NOAEL differs from NOEL in that it represents a situationwhere the acoustic character of an area can be slightly affected (but not such that there is aperceived change in the quality of life). UAEL represents a situation where noise is ‘noticeable’, ‘verydisruptive’ and should be ‘prevented’ (as opposed to SOAEL, which represents a situation wherenoise is ‘noticeable’ and ‘disruptive’, and should be ‘avoided’).
12.4.16 As exposure increases above the LOAEL, the noise begins to have an adverse effect andconsideration needs to be given to mitigating and minimising those effects, taking account of theeconomic and social benefits being derived from the activity causing the noise. As the noiseexposure increases, it will then at some point cross the SOAEL boundary.
12.4.17 The LOAEL is described in PPG as the level above which “noise starts to cause small changes inbehaviour and/or attitude, e.g. turning up volume of television; speaking more loudly; where there isno 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 thatthere is a perceived change in the quality of life.”
12.4.18 PPG identifies the SOAEL as the level above which “noise causes a material change in behaviourand/or attitude, e.g. avoiding certain activities during periods of intrusion; where there is noalternative 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 anddifficulty in getting back to sleep. Quality of life diminished due to change in acoustic character of thearea.”
12.4.19 In line with the Explanatory Note of the NPSE, the PPG goes on to reference the LOAEL and SOAELin relation to noise impact. It also provides examples of outcomes that could be expected for a givenperception level of noise, plus actions that may be required to bring about a desired outcome.However, in line with the NPSE, no objective noise levels are provided for LOAEL or SOAELalthough the PPG acknowledges that: “…the subjective nature of noise means that there is not asimple relationship between noise levels and the impact on those affected. This will depend on howvarious factors combine in any particular situation.”
12.4.20 The relevant guidance in the PPG in relation to the adverse effect levels is summarized in the tablebelow:
8 Planning Practice Guidance – Noise, http://planningguidance.planningportal.gov.uk/blog/guidance/noise/, 06 March 2014
Table 12.2.1 Planning Practice Guidance categorization of effects
Perception Examples of Outcomes Increasing EffectLevel
Action
NotNoticeable
No Effect No Observed Effect No specificmeasuresrequired
Noticeableand
notIntrusive
Noise can be heard, but does not cause any change inbehaviour or attitude. Can slightly affect the acoustic characterof the area but not such that there is a perceived change in thequality of life.
No ObservedAdverse Effect
No specificmeasuresrequired
Lowest Observed Adverse Effect Level
Noticeableand
Intrusive
Noise can be heard and causes small changes in behaviourand/or attitude, e.g. turning up volume of television; speakingmore loudly; where there is no alternative ventilation, having toclose windows for some of the time because of the noise.Potential for some reported sleep disturbance. Affects theacoustic character of the area such that there is a perceivedchange in the quality of life.
Observed AdverseEffect
Mitigate andreduce to aminimum
Significant Observed Adverse Effect Level
Noticeableand
Disruptive
The noise causes a material change in behaviour and/orattitude, e.g. avoiding certain activities during periods ofintrusion; where there is no alternative ventilation, having tokeep windows closed most of the time because of the noise.Potential for sleep disturbance resulting in difficulty in getting tosleep, premature awakening and difficulty in getting back tosleep. Quality of life diminished due to change in acousticcharacter of the area.
Significant ObservedAdverse Effect
Avoid
Noticeableand veryDisruptive
Extensive and regular changes in behaviour and/or an inabilityto mitigate effect of noise leading to psychological stress orphysiological effects, e.g. regular sleep deprivation/awakening;loss of appetite, significant, medically definable harm, e.g.auditory and non-auditory
UnacceptableAdverse Effect
Prevent
12.4.21 The Planning Practice Guidance states the following in relation to mitigation measures:
“For noise sensitive developments mitigation measures can include avoiding noisy locations;designing the development to reduce the impact of noise from the local environment; includingnoise barriers; and, optimising the sound insulation provided by the building envelope. Careshould be taken when considering mitigation to ensure the envisaged measures do not make foran unsatisfactory development.”
12.4.22 The Planning Practice Guidance provides further advice as it states that:
“the noise impact may be partially off-set if the residents of those dwellings have access to:
a relatively quiet facade (containing windows to habitable rooms) as part of their dwelling,
and/or;
a relatively quiet external amenity space for their sole use, (e.g. a garden or balcony). Although
the existence of a garden or balcony is generally desirable, the intended benefits will be
reduced with increasing noise exposure and could be such that significant adverse effects
occur, and/or;
a relatively quiet, protected, nearby external amenity space for sole use by a limited group of
residents as part of the amenity of their dwellings, and/or;
a relatively quiet, protected, external publically accessible amenity space (e.g. a public park or a
local green space designated because of its tranquility) that is nearby (e.g. within a 5 minutes
walking distance).”
12.4.23 In addition the document also states that “consideration should also be given to whether adverseinternal effects can be completely removed by closing windows and, in the case of new residentialdevelopment, if the proposed mitigation relies on windows being kept closed most of the time. In bothcases a suitable alternative means of ventilation is likely to be necessary. Further information onventilation can be found in the Building Regulations”.
Technical Guidance/ Best Practice12.5
12.5.1 This section presents a summary of relevant guidance which is applied in noise/vibration impactassessments. Relevant information from this guidance is presented in subsequent sections asappropriate.
British Standard 8233: 2014 ‘Guidance on Sound Insulation and noise reduction for buildings
12.5.2 BS 8233 sets out desirable guideline values in habitable rooms such as living rooms and bedrooms.The standard also provides advice in relation to design criteria for external noise.
12.5.3 The guideline values relate to steady external noise without a specific character, previously termed‘anonymous noise’. According to the standard, noise has a specific character if it contains featuressuch as a distinguishable, discrete and continuous tone, is irregular enough to attract attention, orhas strong low-frequency content, in which case lower noise limits might be appropriate. Examples ofnoise with a character may include tonal/intermittent plant noise emissions, music playback, andworkshop noise. Examples of external steady noise sources may include environmental noisesources such as busy road traffic.
Calculation of Road Traffic Noise (CRTN): 19889
12.5.4 CRTN describes procedures for traffic noise calculation and is suitable for environmentalassessments of schemes where road traffic noise may have an impact. The ‘Method for convertingthe UK road traffic noise index LA10,18h to the EU indices for road noise mapping’
10can be used to
convert LA10,18h road traffic noise levels to LAeq,16h daytime and LAeq,8h night-time ambient noise levels.
Design Manual for Roads and Bridges
9 Volume 11, Section 3, Part 7. http://www.noiseni.co.uk/calculation_of_road_traffic_noise.pdf10 (TRL, Casella Stanger, 2006)
12.5.5 The Design Manual for Road and Bridges11
provides detailed guidance on noise and vibrationassessments for road schemes in the UK. DMRB gives guidance and interpretation on the magnitudeof noise impact from road traffic sources and it includes example semantic scales for classifying themagnitude of short term and long term impacts.
British Standard 5228:2009+A1:2014 Code of Practice for Noise and Vibration Control onConstruction and Open Sites
12.5.6 BS 5228 Part 1: Noise does not provide limits for construction noise. The standard, as a whole,provides practical information on demolition and construction noise and vibration reduction measures,and promotes a ‘Best Practice Means’ approach to control noise and vibration.
12.5.7 The calculation method provided in BS 5228 Part 1 is based on the numbers and types of equipmentoperating, their associated Sound Power Levels (Lw), and the distance to receptors, together with theeffects of any screening.
12.5.8 BS 5228 Part 2: Vibration provides similar guidance for vibration effects including vibration due topiling activities. Likely levels of vibration at given distances can be estimated from existing pilingvibration data and formulae presented in this British Standard.
British Standard 4142: 2014 ‘Methods for rating and assessing industrial and commercial sound”
12.5.9 British Standard 4142: 2014 is intended to be used to assess the noise impact from factories,industrial premises and sources of an industrial nature in commercial premises.
British Standard ‘6472 -1:2008 Guide to evaluation of human exposure to vibration in Buildings’
12.5.10 British Standard 6472 Part 1 is used to assess vibration levels experienced by people in buildingsfrom a human comfort perspective. BS 6472 provides guidance on methods of measuring andevaluating vibration in the frequency range 0.5 Hz to 80 Hz. The standard indicates that vibrationdose values (VDVs) can be used to assess the human exposure to vibration when the vibrations areof continuous, impulsive or intermittent type and assesses the magnitude and duration of vibration.
British Standard 7445-1:2003 Description and measurement of environmental noise. Guide toquantities and procedures
12.5.11 BS 7445-1 describes methods and procedures for measuring noise from all sources which contributeto the total noise climate of a community environment, individually and in combination. The resultsare expressed as equivalent continuous A-weighted sound pressure levels, LAeq,T.
World Health Organisation, Guidelines for Community Noise, 1999 (WHO)
12.5.12 The World Health Organisation (WHO) Guidelines for Community Noise (1999) also sets outguidance on suitable internal and external noise levels in and around residential properties.
