TECHNICAL REPORT 35998-R1 - Proposed Residential Development Howlett of Lavenham, Sudbury Road, Lavenham CO10 9PJ Acoustic Design Statement
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Proposed Residential Development
Howlett of Lavenham, Sudbury Road,
Lavenham CO10 9PJ
Acoustic Design Statement
TECHNICAL REPORT
35998-R1
2
Proposed Residential Development
Acoustic Design Statement
Prepared for: Howlett of Lavenham, Sudbury Road, Lavenham CO10 9PJ
Site location: Howlett of Lavenham, Sudbury Road, Lavenham CO10 9PJ
Table of Contents
1 INTRODUCTION ............................................................................................................................... 4
2 NOISE CRITERIA ............................................................................................................................... 5
PROPG: PLANNING AND NOISE – NEW RESIDENTIAL DEVELOPMENT (2017) .................................... 5
3 PROPG STAGE 1 – INITIAL SITE RISK ASSESSMENT ......................................................................... 6
BACKGROUND SOUND LEVELS ............................................................................................................ 7
ACKNOWLEDGEMENT OF SURVEYING LIMITATIONS ......................................................................... 8
4 PROPG STAGE 2 – FULL ASSESSMENT ........................................................................................... 10
GOOD ACOUSTIC DESIGN PROCESS .................................................................................................. 10
INTERNAL NOISE LEVEL GUIDELINES................................................................................................. 10
EXTERNAL AMENITY AREAS .............................................................................................................. 13
OTHER DESIGN CONSIDERATIONS .................................................................................................... 14
5 CONCLUSIONS ............................................................................................................................... 15
Appendix A: Glossary of Acoustic Terms .............................................................................................. I
Appendix B: Annotated Site Location Plan .......................................................................................... II
Appendix C: Scheme Design ............................................................................................................... III
Appendix D: Environmental Survey .................................................................................................. VIII
Appendix E: Acousticians Qualifications and Status ........................................................................XIV
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Cornwall Suite, Dencora Business Centre, Whitehouse Road, Ipswich IP1 5LT
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PROJECT DOCUMENT
35998 35998-R1
NUMBER: REFERENCE:
ORIGINATED CHECKED
D. Attwell BEng. (Hons) AMIOA S. Skingle BSc. (Hons) MAES MIOA
Acoustic Consultant Principal Acoustic Consultant
RELEASE DATE CHANGE DESCRIPTION
1 14/01/2021 Original release
Sound Solution Consultants Limited (SSC) do not accept any liability in the event of technical reports
being used outside of their intended purpose detailed within our terms of engagement or if the report
is being relied upon by a third party without direct consent or contract with SSC.
INTRODUCTION 4
1 INTRODUCTION
1.1 A residential development has been proposed at Howlett of Lavenham, Sudbury Road, Lavenham
CO10 9PJ (hereinafter, “The Site”). A site plan highlighting the development site boundary in red
has been provided in Appendix B.
1.2 The proposed residential development has been noted to comprise of traditional form, terrace,
or semi-detached dwellings; 5 No. plots in total. Site layouts and elevation drawings have been
included in Appendix C of this report.
1.3 Access has been proposed from both the B1071 Sudbury Road and Melford Road, forming the east
and western boundaries of The Site. All plots have been set back from the roads, separated by
residential parking and vehicle turning areas.
1.4 The area surrounding The Site has been noted to be mixed residential and commercial. The
Howlett of Lavenham car showroom and vehicle maintenance unit, located to the north, has been
proposed for redevelopment in connection with the proposed residential application.
1.5 This document has been prepared to summarise a noise risk assessment in accordance with
ProPG: Planning & Noise Professional Practice Guidance on Planning & Noise New Residential
Development (May 2017).
1.6 A site-based study of environmental sound has been used to evaluate the acoustic environment
at The Site, in the context to the proposal for new residential development; accounting for current
industry guidance, including ProPG.
1.7 A Glossary of Acoustic Terms has been provided in Appendix A that may assist with the
terminology used within this report.