World Health Organisation (WHO) 2009: Night Noise Guidelines for Europe
12.5.13 The introduction of the Directive on Environmental Noise, obliges Member States to assess andmanage noise levels. With the support of the European Commission, the WHO Regional Office forEurope has developed night noise guidelines for Europe to help Member States develop legislation tocontrol noise exposure.
12.5.14 The guidelines are based on scientific evidence on the effects of noise and the thresholds abovewhich these effects appear to harm human health.
11 http://www.standardsforhighways.co.uk/dmrb/vol11/section3/hd21311.pdf
12.5.15 The WHO report summarises the threshold levels of night noise above which a negative effect startsto occur or above which the impact becomes dependent on the level of exposure.
12.5.16 It also established that there are differences in the intensity and frequency of noise depending on thesource, which lead to different impacts. Road traffic is characterised by low levels of noise per event,but as there are a high number of events, on average it has a greater effect on awakenings than airtraffic, which has high levels of noise per event but fewer events.
Significance Criteria12.6
Introduction
12.6.1 This section describes the methodology to be used to undertake the assessment of noise andvibration impacts and effects associated with the proposed development.
Planning policy
12.6.2 In accordance with the National Planning Policy Framework (NPPF), Noise Policy Statement forEngland (NPSE) and Planning Practice Guidance (PPG), lowest observable adverse effect level(LOAEL) and significant observable adverse effect levels (SOAEL) are proposed for each noise andvibration source under assessment in this Environmental Statement Chapter.
12.6.3 In accordance with national policy and guidance no mitigation measures are required below theLOAEL, levels above the SOAEL should be avoided (however, these could be acceptable in theplanning balance) and levels between the LOAEL and SOAEL should be reduced using reasonablypracticable mitigation measures.
EIA Regulations
12.6.4 In respect of the EIA Regulations12
, specific criteria for measuring impacts will be applied to eachrelevant topic area. The initial stage will be based on the provision of a scale to identify the extentand magnitude of the impact i.e. high, medium, low or negligible.
12.6.5 The potential impacts arising from the proposed development will be assessed using a ‘7 point scale’,which primarily sets out the nature of the impact identified and its scale of significance.
12.6.6 The nature of the impacts are identified using the following expressions:
Adverse
Negligible
Beneficial
12.6.7 The following scale of significance is to be applied where an impact is identified as being adverse orbeneficial.
Minor
Moderate
Major
12.6.8 Significance is assessed as the magnitude or scale of the impact against the sensitivity of thereceptor or resource affected using the following matrix.
Table 12.2.2 Matrix of Significance
Sensitivity of Receptor/Receiving Environment to Change/Effect
High Medium Low Negligible
Ma
gn
itu
de
of
ch
an
ge/e
ffe
ct
High MajorModerate to
MajorMinor to
ModerateNegligible
Medium Moderate to Major Moderate Minor Negligible
12The Town and Country Planning (Environmental Impact Assessment) Regulations 2011,
http://www.legislation.gov.uk/uksi/2011/1824/pdfs/uksi_20111824_en.pdf
Low Minor to Moderate MinorNegligible to
MinorNegligible
Negligible Negligible Negligible Negligible Negligible
12.6.9 Residential premises, school and ancient monuments are classed as receptors of high sensitivity.Commercial premises are classed as receptors of medium sensitivity.
12.6.10 Following the categorisation of effects using the above methodology, further consideration of whetheran effect is significant in relation to the EIA regulations is carried out, with major and moderate effectsgenerally considered significant, but with professional judgement applied, taking account of theduration and frequency of the effect.
Criteria in relation to Construction Noise and Vibration effects12.7
Construction Noise
12.7.1 The noise levels generated by construction activities and experienced by any nearby noise sensitivereceptors, depend upon a number of variables, the most significant of which are:
the noise generated by plant or equipment used on-site, or on-site activities (i.e. the physical
demolition), generally expressed as sound power levels (LW);
the periods of operation of the plant on the site, known as its ‘on-time;
the distance between the noise source and the receptor and;
the attenuation provided by ground absorption and any intervening barriers.
12.7.2 The assessment of demolition and construction noise effects at residential properties will beundertaken according to the ‘example method 1 – the ABC method’ as defined in BS 5228-1:2009+A1:2014, Annex E and shown in Table 12.2.3.
Table 12.2.3 Construction Noise Level Thresholds of Potential Significant Effect at Dwellings
AssessmentCategory andThreshold ValuePeriod
Threshold Value LAeq,T (dB) facade
Category A (a) Category B (b) Category C (c)
Night-time (23:00 –07:00)
45 50 55
Evenings and Weekends(d)
55 60 65
Daytime (07:00 – 19:00)and
Saturdays (07:00 –13:00)
65 70 75
NOTE 1: A potential significant effect is indicated if the LAeq,T noise level arising from the site exceeds the thresholdlevel for the category appropriate to the ambient noise level.
NOTE 2: If the ambient noise level exceeds the Category C threshold values given in the table (i.e. the ambient noiselevel is higher than the above values), then a potential significant effect is indicated if the total LAeq,T noise level for theperiod increases by more than 3dB due to site noise.
NOTE 3: Applied to residential receptors only.
(a) Category A: Threshold values to use when ambient noise levels (when rounded to the nearest 5dB) are lessthan these values.
(b) Category B: Threshold values to use when ambient noise levels (when rounded to the nearest 5dB) are thesame as Category A values.
(c) Category C: Threshold values to use when ambient noise levels (when rounded to the nearest 5dB) arehigher than Category A values.
(d) 19:00 – 23:00 weekdays, 13:00 – 23:00 Saturdays, 07:00 – 23:00 Sundays.
12.7.3 For residential properties where construction noise levels are predicted to exceed the ABCthresholds, the assessment of the significance of the effect is based on professional judgement,taking into account a range of other factors including:
the layout and orientation of the property relative to the works
the number of receptors affected and the character of the impact
the timing, duration, frequency or likelihood of the effect.
12.7.4 However, it is fair to assume that if the ABC thresholds are exceeded the magnitude of the impactwould be high and the significance of the effect at residential receptors would be major adverse andtherefore significant.
12.7.5 In accordance with the NPPF and NPSE it is also necessary to identify receptors that exceed theLOAEL and SOAEL, and ensure adverse effects are mitigated and minimised
12.7.6 Table 12.2.4 defines the suggested LOAELs and SOAELs for the noise effect levels of demolitionand construction on residential properties.
Table 12.2.4 Construction Noise Effect Levels for Residential Buildings (facade levels) includingconstruction traffic.
Day LOAEL LAeq, T (dB) SOAEL LAeq, T (dB)
Daytime
(07:00 – 19:00 and Saturdays)
60 75
Evenings and Weekends
(19:00 – 23:00 weekdays, 13:00 –23:00 Saturdays and 07:00 –23:00 Sundays)
55 65
Any Night (23:00 – 07:00) 45 55
12.7.7 Should the existing ambient noise level already exceed the SOAEL, then on the basis thatconstruction noise should not increase the ambient noise level by more than 3 dB, the SOAEL is re-defined as equivalent to the ambient.
12.7.8 In relation to the schedule ancient monument (either side of Middle Wretchwick Farm), theassumption is made that it will be assessed using the same metrics as residential dwellings.
Vibration
12.7.9 The effects of human response to whole body vibration in buildings are defined in BS 6472-1: 200813
.This presents effects in terms of Vibration Dose Value (VDV). However, for human response toconstruction related vibration, it is considered more appropriate to measure Peak Particle Velocity(PPV mm/s), as suggested in BS 5228-2:2009+ A1:2014 Code of practice for noise and vibrationcontrol on construction and open sites Part 2: Vibration.
12.7.10 The limit of human perception to vibration is between about 0.15 mms-1
and 0.3 mms-1
PPV. Thesensitivity of the human body also varies according to different frequencies of vibration, withperception generally possible between 1Hz to 80Hz.
Whole Body Vibration
12.7.11 Table 12.2.5 adapts the guidance on the annoyance effects of vibration as provided in BS 5228-2:2009+ A1:2014 Annex B.
12.7.12 The onset of adverse effects (the LOAEL) is classified as 1 mms-1
PPV, the level at whichconstruction vibration can be tolerated with prior warning.
Table 12.2.5 Guidance on Effects of Vibration Levels
VibrationLevelPPVmm/s
Description of Effects Magnitude ofchange
Significanceof Effect
Adverseeffect Level
<0.3 Vibration is unlikely to be perceptible ineven the most sensitive situations formost vibration frequencies associatedwith construction.
Negligible Negligible
1 Increasing likelihood of perceptiblevibration in residentialenvironments.
Low Minor LOAEL
10 Increasing likelihood of complaint inresidential environments, but can betolerated at the lower end of the scale(near to 1) if prior warning andexplanation has been given toresidents.