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NOISE CRITERIA 5
2 NOISE CRITERIA
PROPG: PLANNING AND NOISE – NEW RESIDENTIAL DEVELOPMENT (2017)
2.1 Professional Practice Guidance on Planning and Noise has been developed by a working group
consisting of representatives from the Association of Noise Consultants (ANC), Institute of
Acoustics (IOA), Chartered Institute of Environmental Health (CIEH) and practitioners from a
planning and local authority background. The guidance was made effective in May 2017 to
provide a recommended approach to the management of noise within the planning system in
England. The document draws upon the legislation, guidance and standards available at the time
of publication and reflects the Noise Policy Statement for England (NPSE), the National Planning
Policy Framework (NPPF) and Planning Practice Guidance (such as PPG-Noise), as well as other
authoritative sources of guidance.
2.2 The ProPG recommended approach involves two sequential stages covering an initial noise risk
assessment and then full assessment considering four key elements. These cover a good acoustic
design process, observing internal noise level guidelines, undertaking an external amenity area
noise assessment and consideration of other relevant noise issues.
2.3 The scope of ProPG considers new residential development that will be predominantly exposed
to airborne noise from transportation sources. In cases where the site is exposed to noise of an
industrial and/or commercial nature, this shall be considered at Stage 1 of the ProPG approach.
2.4 ProPG provides a summary of internal noise level guidelines as part of Stage 2 assessment
requirements. These guidelines are derived from British Standard BS 8233:2014 Guidance on
Sound Insulation and Noise Reduction for Buildings and The World Health Organisation Guidelines
for Community Noise (1999).
Daytime Night-time
Activity Location
07:00 – 23:00 23:00 – 07:00
Resting Living room 35 dB LAeq, 16 h -
Dining Dining room / area 40 dB LAeq, 16 h -
Sleeping 30 dB LAeq, 8 h
Bedroom 35 dB LAeq, 16 h
(daytime resting) 45 dB LAmax(F)
Table 1 – ProPG Internal Noise Level Guidelines.
2.5 The use of dB LAmax(F) as a health indicator during the night should be treated in correlation with
the overall dB LAeq, T value, considering the number of transient events that occur on a regular
basis.
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PROPG STAGE 1 – INITIAL SITE RISK ASSESSMENT 6
3 PROPG STAGE 1 – INITIAL SITE RISK ASSESSMENT
3.1 The environmental survey provided in Appendix D of this report describes the following period
sound pressure levels that have been used for an initial site risk assessment according to ProPG.
Sound Pressure Levels
Position Location Period
dB re. 20 µPa
Day time (07:00 – 23:00) 51 dB LAeq, 16 h
15 m south east of
1 Melford Road 42 dB LAeq, 8 h
(3 m above ground level) Night-time (23:00 – 07:00)
69 dB LAmax(F)*
Day time (07:00 – 23:00) 57 dB LAeq, 16 h
10 m west of Sudbury Road
2 47 dB LAeq, 8 h
(3 m above ground level) Night-time (23:00 – 07:00)
74 dB LAmax(F)*
* Value exceeded 10 times during entire night-time period, following latest industry guidance1.
Table 2 – Summary environmental sound pressure levels.
3.2 The dominant sound source at the site was noted from transportation sources, particularly
Sudbury Road running parallel to the east of The Site and, to a lesser extent, Melford Road along
the western boundary.
3.3 Melford Road was particularly noticeable at Position 1 which, for the majority of the study,
included a positive, westerly wind vector, beyond an underlying road traffic component from
Sudbury Road. At Position 2, Sudbury Road was noticeable from passing traffic to the east,
including occasional buses and agricultural vehicles.
3.4 Commercial activities were not observed at any point while monitoring at The Site, despite
Howlett of Lavenham service garage being in operation at the time of assessment (apart from
Sunday 11th 2020 when the business was shut). It has remained conceivable that garage
maintenance may be audible during summer months when shutter doors to vehicle bays are left
open for ventilation. External activities would generally be confined to cars moving around the
yard and occasional voices from workers. These operations have been assumed of low
intensification, in character with the area which is dominated by transport noise.