Medium Moderate SOAEL
>10 Vibration is likely to be intolerable forany more than a very brief exposure to
a level of 10mms-1
.
High Major
Building Damage
12.7.13 BS 7385-2: 199314
provides guidance on vibration levels likely to result in cosmetic damage, and isreferenced in BS 5228-2:2009+A1:2014. Guide values for transient vibration, above which cosmeticdamage could occur, are suggested in Table 12.2.6.
Table 12.2.6 Transient Vibration Guide Values for Cosmetic Damage
Type of Building
Peak Component Particle Velocity in Frequency Range ofPredominant Pulse
4Hz to 15Hz 15Hz and above
Reinforced or framed structures
Industrial and heavy commercial
buildings
50mms-1 at 4Hz and above
13 BS 6472-1:2008 Guide to evaluation of human exposure to vibration in buildings. Vibration sources other than blasting
14 BS 7385-2: 1993 “Evaluation and measurement for vibration in buildings – Part 2: Guide to damage levels from groundborne vibration”
Unreinforced or light framed
structures
Residential or light commercial
buildings
15mms-1 at 4Hz increasing to20mms-1 at 15Hz
20mms-1 at 15Hz increasing to50mms-1 at 40Hz and above
NOTE 1: Values referred to are at the base of the building.
NOTE 2: For un-reinforced or light framed structures and residential or light commercial buildings, a maximumdisplacement of 0.6mm (zero to peak) is not to be exceeded.
12.7.14 BS7385-2:1993 states that the probability of building damage tends to zero for transient vibrationlevels less than 12.5 mms
-1PPV. For continuous vibration the threshold is considerably less at
around half this value.
12.7.15 It is also noted that these values refer to the likelihood of cosmetic damage. ISO 4866:201015
definesthree different categories of building damage:
cosmetic – formation of hairline cracks in plaster or drywall surfaces and in mortar joints of
brick/concrete block constructions;
minor – formation of large cracks or loosening and falling of plaster or drywall surfaces or cracks
through brick/block; and
major – damage to structural elements, cracks in support columns, loosening of joints, splaying
of masonry cracks.
12.7.16 BS 7385-2:1993 defines that minor damage occurs at a vibration level twice that of cosmetic damageand major damage occurs at a vibration level twice that of minor damage. Therefore, this guidancecan be used to define the magnitude of impact identified in Table 12.2.7.
Table 12.2.7 Magnitude of Change for Building Vibration
Continuous Vibration LevelPPV mms
-1Damage Risk Magnitude of change
<7.5 None Negligible
7.5 Cosmetic Low
15 Minor Medium
30 Major High
12.7.17 To consider the potential effects on the ancient monument (the medieval village), the guidance withinBritish Standard BS 7385: Part 2 can be used. The standard gives guidance on the levels of vibrationabove which the building structures could be damaged as shown in Table 12.2.8 below.
Table 12.2.8 Magnitude of change for vibration affecting listed buildings or ancient monuments
Building Structure Type IntermittentVibration ppv(mm/s)
Continuousvibration ppv(mm/s)
Magnitude of change
Listed Building or ancientmonuments
<5 <2.5 Negligible
Listed Building or ancientmonuments
5 2.5 Low
12.7.18 To determine what effects are caused by the vibration impacts, the sensitivity of the receptor will alsobe considered. Levels for cosmetic damage are considerably higher compared to human annoyancelevels and therefore the significance of this cannot be more adverse compared to the significance ofthe effect of vibration on human receptors.
12.7.19 Planning guidance relates to adverse effects on health and quality of life and therefore LOAEL andSOAEL values cannot be put forward in the assessment of vibration affecting buildings. Thesignificance of the effects for this receptor is therefore assessed using the EIA methodology.
Building Damage
15 ISO 4866:2010, Mechanical vibration and shock -- Vibration of fixed structures -- Guidelines for the measurement of
vibrations and evaluation of their effects on structure
12.7.20 BS 7385-2: 199316
provides guidance on vibration levels likely to result in cosmetic damage, and isreferenced in BS 5228-2:2009+A1:2014. Guide values for transient vibration, above which cosmeticdamage could occur, are suggested in Table 12.2.6.
Underground services
12.7.21 Advice in BS5228-2 states that some statutory undertakers have introduced criteria governing themaximum level of vibrations to which their services should be subjected. These criteria are usuallyconservative and it is recommended that the following limits be used in the absence of specificcriteria from the undertakers:
maximum PPV for intermittent or transient vibrations 30 mm·s−1;
maximum PPV for continuous vibrations 15 mm·s−1.
12.7.22 Criteria should be applied at the nearest point to the source or activity.
12.7.23 Even a PPV of 30 mm·s−1 gives rise to a dynamic stress which is equivalent to approximately 5% only of the allowable working stress in typical concrete and even less in iron or steel.
12.7.24 In the event of encountering elderly and dilapidated brickwork sewers, the base data should bereduced by 20% to 50%. For most metal and reinforced concrete service pipes, however, the valuesin a) and b) are expected to be quite tolerable. There is often some difficulty in assessing the truecondition of underground pipes, culverts and sewers. Among the factors which could mean that suchservices are in a state of incipient failure are poorly formed joints, hard spots, badly prepared trenchbases, distortion due to settlement or heave, or unstable surrounding ground caused by previous orexisting leaks. Operational Impacts
12.7.25 Therefore if predicted vibrations reach the levels in 12.7.21 the magnitude of change would be lowand the significance would be minor. If levels are predicted to be below these figures the magnitudeof change will be negligible and the significance will be negligible as well. As national policy isreferring to health effects it is not appropriate to set a LOAEL/SOAEL value.
Road Traffic Noise affecting existing sensitive locations
16 BS 7385-2: 1993 “Evaluation and measurement for vibration in buildings – Part 2: Guide to damage levels from groundborne vibration”
12.7.26 When assessing potential noise effects due to changes in road traffic flows as a result of adevelopment, it is appropriate to refer to the Design Manual for Roads and Bridges. The manual setsout noise assessment procedures to be followed when undertaking highway works such as buildingnew roads.
12.7.27 The DMRB provides useful guidance for assessing changes in road traffic noise due to variations inthe flow rate and vehicle composition of the traffic.
12.7.28 DMRB sets out thresholds at which potential effects may start to become apparent, based onchanges in 18-hour daytime noise levels (0600-2400h). The threshold is a change of 1 dB(A) whenassessing short term effects (i.e. comparing with- and without-development flows for the year ofopening of a road scheme) and 3 dB(A) when assessing long term effects (i.e. comparing with-development flows in a future year and without-development flows in the year of opening, where thefuture year can normally be considered to be the year during which the greatest traffic flows will occurwithin 15 years of opening).
12.7.29 In general, calculations are carried out of the Basic Noise Levels for the various scenarios, using themethodology set out in the Department for Transport document Calculation of Road Traffic Noise.
12.7.30 The calculations are based on traffic flow data which take account of the percentage made up ofHeavy Goods Vehicles and the stated speed limit for the road, or where available the actual speeds.The resultant noise level figure is the LA10, 18 hour (dB). For developments where complex or significantroad traffic noise effects due to highway works are not expected, it is appropriate to undertake theassessment in terms of changes in the Basic Noise Level defined at 10m from the edge of thecarriageway in CRTN. This does not relate directly to the noise exposure at individual residentialfaçades but is a reference noise level, comparison of which in various scenarios provides a goodindication of the noise level changes that are expected to occur along an existing road link where theroad itself is the dominant road traffic noise source.
12.7.31 On roads where 18-hour traffic flows (0600-2400h) are lower than 1000 vehicles per day this fallsoutside the scope of CRTN. On roads where this is the case it is not valid or appropriate to use thesame procedures to calculate resultant noise levels. It is relevant to consider any changes in noiselevels in the context of absolute noise levels in these instances. However in all cases, the 18-hourtraffic flows assessed here are greater than 1000 vehicles per day.
12.7.32 The DMRB also sets out thresholds for night time noise. These are identical to the daytimethresholds described above but with an additional lower threshold in terms of absolute noise level,below which effects are deemed to be negligible and therefore no further assessment is required.The absolute noise level threshold is 55 dBA Lnight (which is actually a LAeq, 8 hour value andcorresponds to the Interim Target in the WHO Night Noise Guidelines). The method of calculation ofLnight from traffic flow data can be found in a DEFRA document published for that purpose. Itscalculation is based entirely on the daytime LA10, 18 hour derived in accordance with CRTN. If a nightnoise assessment were to be undertaken on this basis, any changes in night time noise level will beidentical to changes in daytime noise level.
12.7.33 Arguably, if a night time noise level of 55 dBA is deemed acceptable then a daytime noise level of thesame magnitude would clearly also be acceptable. However it could also be argued that the Lnight
lower threshold of 55 dBA could be reduced to 40 dBA to correspond to the night noise guidelinevalue in the WHO document. Taking the WHO night noise guideline (NNG), interim target (IT) andguidance on daytime noise levels into account, as well as DMRB, if absolute noise level thresholdswere to be used (below which effects are deemed to be negligible) they could be set at 40 dBAduring the night and 50 dBA during the day. These levels correspond with those set out in the WHOGuidelines for Community Noise. It should be noted that Night Noise Guidelines published in 2009are not intended to replace the earlier Guidelines for Community Noise but to be referred to alongsidethem. Neither document forms part of any statutory requirement in the UK.
12.7.34 In summary, on the basis set out in the above paragraphs, it is appropriate to undertake theassessment purely in terms of changes in Basic Noise Level (LA10, 18 hour).
12.7.35 The proposed assessment criteria for the impact of road traffic upon existing dwellings are presentedin the following table:
Table 12.2.9 - Road Traffic Noise Assessment Criteria
Free fieldabsolute noiselevel, dB
Change in Noiselevel, LA10, 18h orLAeq, 16h
Magnitude ofnoise change inshort term
Magnitude of noisechange in long term
LAeq, 16h < 50 0 No change No change
0.1 to 0.9 Negligible Negligible
1.0 to 2.0 Low Negligible
≥3.0 Low Low
50 ≤ LAeq, 16h < 55
0 No change No change
0.1 to 0.9 Negligible Negligible
1.0 to 2.9 Low Negligible
3.0 to 4.9 Medium Low
≥5.0 Medium Medium
LAeq, 16h ≥ 55 0 No change No change
0.1 to 0.9 Negligible Negligible
1.0 to 2.9 Low Negligible
3.0 to 4.9 Medium Low
5.0 to 9.9 High Medium
≥10.0 High High
12.7.36 It should be noted that the presentation of changes in sound level to one decimal place in the table isnot a reflection of the accuracy of any assessment undertaken but rather serves to provide a clearthreshold between adjacent impact descriptions.
12.7.37 In relation to national policy on planning, the LOAEL could be set at 64 dB LAeq, 16hr as this correlateswith the level of road traffic noise which may trigger the provision of mitigation measures in the NoiseInsulation Regulations. The SOAEL could be set at 79 dB LAeq, 16 hours. LOAEL and SOAEL values areonly applicable in case the development increases road traffic noise levels at receptors. However,these values only apply if there is a predicted increase in noise levels due to the development (inaccordance with the sound insulation regulations). If there is a decrease in noise levels, this would beacceptable in planning terms.
Road Traffic Vibration affecting existing residential premises
12.7.38 The DMRB provides guidance on ambient levels of vibration as Peak Particle Velocities (PPV),stating that for traffic vibration generally a PPV of 0.3 mm/s measured on a floor in the verticaldirection is on the threshold of perceptibility. As such, the threshold criterion for traffic inducedvibration is a PPV rise to above a level of 0.3 mm/s or where an existing PPV above 0.3 mm/s ispredicted to increase. PPVs in the structure of buildings close to heavily trafficked roads rarelyexceed 2 mm/s and are typically well below 1 mm/s. The DMRB also states that there is no firmevidence that structural damage to buildings occurs below 10 mm/s.
12.7.39 DMRB recommends that the effects of vibration should be considered where appropriate. In the caseof ground-borne vibration, the likelihood of perceptible vibration being caused is particularlydependent upon the smoothness of the road surface. Research has shown that vibration levelscaused by heavy vehicles travelling at 110 km/h over a 25 mm hump (i.e. a large discontinuityconsistent with a poorly backfilled trench) could cause perceptible vibration at up to 40 m from theroad. This would infer that it is unlikely that significant levels of vibration would be generated atdistances greater than this. Also, with a newly laid road surface it is a requirement of new highwayconstruction specification that the surface would be smooth and free from any discontinuities of thismagnitude. DMRB, paragraph A5.26 states such vibrations are unlikely to be important whenconsidering disturbance from new roads and an assessment would only be necessary in exceptionalcircumstances.
12.7.40 New internal roads near existing noise sensitive receptors should have a smooth surface and be freefrom any discontinuities as per the DMRB’s guidance which should prevent any significant impacts onproposed dwellings.
12.7.41 The DMRB covers the potential for airborne noise, from heavy goods vehicles, to cause vibrationnuisance close to main roads. As an indication of the scale of impact relative to noise effects, theguidance in paragraph A6.21 (of DMRB) states that for a given level of noise exposure thepercentage of people bothered “very much” or “quite a lot” by vibration is 10% lower than thecorresponding figure for noise nuisance. On average traffic induced vibration is expected to affect avery small percentage of people at exposure levels below 58 dB LA10, 18 hr. Also, the significance ofany change in airborne traffic vibration can be considered proportional to the significance of changesin traffic noise. As such the assessment of airborne vibration can be considered to be included withinthe assessment of airborne noise. The effects of road traffic vibration are not considered in thisassessment.
Train Induced Vibration
12.7.42 Train induced vibration may be perceptible in lightweight residential dwellings when railtracks arelocated within a distance of around 50-80m from the dwellings. However, the proposed parametersplan does not include for any noise sensitive premises within this range and therefore the effects oftrain induced vibration are deemed negligible and not assessed further.
Industrial and Commercial Noise Including Fixed Plant Noise/Building Services and Service YardNoise
Ambient Noise Levels
BS 4142 Assessment
12.7.43 Regarding noise impact from a distribution centre, BS 4142:2014 provides an assessmentmethodology and criteria relating to:
sound from industrial and manufacturing processes;
sound from fixed installations which comprise mechanical and electrical plant and equipment;
sound from the loading and unloading of goods and materials at industrial and/or commercial
premises; and
sound from mobile plant and vehicles that is an intrinsic part of the overall sound emanating
from premises or processes, such as that from forklift trucks, or that from train or ship
movements on or around an industrial and/or commercial site.
12.7.44 The application of the standard is detailed below:
"This standard is applicable to the determination of the following levels at outdoor locations:
rating levels for sources of sound of an industrial and/or commercial nature; and
ambient, background and residual sound levels,
for the purposes of:
investigating complaints;
assessing sound from proposed, new, modified or additional source(s) of sound of an industrial
and/or commercial nature; and
assessing sound at proposed new dwellings or premises used for residential purposes."
12.7.45 Therefore, where onsite activity is concerned, the approach taken is in accordance with BS4142:2014. The rating level of noise from the facility is calculated, over a set time period, at each ofthe nearest noise sensitive locations. This rating level is then compared with the existing backgroundsound level.
12.7.46 The standard recommends the following reference time period, Tr, over which the specific soundshould be evaluated, for each of the day and night periods:
Tr = 1 hour during the day; and
Tr = 15 minutes during the night.
12.7.47 The standard states that daytime is typically between 07:00 h and 23:00 h. Accordingly night-time isbetween 23:00 h and 07:00 h.
12.7.48 The reason for the shorter night time period is identified in the standard as follows:
"The shorter reference time interval at night means that short duration sounds with an on time ofless than 1 h can lead to a greater specific sound level when determined over the reference timeinterval during the night than when determined during the day."
12.7.49 The rating level of noise for the assessment periods, LAr,Tr is the calculated noise level at thenearest receiver location, adjusted depending on the acoustic characteristic of the noise source.Adjustment factors are based on any tonality, impulsivity, intermittency and other soundcharacteristics present in the resultant noise level at the receiver position. The level orappropriateness of any penalty will depend both on the type of noise source and the context in whichit is perceived. Similarly, in accordance with BS 4142, the period of time for which an individual noisesource is active during the relevant reference time period will also be considered in establishing therating level.
12.7.50 It will also be necessary to consider the existing noise climate and what sound sources contribute toit. For example, where a noise generating activity is proposed adjacent to an existing identical noisegenerating site, the impact of the new noise source would be less than if it were to be planned in alocation where its character and type is different to and more noticeable than any existing noisesource nearby.
12.7.51 With regard to the background sound level against which the rating level is compared, the standardstates the following:
"In using the background sound level in the method for rating and assessing industrial andcommercial sound it is important to ensure that values are reliable and suitably represent both theparticular circumstances and periods of interest. For this purpose, the objective is not simply toascertain a lowest measured background sound level, but rather to quantify what is typical duringparticular time periods."
12.7.52 The periods of interest over a 24 hour day are usually related to day time activities (07:00- 23:00 h)and night time (23:00-07:00 h). However the standard makes the following statement:
"Among other considerations, diurnal patterns can have a major influence on background soundlevels and, for example, the middle of the night can be distinctly different (and potentially of lesserimportance) compared to the start or end of the night-time period for sleep purposes.Furthermore, in this general context it can also be necessary to separately assess weekends andweekday periods."
12.7.53 Therefore, the periods of time which are typically considered 'waking up' and 'falling asleep' stages,for example 23:00 to 24:00 h and 06:00 to 07:00 h, may need to be considered independently.Alternative periods may also be identified where breakdown beyond the standard day and night timeanalysis will be necessary, for example where background sound levels are shown to be regularlyelevated. Similarly both weekend and weekday periods may need to be considered separately, withcriteria set for both. The requirement to analyse specific time periods will be considered for each siteindividually.