3.5 It has been understood that an application to redevelop Howlett of Lavenham will to be submitted
in connection with the residential proposal under assessment. The wider application has been
noted to include demolition of the existing buildings with plans to re-build with a new building
design and orientation of business activities. For the purposes of the environmental noise survey,
monitoring equipment was set at a maximum feasible height to minimise the acoustic effect of
any site features that will not remain on site, should the development proceed (in line with ProPG
recommendations2). Measurements taken at heights between 3 – 5 m represent sound levels
incident at proposed first-floor windows, deemed relevant for the proposal assessment.
1
Paxton, B. Conlan, N et al. Assessing Lmax for residential developments: the AVO guide approach. Proceedings
of the Institute of Acoustics. Volume 41, Part 1, 2019.
2
Paragraph 2.8 Professional Practice Guidance on Planning and Noise (ProPG) – 2017.
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PROPG STAGE 1 – INITIAL SITE RISK ASSESSMENT 7
3.6 Due to construction activities taking place at the adjacent site to the south, the survey was
undertaken over a weekend, outside of construction working hours. This ensured baseline
measurements were representative of the sound environment under typical conditions.
3.7 The initial site noise risk assessment has been categorised as ‘medium’ risk on the future
occupants of the new noise sensitive development, dictated by the measured maximum noise
events.
3.8 Where a medium noise risk has been noted, the pre-planning application advice stated in ProPG
is as follows:
“As noise levels increase, the site is likely to be less suitable from a noise perspective and any
subsequent application may be refused unless a good acoustic design process is followed and is
demonstrated in an ADS which confirms how the adverse impacts of noise will be mitigated and
minimised, and which clearly demonstrate that a significant adverse noise impact will be avoided
in the finished development.”
BACKGROUND SOUND LEVELS
3.9 The ‘typical’ background sound levels have been reported in this section in accordance with BS
4142 and have been established from histograms of the recorded LA90, 15min data at Positions 1 and
2. These are shown in Appendix D, Figures D5 and D6.
3.10 In line with Section 8.1.4 of BS 4142:2014+A1:2019, the monitoring duration should reflect
the range of background sound levels for the period assessed. In practice, there is no single level
for background sound as this is a fluctuating parameter, although a representative value of the
period should be used. Note this is not the lowest or mean average value of LA90,15min. From the
commentary of BS 4142, it has been recognised that:
“A representative level should account for the range of background sound levels and should not
automatically be assumed to be either the minimum or modal value.”
3.11 The following summary of dB LA90, T sound levels has been presented from the measured data
at Positions 1 and 2 of the environmental assessment. This has been established in accordance
with the assessment methodology of BS 4142.
Sound Pressure Levels
Daytime Measurement Data
dB LA90, T re. 20 µPa
Position 1 Position 2
Date Time HH:MM
Range Representative Range Representative
08/11/21 -
07:00 - 23:00 17 - 57 33 18 - 56 35
11/11/21
Table 3 – Background LA90, T sound pressure levels (daytime).
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PROPG STAGE 1 – INITIAL SITE RISK ASSESSMENT 8
ACKNOWLEDGEMENT OF SURVEYING LIMITATIONS
3.12 It has been acknowledged that the surveyed information in this report was recorded at the
beginning of January 2021, during the COVID-19 outbreak and where Government guidance3 of
4th January 2021 was in force, in the form of national lockdown, requiring people to “Stay at
Home”.
3.13 The COVID-19 outbreak has presented complications in obtaining representative baseline
sound levels primarily because typical road, air and rail transport usages have been reduced.
During the assessment, there were both travel restrictions and social distancing measures in place.
In turn, it has been acknowledged that environmental sound levels could have been reduced when
compared to “usual” conditions that might be expected during other times of the year and without
pandemic implications affecting environmental sound levels.
3.14 The Association of Noise Consultants (ANC) and the Institute of Acoustics (IOA) have recently
updated their guidance document, Joint Guidance on the Impact of COVID-19 on the Practicality
and Reliability of Baseline Sound Level Surveying and the Provision of Sound & Noise Impact
Assessments (Version 5, 1st September 2020)4. This document has set out changes in working
practices in the production of acoustic assessments, to minimise uncertainties when determining
baseline conditions, in a clear and transparent way.