12.7.54 Once the rating level at each receptor has been calculated reference can be made to the followingcommentary on BS 4142 in relation to assessing the impact based on the difference between therating level of the noise source and the pre-existing background sound level.
Typically, the greater this difference [between industrial site noise rating level and baseline
background level], the greater the magnitude of the impact.
A difference of around +10 dB or more is likely to be an indication of a significant adverse
impact, depending on the context.
A difference of around +5 dB is likely to be an indication of an adverse impact, depending on the
context.
The lower the rating level is relative to the measured background sound level, the less likely it is
that the specific sound source will have an adverse impact or a significant adverse impact.
Where the rating level does not exceed the background sound level, this is an indication of the
specific sound source having a low impact, depending on the context.
12.7.55 In addition to the above, BS 4142 also states:
"For a given difference between the rating level and the background sound level, the magnitudeof the overall impact might be greater for an acoustic environment where the residual sound levelis high than for an acoustic environment where the residual sound level is low.
Where background sound levels and rating levels are low, absolute levels might be as, or more,relevant than the margin by which the rating level exceeds the background. This is especially trueat night."
12.7.56 When assessing whether the existing sound levels are low, it is relevant to refer to the WHOGuidelines since where existing ambient noise levels in an area are low at night it has beenrecognised that these noise levels can be increased without significant detriment to residentialamenity.
12.7.57 For outdoor amenity areas during the daytime period the recommendation was to not exceed 50 dBLAeq, 16 hour to avoid people being moderately annoyed and 55 dB LAeq, 16 hour to avoid people beingseriously annoyed.
12.7.58 For indoor noise levels during the daytime period, the recommendation was to avoid exceeding 35 dBLAeq, 16 hour to ensure the noise does not interfere with normal speech. With open windows, this wouldcorrespond to approximately 45 dB LAeq, 16 hour as an external free field noise level. Where there areno other means of ventilation than opening windows, this level can be viewed as the LowestObserved Adverse Effect Level, below which "noise can be heard but does not cause any change inbehaviour or attitude" and above which "noise can be heard and causes small changes in behaviourand/or attitude, e.g. speaking more loudly".
WHO Night Noise Guidelines 2009
12.7.59 Table 3 of the executive summary of the NNG sets out effects of different levels of night noise on thepopulation's health. It indicates that an external level of 30 dB LAeq, 8 hour corresponds to the NoObserved Effect Level (NOEL) and that 40 dB LAeq, 8 hour corresponds to the Lowest ObservedAdverse Effect Level (LOAEL).
Absolute Noise Level Assessment Criteria
12.7.60 It is worth noting that the WHO guidelines distinguish various types of noise sources including road,rail and air traffic, as well as industry. They do not set industrial noise apart from the others and theydo not exclude industrial noise from the sources which can be covered by the guideline values.
12.7.61 It should also be noted that the WHO guideline noise levels discussed above are in terms of day andnight period noise levels (LAeq, 16 hour and LAeq, 8 hour respectively). BS 4142 uses shorter assessmentperiods for both the day (LAeq, 1 hour) and night (LAeq, 15 minute). Comparison of such shorter period noiselevels with the WHO guideline values can often result in quite different outcomes than comparison ofthe full day and night period noise levels. When noise sources are not entirely steady, examination ofshorter periods will indicate higher specific noise levels than examination of the full day or nightperiod. Using specific noise levels derived from the shorter assessment periods for comparison withthe WHO guidelines therefore represent a more stringent method than using the full day and nightperiods.
12.7.62 In addition, the BS 4142 rating level then includes adjustments for the character of the sound whereappropriate. For example if a sound source is highly impulsive, a penalty of 3 dB may be applied ifthe impulsivity is just perceptible at the receptor, 4 dB where it is clearly perceptible and 6 dB where itis highly perceptible. Comparison of a rating level derived in this way with the WHO guideline levels istherefore more stringent than a simple comparison of the specific sound level (without having appliedany penalties) with the guideline levels.
12.7.63 For the reasons presented in the preceding two paragraphs, comparison of BS 4142 rating levels(LAr,Tr) with the WHO guideline values represents a robust methodology.
12.7.64 Based on the above discussion, absolute ambient noise level thresholds are proposed along withcorresponding recommended actions in Table 12.2.9. It can be seen from the table that where dayand night rating levels are equal to or below 45 and 40 dB respectively, no further action orassessment is required.
12.7.65 In addition to these lower-level absolute limits it may be necessary to consider alternative absolute orrelative criteria where existing background sound levels are particularly high. These would beconsidered on a site by site basis.
Table 12.2.10 - Proposed BS4142 assessment criteria for absolute noise levels
BS4142 Rating LevelEquivalent PPGEffect Level Action
Magnitude ofchangeDaytime Night-time
LAr,T < 40 LAr,T < 30 No Observed EffectNo specific measuresrequired
LAr,T = 40 LAr,T = 30 NOELNo specific measuresrequired
40 < LAr,T < 45 30 < LAr,T < 40No Observed AdverseEffect
No specific measuresrequired
LAr,T = 45 LAr,T = 40 LOAELNo specific measuresrequired Low
45 < LAr,T < 55 40 < LAr,T < 45Observed adverseeffect
Mitigate and reduce to aminimum Medium
LAr,T = 55 LAr,T = 45 SOAELMitigate and reduce to aminimum High
55 < LAr,T ≤ 65 45 < LAr,T ≤ 55 Significant observedadverse effect Avoid
LAr,T > 65 LAr,T > 55
Unacceptableobserved adverseeffect Prevent
12.7.66 However, each site should be considered on its own merits and in some cases it may be appropriateto define thresholds at different levels to those in the above table.
12.7.67 On the above basis, where day and night rating levels are in excess of 45 and 40 dB respectively, itwill be necessary to consider the impact of the proposals with reference to the existing backgroundsound level and climate, in accordance with BS 4142. However such an assessment would also besubject to the primary assessment criteria contained in Table 12.2.10 above, such that there is noneed to reduce levels below 45 and 40 dB for the day and night periods respectively, even if the BS4142 comparative assessment indicates otherwise.
12.7.68 In this case the assessment basis presented in Table 12.2.11 is proposed where rating noise levelsexceed the thresholds identified above, by correlating the impact descriptions in BS 4142 and theeffect descriptions in planning policy guidance (Table 12.2.1). The table sets out equivalent PPGeffect levels and actions required for various relationships between the rating level of the noisesource at the receptor (LAr,Tr) and the background sound level at a location representative of thereceptor (LA90,T).
Table 12.2.11 - BS 4142 assessment criteria for comparative noise levels
BS4142 AssessmentEquivalent PPG EffectLevel Action
Magnitudeof change
LAr,T < LA90,T No Observed Effect No specific measures required
LAr,T = LA90,T NOEL No specific measures required
LA90,T < LAr,T < LA90,T+5 No Observed Adverse Effect No specific measures required
LAr,T = LA90,T+5 LOAEL17 No specific measures required17 Low
LA90,T+5 < LAr,T <LA90,T+10 Observed adverse effect16
Mitigate and reduce to aminimum18 Medium
LAr,T = LA90,T+10 SOAEL16Mitigate and reduce to aminimum17 High
LAr,T > LA90,T+15Significant observed adverseeffect16 Avoid17
17 Except where LAr,1hour ≤ 45 during the day or LAr,15minute ≤ 40 dB during the night, in which the effect is equivalent to LOAEL or NOEL.
18 Except where LAr,1hour ≤ 45 during the day or LAr,15minute ≤ 40 dB during the night, in which case no specific measures are required for noise occurring during the relevant day or night period
12.7.69 It can be seen from the above table that where the rating level is less than or equal to 5 dB above thebackground level, no action is required. It should also be noted that the thresholds in Table 12.2.9also apply, such that there is no need to reduce noise levels below 45 and 40 dB LAr,Tr for the day andnight periods respectively.
12.7.70 Tables 12.2.10 and 12.2.11 together therefore represent the proposed overall BS 4142 noiseassessment methodology in terms of LAeq (upon which the rating level LAr,Tr is based).
General Noise Events of Short Duration
12.7.71 BS 4142:2014 only calculates the impact of ambient noise levels generated by industrial activities atthe nearest noise sensitive dwellings over periods of 15 minutes at night (when potential sleepdisturbance is a factor which often needs to be considered) and one hour during the day. Thestandard accounts for the impulsivity of noise sources by including methods for adding a penalty, themagnitude of which depends on the degree to which the impulsivity is perceptible at a given receptor.
12.7.72 However in order to provide adequate protection to people trying to sleep in dwellings at night it isoften appropriate to consider noise events of short duration with reference to sources of guidanceother than BS 4142.
WHO Guidelines for Community Noise, 1999
12.7.73 Table 1 of the 1999 WHO document provides guideline values for community noise in specificenvironments. The relevant guideline value in this situation is 60 dB LAmax as a façade incident leveloutside bedrooms (which corresponds to approximately 57 dB as a free field level) during the nighttime, and is based upon the requirement to minimise sleep disturbance.
12.7.74 However, this criterion is considered to be an aspirational goal and in many locations is regularlyexceeded by common environmental and road traffic noise sources.
WHO Night Noise Guidelines, 2009 (NNG)
12.7.75 The NNG does not propose any new or updated outdoor LAmax criteria beyond those stated in the1999 Guidelines for Community Noise.
12.7.76 In Table 1 under the heading "Thresholds for Observed Effects" various levels corresponding to theonset of observable effects are cited, from 32 to 42 dB LAmax, inside. It is stressed that thesecorrespond to the points at which effects start to become observable. In many cases they may notstart to become significant until sound levels are much higher. However below table 3 on page XVIIthe following is stated:
"A number of instantaneous effects are connected to threshold levels expressed in LAmax. Thehealth relevance of these effects cannot be easily established. It can be safely assumed,however, that an increase in the number of such events over the baseline may constitute asubclinical adverse health effect by itself leading to significant clinical health outcomes."
12.7.77 Under the heading "Relation with the Guidelines for Community Noise (1999)" (page XVIII) thefollowing statements are made:
"The thresholds are now known to be lower than LAmax of 45 dB for a number of effects."
"to prevent sleep disturbances one should consider the equivalent sound pressure level and thenumber of sound events. The present guidelines allow responsible authorities and stakeholders todo this. Viewed in this way, the night noise guidelines for Europe are complementary to the 1999guidelines. This means that the recommendations on government policy framework on noisemanagement elaborated in the 1999 guidelines should be considered valid and relevant for theMember States to achieve the guideline values of this document."
12.7.78 The phrase "guideline values of this document" refers to the night period ambient noise levelguidance (LAeq, 8 hour) in the NNG. There are no guideline values expressed in terms of LAmax in theNNG.
12.7.79 Taking the above into account it is considered appropriate to continue to refer to the aspirationalguideline LAmax level in the 1999 WHO document, whilst also evaluating the number of occurrences ofelevated LAmax levels generated by the new sound source in comparison with pre-existing LAmax noiselevels and occurrences. Other guidance should also be referred to, as set out below.
BS 8233:2014 - Sound Insulation and Noise Reduction for Buildings
12.7.80 BS 8233 states the following regarding maximum noise levels within houses:
"Regular individual noise events (for example, scheduled aircraft or passing trains) can causesleep disturbance. A guideline value may be set in terms of SEL or LAmax,F depending on thecharacter and number of events per night."
12.7.81 The previous edition of BS 8233 included quantitative guidance with respect to night-time LAmax noiselevels in bedrooms within dwellings. BS 8233:2014 does not provide such guidance. However inparagraph 7.7.5.1.1 it is noted that the recommendations for ambient noise in hotel bedrooms aresimilar to those for living accommodation and Table H.3 in Annex H.3 gives example night-time LAmax
limits in hotel bedrooms of 45-55 dB. It is noted that night time specifically relates to the period 23:00-07:00 h.
12.7.82 BS 8233:2014 states the following regarding alternative means of ventilation:
"If relying on closed windows to meet the guide values, there needs to be appropriate alternativeventilation that does not compromise the façade insulation or the resulting noise level."
12.7.83 Therefore in the case of areas already subject to high existing maximum noise levels it is understoodthat achieving an internal noise level of 45-55 dB LAmax with windows open is not consideredreasonable. This is because the residents will already be used to the high prevailing noise levels andare likely to already be shutting windows, if required. The addition of new maximum noise levels of asimilar or lower level would not alter this behaviour.
12.7.84 In relation to free field external noise levels, sound insulation from typical single or double glazedwindows can be expected to vary between 25 and 30 dB(A) for road traffic type noise sources.Adding this to the minimum LAmax criterion of 45 dB gives an external criterion of between 70 and 75dB LAmax.
Other Guidance
12.7.85 In 1991 HMSO published 'Railway Noise - the report of the committee formed to recommend to thesecretary of state for transport, a national noise insulation standard for new railway lines'.
12.7.86 Whilst the document is concerned with railway noise it also reviewed research with respect to sleepdisturbance generally. It drew in particular from research by Rice and Morgan. This noted that ingeneral about 20% of the population have sleeping difficulties that are totally non noise related. Theyconcluded that it was unrealistic to set noise limits to ensure sleep would not be affected in any wayby noise. Reviewing various studies they suggested that sleep disturbance is significant when 25% ofthe population are likely to suffer some disturbance from all causes. Depending upon the noisesource, thresholds of 75-85 dB LAmax were proposed. For road traffic noise sources during the nighttime period 75 dB LAmax was the proposed threshold.
12.7.87 On other projects where noise impacts from similar activities were considered, the followingstatement has been upheld at planning appeal.
"Noise levels for short periods should not exceed 75 dB LAmax."
12.7.88 In conclusion, there are a number of LAmax criteria relating to external night time noise. The lowest ofthese, 60 dB from the World Health Organisation, represents an aspirational figure, corresponding toapproximately 57 dB as a free field level. Other criteria can be derived varying between 70 and 85dB.
Reversing Sounders
12.7.89 Reversing sounders represent a different type of noise source again and constitute a special case.The principles set out in this section therefore apply only to reversing sounders and not to any othersound sources.
12.7.90 Reversing sounders are specifically designed to attract attention and they often comprise anintermittent tone. An assessment of LAeq noise levels is not always appropriate for such anintermittent and distinctive source. Similarly, the previously discussed LAmax criteria may also not beappropriate on their own, due to fact that the noise source is specifically designed to attract attentionand has integral tonal and intermittent characteristics.
12.7.91 Although assessment in accordance with BS 4142 can take account of tonality and intermittency (bymaking allowance for penalties to account for such features), it may result in a misrepresentation ofthe noise impact where reversing sounders are concerned. Therefore the principle of addingpenalties set out in BS 4142 is used alongside consideration of LAmax for reversing sounders, withreference to the WHO Guidelines for Community Noise, which state:
“If the noise is not continuous, sleep disturbance correlates best with LAmax and effects have beenobserved at 45 dB or less. This is particularly true if the background level is low. Noise eventsexceeding 45 dBA should therefore be limited if possible."
"To prevent sleep disturbances, one should thus consider the equivalent sound pressure leveland the number and level of sound events. Mitigation targeted to the first part of the night isbelieved to be effective for the ability to fall asleep."
12.7.92 The above quotes indicate that effects can be observed at 45 dB. It does not necessarily indicate thatnoise levels of this order are likely to give rise to significant adverse effects, just that some effect canbe observed. Although the 2009 WHO Night Noise Guidelines state that it is now known that effectscan also be observable at lower levels, they do not propose any update to the LAmax guidance in the1999 Guidelines for Community Noise.
12.7.93 The internal LAmax noise level of 45 dB in the above quote equates to 60 dB as an external façadeincident level and to approximately 57 dB as an external free field level. In addition to taking theabove WHO guidance into account, it is reasonable to consider the tonality of reversing sounders. Asthese tonal sounders are specifically designed to attract attention, notable penalties can be applied inthis combination of BS4142 and LAmax assessment. A pessimistic total penalty of 12 dB (comprising 6dB for highly perceptible tonality, 3 dB for intermittency and 3 dB to account for the fact that thesound is specifically intended to attract attention) can be applied to reversing sounders in accordancewith BS4142, in order to give a worst case representation of the impact. These penalties are to beconsidered at each receptor and, where appropriate, applied to the calculated LAmax levels, forsubsequent assessment against the aspirational free field noise limit of 57 dB LAmax.
12.7.94 It should again be borne in mind that each situation should be examined on its own merits and theremay be cases where deviation from the above methodology is appropriate (for example in a casewhere conditions are such that the tonality of a reversing sounder would not be considered as highlyperceptible at a given receptor).
12.7.95 It is stressed that the principles set out above are specific to the special case of reversing soundersand are not applicable to other sound sources. It should be noted that an LAmax level from a reversingsounder can be thought of as akin to a short (e.g. 1 second) .LAeq; the LAmax level is likely to besustained for the duration for which the sounder actually sounds. This would not normally be the casefor other noise sources.
Guidance Summary
General Notes
12.7.96 It is noted that the below refers to external free-field noise levels. It must also be noted that the belowis a guideline only; in certain situations assessment criteria may be different.
Rating Levels for Site Noise
12.7.97 Where the rating level of the development at any given receptor is below the Lowest ObservableAdverse Effect Level (LOAEL) in absolute terms, no further action or assessment is necessary. TheLOAEL is considered to correspond to free field levels of 45 dB LAr, 1 hour during the day and 40 dB LAr,
15 minute during the night. Compliance with the LOAEL will ensure that significant effects in relation tothe EIA regulations do not arise.