3.15 The revised guidance has stated that, wherever possible, a site visit should be undertaken to
understand the sound environment and the sources contributing to the sound environment.
Where these may not be typical due to current circumstances then further reference may be
necessary.
“This can be supplemented by data from other sources such as using existing data (for example,
from previous local surveys and noise maps) or undertaking baseline sound predictions to establish
an appropriate robust estimate of baseline conditions.”
3.16 The guidance has advocated alternative methods of characterising baseline conditions so that
any outcome is representative, and the conclusions drawn are technically robust as possible.
These factors have been attempted in the preparation of this report where the author has duly
considered whether alternative sources of information in respect of environmental sound levels.
3.17 At the times of site survey and report writing, a residential development of 30 No. new homes
was notably under construction directly south of The Site. This proposal was granted planning
permission based on the information provided in noise assessment of 13th June 20175 produced
by Echo Acoustics Ltd. The environmental sound measurements listed within this document have
been used as a source of reference to review external noise levels from road traffic sources before
the effects of the COVID-19 outbreak.
3
National lockdown: Stay at Home - GOV.UK (www.gov.uk)
4
https://www.ioa.org.uk/sites/default/files/joint_guidance_on_the_impact_of_covid.ioa_anc_v5.pdf
5
DC_17_03100-Noise Assessment-3021444 Residential Development at Melford Road, Lavenham – Echo
Acoustics Ltd, 13th June 2017.
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PROPG STAGE 1 – INITIAL SITE RISK ASSESSMENT 9
3.18 The Table below has provided a comparison of measured sound levels against those reported
by Echo Acoustics in 2017 in pre-pandemic conditions. All sound pressure levels have been
adjusted to a nominal distance of 6 m from the nearest dominant road to the receptor (Echo
Acoustics survey locations have been shown in Figure 1 for reference).
Distance adjusted Sound Pressure Levels dB re. 20 µPa
noise data (6m Echo Acoustics Data (2017) SSC Data (2021)
from nearest road) 1.5 m above ground level 3.0 m above ground level
Daytime Night-time Daytime Night-time
Location
(07:00 - 23:00) (23:00 - 07:00) (07:00 - 23:00) (23:00 - 07:00)
West boundary 54 dB, LAeq, 16 h 47 dB, LAeq, 8 h 56 dB, LAeq, 16 h 48 dB, LAeq, 8 h
East Boundary 54 dB, LAeq, 16 h 54 dB, LAeq, 8 h 60 dB, LAeq, 16 h 52 dB, LAeq, 8 h
Table 4 – Comparison of data to review potential measurement differences.
Figure 1 – Noise measurement locations of Echo Acoustics Ltd Report 13th June 2017 (Figure 4)
3.19 While it has been noted that there are differences in the compared data in Table 4, such as
the measurement height and proximity to Howlett of Lavenham site, it can be seen that the
established baseline levels should be reasonably comparable to those which might otherwise be
considered during non-pandemic conditions from 2017.
3.20 For the purposes of providing noise risk assessment following ProPG, it has been reviewed in
summary, that the measured data has remained suitable for the purposes of establishing
commensurate noise risk and appropriate mitigation measures. In the avoidance of doubt, some
tolerance has been provided within the internal ambient noise level calculations, where worst-
case measured levels have been considered site wide.
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4 PROPG STAGE 2 – FULL ASSESSMENT
GOOD ACOUSTIC DESIGN PROCESS
4.1 ProPG states it is imperative for acoustic design to be considered at an early stage of the
development control process, as to avoid unreasonable acoustic conditions and prevent those
which are unacceptable.
4.2 The proposed development land space has been notably fixed in its locale, where it is not readily
possible to move the proposed receptors away from the incident noise sources, or visa-versa.
Given the dominant source as transport noise from the B1701 (Sudbury Road) and Melford Road,
providing the range of measured sound levels across the developing land space, there has been
considered little relative benefit in moving any plots in the proposal by any significant degree.
4.3 It has been noted that the orientation of all buildings allows for rear-facing amenity spaces, using
the intervening residential buildings as physical barriers between the incident transportation
noise source and proposed private gardens. This has been an example of good acoustic design
and reduces the requirement of alternative means of external amenity mitigation measures.
4.4 The plan layouts of each dwelling type have not been reviewed in detail within this assessment,
however initial plans shown in Appendix C generally demonstrate a good acoustic design, facing
less-sensitive rooms (i.e., kitchens and bathrooms) towards the dominant incident transport noise
sources where possible, in-line with industry guidance6.
4.5 It has been understood that all proposed dwellings are to be formed by traditional brick
construction along with an insulated and tiled roof. The sound insulation of these components
has been deemed less consequential to resulting internal ambient noise levels, where the acoustic
performance of glazing and ventilation elements will typically remain as dictating.
4.6 It has been noted that there could be some noise benefit in adding the development into the
available land space, such as the screening the residential dwellings currently under construction
from any commercial noise related to the Howlett of Lavenham site. The relative acoustic benefits
have otherwise been considered as somewhat limited in this regard.
INTERNAL NOISE LEVEL GUIDELINES
4.7 The proposed layouts in Appendix C have indicated that the residential façades most effected by
transport noise would be approximately 15 m and 17 m from the kerb of the two adjacent roads.
To account for this, measured sound level data has been corrected for distance based on moving
traffic behaving as a line-source for calculation purposes.
4.8 The adjusted sound pressure levels for east and west facing façades have been provided in Table
5 below as free-field values.
6
Figure 28 / Page 23. Sound Control for Homes. The Building Research Establishment. CIRIA, 1993.
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Sound Pressure Levels
Position Location Period
dB re. 20 µPa
17 m south east of Day time (07:00 – 23:00) 51 dB LAeq, 16 h
West facing
Melford Road (3m above 41 dB LAeq, 8 h
façades Night-time (23:00 – 07:00)
ground level) 68 dB LAmax(F)*
15 m west of Sudbury Day time (07:00 – 23:00) 55 dB LAeq, 16 h
East facing
Road (3m above ground 45 dB LAeq, 8 h
façades Night-time (23:00 – 07:00)
level) 70 dB LAmax(F)*
* Value exceeded 10 times during entire night-time period.
Table 5 – Summary of environmental sound pressure levels, adjusted to the position of the worst-
case residential façades proposed in site plans.
4.9 ProPG provides a summary of internal noise level guidelines as part of Stage 2 assessment that
have been replicated in Table 1 of this assessment.
4.10 The method adopted to achieve suitable internal noise level guidelines has been based upon
information contained within the recent ANC publication, The AVO Guide7. This has provided an
approach as to how the competing aspects of thermal and acoustic comfort can be managed and
has been written to reflect the requirements of ProPG and overarching planning requirements.
4.11 Given the initial site risk assessment in the worst-case, as ‘medium risk’, it has been
considered commensurate to judge suitable façade components in terms of windows and
ventilation. For ‘high risk’ sites, this information would be more-readily appraised in octave bands.
4.12 The range of whole dwelling ventilation strategies for development has been taken from The
Building Regulations 2010 Approved Document F (2013, as amended) Means of Ventilation. An
outline appraisal for suitability has been provided using Table B2 of the AVO Guide based on sound
levels incident on the worst-case building façades, summarised in Table 5 above.
Higher acoustic
Typical windows
Ventilation Strategy (according to ADF) performance
and vent
windows and vent
System 1: Intermittent extract fans
System 2: Passive stack ventilation
✓
System 3: Continuous mechanical extract (MEV) ✓
System 4: Continuous mechanical supply and
extract with heat recovery (MVHR)
✓ ✓
Table 6 – Outline appraisal of different ventilation strategies in accordance with ADF.
4.13 The following specifications have been based on calculations to the detailed method in section
G2.1 of BS 8233 (equivalent to the method in BS EN 12354-3). A typical small bedroom has been
considered at least 7.5 m2 with the glazed area of the façade at 25 % of the floor area.
7
Acoustics Ventilation and Overheating Residential Design Guide Version 1.1, January 2020.