12.7.98 It should be noted that this rating level will include all BS 4142 penalties for tonality and distinctivefeatures. Therefore comparison to the noise levels referred to in BS 8233 and WHO guidelinesrepresents a robust assessment.
12.7.99 Where the rating levels exceed the thresholds identified above, further BS 4142 assessment iscarried out with reference to Table 12.2.9 above.
Apportionment
12.7.100It is the intention that limits derived using the rating level methodology will apply to the total combinednoise level from an industrial site. This may include both B2 (general industrial) and B8 (storage ordistribution) uses, both of which may include items of fixed building services plant.
12.7.101To provide maximum flexibility for B8 uses, it is often desirable to set limits for B2 use and for fixedplant associated with B2 and B8 use at a level 10 dB lower than the overall limits for the site. Thisallows the B8 use to operate up to the overall site limit.
Impulsive Noise
12.7.102Where night time impulsive noise is concerned, the Lowest Observable Adverse Effect Level(LOAEL) is considered to correspond to a free field level of 57 dB LAmax. Therefore wheredevelopment includes impulsive events giving rise to night time noise levels of 57 dB LAmax or less, noaction or mitigation is required.
12.7.103Where development gives rise to night time noise levels in excess of 57 dB LAmax mitigation should beimplemented to reduce noise levels to 57 dB or less, or as close to 57 dB as reasonably practicable.
12.7.104Where existing noise levels already typically exceed 57 dB LAmax it would be reasonable to ensuredevelopment noise levels do not exceed existing LAmax noise levels in both level and typical rate ofoccurrence.
12.7.105The significance of the effects in relation to the EIA regulations will be derived based on the above inaccordance with professional judgment.
Reversing Sounders
12.7.106Where development noise events from sources designed specifically to attract attention (such asreversing bleepers) are concerned, night time noise levels should again not exceed 57 dB LAmax toensure the LOAEL is not exceeded. However a penalty of up to 12 dB should be applied to accountfor the fact that reversing sounders are specifically designed to attract attention and they exhibit tonaland intermittent characteristics.
Suitability of site for residential use12.8
12.8.1 The NPPF replaced the previous document used to assess the suitability of a site for residential use(PPG24). In order to assess the suitability of the site, LOAEL and SOAEL values should be putforward. SOAEL should generally be avoided and LOAEL values should be met using reasonablypracticable mitigation measures. This section describes the methodology used to propose suitablevalues for LOAEL and SOAEL and also contains a recommendation in relation to the risk ofoverheating in modern dwellings.
BS 8233:2014 Guidance on Sound Insulation and Noise Reduction for Buildings.
12.8.2 This Standard provides recommended guideline values for internal noise levels within dwellingswhich are similar in scope to guideline values contained within the World Health Organisation (WHO)document, Guidelines for Community Noise (1999). These guideline noise levels are shown in Table1, below.
Table 12.2.12 BS 8233 Desirable Internal Ambient Noise Levels for Dwellings
Activity Location 07:00 to 23:00 hours 23:00 to 07:00 hours
Resting Living room 35 dB LAeq,16h -
Dining Dining room/area 40 dB LAeq,16h -
Sleeping (daytimeresting)
Bedroom 35 dB LAeq,16h 30 dB LAeq,8h
12.8.3 The standard also provides advice in relation to design criteria for external noise. It states that:
“for traditional external areas that are used for amenity space, such as gardens and patios, it isdesirable that the external noise level does not exceed 50 dB LAeq,T, with an upper guidelinevalue of 55 dB LAeq,T which would be acceptable in noisier environments. However, it is alsorecognized that these guideline values are not achievable in all circumstances wheredevelopment might be desirable.
In higher noise areas, such as city centres or urban areas adjoining the strategic transportnetwork, a compromise between elevated noise levels and other factors, such as theconvenience of living in these locations or making efficient use of land resources to ensuredevelopment needs can be met, might be warranted. In such a situation, development shouldbe designed to achieve the lowest practicable levels in these external amenity spaces, butshould not be prohibited.
Other locations, such as balconies, roof gardens and terraces, are also important in residentialbuildings where normal external amenity space might be limited or not available, i.e. in flats,
apartment blocks, etc. In these locations, specification of noise limits is not necessarilyappropriate.
Small balconies may be included for uses such as drying washing or growing pot plants, andnoise limits should not be necessary for these uses. However, the general guidance on noise inamenity space is still appropriate for larger balconies, roof gardens and terraces, which might beintended to be used for relaxation.
In high-noise areas, consideration should be given to protecting these areas by screening orbuilding design to achieve the lowest practicable levels. Achieving levels of 55 dB LAeq,T or lessmight not be possible at the outer edge of these areas, but should be achievable in some areasof the space.”
World Health Organization, Guidelines for Community Noise, 1999 (WHO)
12.8.4 The World Health Organisation (WHO) Guidelines for Community Noise (1999) recommends suitableinternal and external noise levels based on dose response research. The levels recommend in thisguidance could be correlated to the LOAEL. Relevant guidance from this document is presentedbelow.
Sleep Disturbance (Night-time internal LOAEL) – as advised by the WHO
12.8.5 If negative effects on sleep are to be avoided, the equivalent sound pressure level should not exceed30 dBA indoors for continuous noise.
Interference with Communication (Daytime internal LOAEL) – as advised by the WHO
12.8.6 Noise tends to interfere with auditory communication, in which speech is a most important signal.However, it is also vital to be able to hear alarming and informative signals such as door bells,telephone signals, alarm clocks, fire alarms etc., as well as sounds and signals involved inoccupational tasks. The effects of noise on speech discrimination have been studied extensively anddeal with this problem in lexical terms (mostly words but also sentences). For communicationdistances beyond a few metres, speech interference starts at sound pressure levels below 50 dB foroctave bands centred on the main speech frequencies at 500, 1 000 and 2 000 Hz. It is usuallypossible to express the relationship between noise levels and speech intelligibility in a singlediagram, based on the following assumptions and empirical observations, and for speaker-to-listenerdistance of about 1 meter:
a. Speech in relaxed conversation is 100% intelligible in background noise levels of about 35 dBA,and can be understood fairly well in background levels of 45 dBA.
b. Speech with more vocal effort can be understood when the background sound pressure level isabout 65 dBA.
Annoyance Responses (Daytime external LOAEL for private amenity areas) – as advised by theWHO
12.8.7 During the daytime, few people are seriously annoyed by activities with LAeq levels below 55 dB; ormoderately annoyed with LAeq levels below 50 dB.
The Noise Insulation Regulations 1975
12.8.8 The Noise Insulation Regulations 1975 define the conditions under which dwellings are eligible fornoise insulation to control internal noise levels. The conditions relate to the level of traffic noise at thefaçade, the increase in noise levels as a result of the highway and the contribution of the new oraltered scheme to the noise level received at the façade.
12.8.9 Noise insulation qualification criteria must abide by a few tests which include the following two:
The facade noise threshold of 68dB LA1018h is met or exceeded;
That there must be a noise increase of at least 1dB(A) compared to the prevailing noise level
immediately before the construction of a highway or an additional carriageway were begun;
SOAELs for transportation airborne noise
12.8.10 Based on the noise insulation regulations a façade noise level of 69 B LA10 18h is therefore consideredas unacceptable and can trigger the provision of mitigation measures by the government. This levelcan therefore be used as the SOAEL in relation to transportation noise in England for new dwellings(and considered as LOAEL for existing dwellings). This level relates to a level of 64 dB LAeq 16h. Eventhough this level is predominantly proposed in relation to internal noise levels it can be used in thiscase as the SOAEL for external private amenity space (i.e. gardens). Based on guidance
19in
BS8233:2014, an external noise level of 64 dB LAeq 16h would roughly equate to an internal level of 49dB LAeq 16h. As daytime and night-time desirable target levels differ by 5 dB, a night-time SOAELcould be 44 dB LAeq 8h.
Proposed LOAEL and SOAELs for transportation airborne noise affecting new residentialdevelopments.
12.8.11 A summary of the proposed LOAEL and SOAEL is provided in Table 12.2.13 below.
Table 12.2.13: Proposed LOAEL and SOAEL for transportation noise affecting new dwellingsLevel Daytime (07:00 hours to
23:00 hours)Night-time (23:00 hours to 07:00hours)
LOAEL Internal 35 LAeq,16h (dB) 30 LAeq,8h (dB)
SOAEL Internal 49 LAeq,16h (dB) 44 LAeq,8h (dB)
LOAEL External 50 LAeq,16h (dB) Not applicable
SOAEL External 64 LAeq,16h (dB) Not applicable
High Speed Two Information Paper E20: Control of Airborne Noise from Altered Roads and theOperational Railway
12.8.12 The HS2 Information Paper E2020
describes the application of the aims set out in the NPSE thatrelate to airborne noise from roads and railway. In particular, it considers research findings onadverse effects on nonrestorative sleep which indicate that adverse effects on sleep can be avoidedif the maximum noise level inside the bedroom do not exceed 65 dB when more than 20 discreteevents occur. For this reason, a sound level of 80 dB LpAFMax at the façade when more than 20 trainpassbys occur and 85 dB LpAFMax at the façade when 20 or fewer train passbys occur are consideredthe SOAELs for operational railway noise at night. The LOAEL is set at 60 dB LpAFMax.