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4.14 An adaptation term has been provided for all specifications following the method ISO 717-
1:2013. This includes a comparison between the normalised, A-weighted sound spectrum for day
and night against the adaptation curves for C and Ctr. Although the dominant sound source of
local traffic noise (< 50 km/h) does appear in either category of Table A1 of ISO 717-1, in this
instance the relevant spectrum adaptation term is C, as has been confirmed by visual comparison
of the spectral measurement results.
Metric with Example Configuration or
Façade component Specification
AdaptationTerm Proprietary Product
Velfac double glazing (glass-gap-
All windows ≥ 27 dB Rw + C
glass) 4-16-4 standard glass types
Through-window trickle
Trickle ventilator(s)* ≥ 29 dB Dne, w + C
ventilator, as rated
* If more than one ventilator is proposed per room, the specification will increase, see Table 8.
Table 7 – Minimum specifications for windows and ventilators.
4.15 In the case of System 1 and System 2 (see Table 6), where the total number of ventilators need
to achieve a suitable Equivalent Area for the entire dwelling, each habitable room may need to
contain more than one trickle vent. In this instance, the performance of the ventilator will need
to increase (by a factor 10 x log10 [n], where n is the number of vents per room). For example:
Quantity in Metric with
Façade component Specification
Room Façade Adaptation Term
1 ≥ 29
2 ≥ 32
Ventilators 3 ≥ 34 dB Dne, w + C
(per habitable room) 4 ≥ 35
5 ≥ 36
6 ≥ 37
Table 8 – Minimum specifications for ventilators, where one or more are used per habitable room.
4.16 The advice in this section has considered the internal ambient noise level with closed
windows. The AVO guide recommends that consideration is also given to the overheating
condition. With an advocated and simplistic insertion loss of 13 dB from external to internal areas
with an open window, the following summary has been provided for the worst-affected, east
facing façade with both closed and open windows.
Internal ambient noise level
Level 1 Risk Assessment following the AVO Guide
dB re. 20 µPa
Day Night Max
Location Windows Ventilation State
dB LAeq, T dB LAeq, T dB LAmax(F)
Window closed and
Building Ventilation 27 18 43
East facing ventilators open
façade Windows partially
Overheating Ventilation 42 32 57
open
Table 9 – Estimated IANL from different ventilation conditions.
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4.17 In case of closed windows, building ventilation conditions have been shown to provide
suitable internal ambient noise levels following ProPG and AVO, given that predicted values in the
above Table do not exceed those in Table 1.
4.18 The potential for adverse effects with open windows depends upon both the internal ambient
noise level and the frequency and duration of the overheating condition. There is no known
appraisal8 to determine the latter. The AVO guide provides that such assessment should be
optional, based on the measured external sound levels.
4.19 It has been noted from the AVO guide, that a material change in behaviour may occur with
internal ambient noise levels of > 50 dB LAeq, T (07:00 – 23:00) during the day, > 42 dB LAeq, T or > 65
dB LAmax(F) (23:00 – 07:00) during the night.
4.19.1 These values have not been exceeded by the simple calculations provided in the above Table,
therefore providing the initial estimation that opening windows could be acceptable at the
development when accounting for the worst-case façade.
EXTERNAL AMENITY AREAS
4.20 Private external amenity areas have been proposed for all residential units, as shown in Figure
C1 in Appendix C. Based upon daytime sound levels of 51 - 55 dB LAeq, 16h that have been predicted
at the front of the properties, shown in Table 4, all external amenity areas have been noted to fall
within ProPG guidance of 50 – 55 dB LAeq, 16h, as stated in BS8233:2014:
“… the acoustic environment of external amenity areas that are an intrinsic part of the overall
design should always be assessed and noise levels should ideally not be above the range 50 – 55
dB LAeq,16hr”.
4.21 All proposed plots have included private amenity areas to the rear of the dwellings; the centre
of each garden effectively screened from the traffic sources by both the proposed two-storey
residential buildings and (based on the latest layouts) the new commercial Howlett of Lavenham
showroom proposed along the northern boundary. The effect of this screening has been reviewed
as significant, in the region of 10 dB for all plots. At a central position within the gardens, the
effects of the dominant noise sources would be further reduced by distance propagation,
accounting for a further reduction from the dominant noise sources by at least 6 dB.