12.8.13 This paper has been through a review by a body called the Acoustic Review Group which includedmembers of the HS2 project as well as Government officials. It is considered that the HS2Information Papers relating to noise and vibration are effectively the Government’s interpretation ofits policy.
12.8.14 It should be highlighted that the Secretary of State approved assessment for the HS2 project includesa SOAEL of 65 dB LAeq,16h. The HS2 project also includes a LOAEL of 50 dB LAeq,16h. Therefore thedifference between the LOAEL and SOAEL for transportation noise in the Secretary of Stateapproved HS2 project is 15 dB.
Building Regulations12.9
Ventilation requirements for new dwellings
Background ventilation
12.9.1 Three types of ventilation are required under Part F21
of the Building Regulations. Whole buildingventilation provides nominally continuous air exchange which may be reduced or ceased when thebuilding is not occupied. It can be provided via background ventilators operating alone, or togetherwith:
passive stack ventilators;
continuous mechanical extract; or
19BS8233:2014 states that “If partially open windows were relied upon for background ventilation, the insulation would be
reduced to approximately 15 dB”20 https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/472175/E20_-_Control_of_Airborne_Noise_v1.4.pdf21 Building Regulations 2000, Part F Ventilation
continuous mechanical supply and extract with heat recovery.
12.9.2 Extract ventilation is applicable to rooms where most water vapour and/ or pollutants are released(e.g. kitchens and bathrooms). It can be provided by intermittent fans, passive stack or continuousmechanical extract with or without mechanical supply and heat recovery.
12.9.3 The 4 systems described in Part F do not present solutions which utilise the use of opening windowsfor background ventilation. Opening windows do not provide a controllable means of ventilation andalso pose security risks.
Purge ventilation
12.9.4 Purge ventilation is required throughout the building to aid the removal of high concentrations ofpollutants and water vapour. It is commonly provided simply by opening windows and doors.
12.9.5 Even though purge ventilation is recommended via opening windows, the temporary and intermittentoccurrence of this does not normally result in an unacceptable increase of internal noise levels.
12.9.6 Part F goes on to say that “Purge ventilation provisions may also be used to improve thermal comfort,although this is not controlled under the Building Regulations.”
Purge ventilation to reduce the risk of overheating
12.9.7 Part L1A22
states that reasonable provision should be made to limit solar gains and notes that solargains can be limited by an appropriate combination of window size and orientation, solar protectionthrough shading and other solar measures, ventilation (day and night) and high thermal capacity.
12.9.8 If residents are forced to open windows for a significant number of hours in order to mitigate the riskof overheating in their habitable spaces, internal noise levels should be considered.
12.9.9 BS5228:2009-A1:2014 Part 1 provides guidance on the acceptability of temporary exceedances oflimits related to noise insulation and temporary rehousing associated with construction noise. It statesthat the limits should not ideally be exceeded “for a period of 10 or more days of working in any 15consecutive days or for a total number of days exceeding 40 in any six consecutive months”. Eventhough not directly applicable, in the absence of any other relevant guidance, this advice may beincorporated into a suitable planning condition which will mitigate significant effects on health inrelation to noise and overheating. A possible condition could be the following:
“Occupants of dwellings with facade incident road traffic noise levels in the region of 58 dB LAeq 8
hours during the night-time or 63 dB LAeq 16 hours during the daytime should not be forced to open thewindows on these facades for comfort cooling purposes for a period of 10 or more days in any 15consecutive days or for a total number of days exceeding 40 in any six consecutive months. It isadvisable that for these dwellings, passive means of combating overheating are included using adynamic simulation thermal modelling analysis in compliance with CIBSE guidance andmethodology using the Design Summer Year (DSY) data and criteria with reference to CIBSE’sTM-52. If acceptable passive measures are deemed to be inadequate, low energy and carbonmechanical solutions (increased ventilation and/or cooling) should be put forward in order for aholistic solution to be found.”
Summary in relation to ventilation
22The Building Regulations 2010, Conservation of fuel and power, Part L1A
12.9.10 In summary, background ventilation for new residential dwellings should be provided via one of the 4systems in Approved Document F. The composite external building fabric should be designed toensure that appropriate internal noise levels due to external incident noise are met duringbackground ventilation. This can be secured via a planning condition.
12.9.11 Purge ventilation for new residential dwellings should be provided via open windows. The slightincrease of internal noise levels should be considered acceptable.
12.9.12 The need to open windows for thermal comfort (if advisable taking into consideration security or otherconcerns) in new residential dwellings (which experience high incident traffic noise levels) should bemitigated via the use of passive or active means (or a combination of the two) during the detaileddesign stage. This can be secured via a planning condition.
Noise Generated by Class A3, A4 and D2 Retail/Entertainment Units12.10
12.10.1 The development proposals allow for a small local centre with retail and community use which maycomprise of A1, A2, A3, A4, A5, D1, D2, B1 and/ or uses considered as sui generis.
12.10.2 Noise generated by these uses would adhere to the standards and requirements routinely imposedthe local authority by way of suitable planning conditions. The potential effect of noise associated withthe operation of these units will be assessed to existing and proposed noise sensitive receptors.
12.10.3 Any proposed retail units within the development proposals may comprise cafés, restaurants,drinking establishments, etc.
12.10.4 Such uses may have the potential to generate noise although the potential effects are unlikely to begreater than of negligible significance as the sound insulation afforded by the proposed facadeswould be more than sufficient for most uses.
Building Bulletin 93 (February 2015 edition)12.11
12.11.1 BB9323
, 2015 edition supersedes section 1 of ‘Building Bulletin 93’ (BB93) published in 2003. It setsout minimum performance standards for the acoustics of school buildings, and describes the normalmeans of demonstrating compliance with the Building Regulations. It also provides guidance insupport of the School Premises Regulations (2012) and the Independent School Standards (2013).
12.11.2 The acoustic conditions in schools are controlled by Part E of the Building Regulations, SchoolPremises Regulations and the Independent School Standards, which apply to new and existingschools.
12.11.3 Requirement E4 from Part E of Schedule 1 to the Building Regulations 2010 (as amended byStatutory Instrument, SI 2002/2871) states: “Each room or other space in a school building shall bedesigned and constructed in such a way that it has the acoustic conditions and the insulation againstdisturbance by noise appropriate to its intended use.” Approved Document E in support of theBuilding Regulations gives the following guidance: “In the Secretary of State’s view the normal way ofsatisfying Requirement E4 will be to meet the values for sound insulation, reverberation time andinternal ambient noise which are given in section 1 of Building Bulletin 93 ‘The Acoustic Design ofSchools’, produced by DfES.”
12.11.4 The School Premises Regulations and Independent School Standards applies to both new andexisting school buildings and contain a similar statement to that in Requirement E4 of the BuildingRegulations: “The acoustic conditions and sound insulation of each room or other space must besuitable, having regard to the nature of the activities which normally take place therein.” In addition tothe design and construction standards covered by the Building Regulations, the School PremisesRegulations and Independent School Standards cover the performance in use of schools includingspeech intelligibility in the classrooms. This means that in order to comply with the School PremisesRegulations and the Independent School Standards (but not the Building Regulations), operationalnoise levels (e.g. of equipment) in teaching and learning spaces will need to be suitable for theactivities taking place and open plan teaching and learning spaces in new and refurbished schoolswill need to provide adequate speech intelligibility as measured by the speech transmission index(STI). School client bodies are responsible for ensuring compliance with the School PremisesRegulations. The School Premises Regulations and Independent School Standards do not applyretrospectively.
12.11.5 Whilst planning permissions should not be subject to conditions that are covered by other legislation,such as the Building Regulations, local planning authorities may include conditions relating to noiseand acoustics when granting permission. These could cover such aspects as noise from schoolsaffecting nearby noise sensitive properties, or educational establishments where the acousticconditions are not subject to Requirement E4 of the Building Regulations.
23 BB93 Acoustic design of schools – performance standards
12.11.6 Where external ambient free field noise levels at the facade expressed as the LAeq,30mins, do notexceed the IANL figures given in Table 1 by more than 16 dB for single sided ventilated spaces and20 dB for cross ventilated or roof ventilated spaces, the criteria for natural ventilation can usually beachieved.
12.11.7 The lowest internal ambient level in Table 1 is 30 dB LAeq, 30 mins for teaching spaces intendedspecifically for students with special hearing and communication needs. Therefore if incident LAeq, 30
mins levels are below 46dB, the school can be naturally ventilated. It may be considered that this levelis the LOAEL for the purposes of the assessment, even though this level relates to a naturallyventilated school building.