4.22 Where garden areas have been noted to extend around the sides of the dwellings (as shown
in Plots 1 and 5), solid fencing may wish to be employed. As a working approximation, it has been
expected that a screening loss of nominally 5 – 10 dB will occur where boundary fencing is of solid,
close boarded construction, as to interrupt line-of-sight partially or fully to the incident road
sources. There has been no over-bearing requirement for “acoustic” boundary screening given
the orientation of plots to the relative levels measured across The Site.
4.23 It has therefore been evident that the development would provide suitably protected, quiet
and tranquil outdoor spaces for all future residents.
8
CIBSE Technical Memorandum 59. Design methodology for the assessment of overheating risk in homes.
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OTHER DESIGN CONSIDERATIONS
4.24 The final element of Stage 2 assessment has been noted to consider other relevant issues
relating to the proposal, according to ProPG.
4.25 It has been understood that the proposal for 5 residential units is to be submitted in
connection with the proposal to redevelop the Howlett of Lavenham vehicle sales and workshop
units; located within the same plot of land to the north east. The latest designs have been
provided within Appendix C, Figures C4 and C5.
4.26 The combined layouts have illustrated a good acoustic design with pedestrian and vehicle
access located facing north east, towards the junction of Sudbury Road and Melford Road and
away from the proposed residential development. The remaining south west elevation has been
noted of solid brickwork without openings or glazing. The internal uses have been noted of office,
storage, reception and W/C’s, with vehicle bays within the maintenance area.
4.27 Based on the design and sizes of proposed rooms within the unit, it has been anticipated that
externally mounted or ventilating plant may be required to serve the internal spaces. This
mechanical plant has remained undefined within the joint proposal but has the potential to cause
adverse noise impacts on the adjacent residences if not correctly addressed; particularly in the
external amenity areas located to the rear of the dwellings.
4.28 ProPG has specifically referenced the need to provide acoustically suitable outdoor amenity
spaces and PPG-Noise in stating that:
“… unacceptable adverse effects should be prevented. Subject to other issues, national planning
policy does not require the prevention of adverse impacts, but instead requires that adverse
impacts be mitigated and reduced to a minimum.”
And lists examples of acoustic factors that influence whether noise could be a concern, including:
“the source and absolute level of the noise; the time of day noise occurs; the number, frequency
and pattern of noise events; the spectral content of the noise (i.e. whether or not the noise contains
particular high or low frequency content); the character of the noise (i.e. the presence of tones or
other features such as impulsiveness), possible cumulative impacts from several sources as well as
local topography.”
4.29 To minimise the potential for adverse impact within rear external amenity areas of the
proposed residential plots, it has been suggested that any externally mounted or ventilating plant
associated with the Howlett of Lavenham business be positioned either along the north east, north
west or south east sides of the proposed garage unit. Depending on the exacting equipment types
to be used, further attenuating measures have been considered likely (which could be in the form
of duct attenuators, louvres, screens or enclosures; as appropriate to the plant).
4.30 It has been advised that any externally positioned mechanical systems will need be subject to
future review where not available at this stage of planned development, therefore controlled by
way of a suitably worded planning condition.
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5 CONCLUSIONS
5.1 A study of environmental noise affecting a proposed residential development has been carried
out at Howlett of Lavenham, Sudbury Road, Lavenham CO10 9PJ.
5.2 Stage 1 assessment in accordance with ProPG Planning and Noise: New Residential Development
has provided that the site is influenced by dominant transport noise from the surrounding roads.
5.3 The initial site noise risk assessment has been categorised as ‘low risk’ on the future occupants of
the new noise sensitive development.
5.4 Stage 2 assessments in accordance with ProPG have reviewed a good acoustic design process,
internal ambient noise levels, external amenity areas and other matters. Commensurate design
specifications have been established considering latest industry guidance.
5.5 On the basis that design specifications within this report have been adopted, it follows that any
significant adverse noise impacts will be avoided in the finished development as to accord with
overarching planning requirements for new residential development.
5.6 A recommendation has been made to the decision maker to grant with a noise condition in
relation to unknown externally mounted or ventilating plant associated with the Howlett of
Lavenham business, to avoid adverse effects on the proposed residential development.
Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021Appendix A: Glossary of Acoustic Terms I Appendix A: Glossary of Acoustic Terms ‘A’ weighting dB(A): Correction applied to the frequency range of a noise in order to approximate the response of the human ear. Noise measurements are often A-weighted using an electronic filter in the sound level meter. Attenuation: Sound reduction, measured in decibels (dB). Ambient Sound: The totally encompassing sound in a given situation at a given time usually composed of sound from many sources near and far. Note: The ambient sound comprises the residual sound and the specific sound when present. Background sound level: A-weighted sound pressure level that is exceeded by the residual sound at the assessment location for 90% of a given time interval, T, measured using time weighting F and quoted to the nearest whole number of decibels. Calibration: A check of the function of a sound level meter by comparing the meter reading with a known sound pressure level. Decibel (dB): The unit of sound level and noise exposure measurement. The range of audible sound pressures is approximately 0 dB to 140 dB. Frequency (Hz): The pitch of the sound, measured in Hertz. LAeq,T: The A-weighted equivalent continuous sound pressure level during a period. It is the sound level of a notionally steady sound having the same energy as a fluctuating sound over a specified measurement period, T. Octave-bands: A division of the frequency range into recognised bands. Rating level, LAr,Tr: The specific sound level plus any adjustment for the character of the sound. Residual sound: Ambient sound remaining in the absence of the specific sound or that it is supressed as not to contribute to the ambient sound level. Residual sound level, Lr or Leq,T: The equivalent continuous A-weighted sound pressure level of the residual sound at the assessment location over a given reference time interval, T. Sound pressure level (SPL): The basic measure of sound, expressed in decibels, usually measured with an appropriate frequency weighting (e.g. the A-weighted SPL in dB(A)). Sound power level (Lw): The sound energy radiated per unit time by a sound source measured in watts (W). Sound power can be weighted (e.g. A-weighted) and is not influenced by environmental or physical factors such as weather or distance. Specific sound: Sound source being assessed. Specific sound level, Ls or Leq,T: The equivalent continuous A-weighted sound pressure level at the assessment position produced by the specific noise source over a given reference time interval, T. Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021
Appendix B: Annotated Site Location Plan II
Appendix B: Annotated Site Location Plan
Figure B1 – Location plan, annotated with survey measurement positions (both 3m AGL).
Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021Appendix C: Scheme Design III
Appendix C: Scheme Design
Figure C1 – Proposed development site plan.
Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021Appendix C: Scheme Design IV
Figure C2 – Proposed elevations and floor plans (Block of 2).
Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021Appendix C: Scheme Design V
Figure C3 – Proposed elevations and floor plans (Block of 3).
Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021Appendix C: Scheme Design VI Figure C4 – Proposed elevations and floor plans for Howlett of Lavenham garage redevelopment. Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021
Appendix C: Scheme Design VII
Figure C4 – Proposed street scenes of residential development and Howlett of Lavenham garage
redevelopment.
Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021Appendix D: Environmental Survey VIII
Appendix D: Environmental Survey
The equipment used conforms to BS EN 61672-1:2003 (Class 1) for sound level meters and BS EN
60942 (Class 1) for sound calibrators; with at least traceable calibration history valid; no greater than
two years for sound level meters and one year for sound calibrators, relevant to the times of the site
assessment.
Position Serial
Manufacturer Model No. Description
No. No.
Larson Davis LxT (SE) 3rd octave band sound level meter 3934
Position 1 Larson Davis PRMLxT1L Microphone preamplifier (low range) 29332
Larson Davis 337B02 ½” electret microphone 146990
rd
Larson Davis LxT (ST) 3 octave band sound level meter 4170
Position 2 Larson Davis PRMLxT1L Microphone preamplifier (low range) 36076
Larson Davis 337B02 ½” electret microphone 151485
Both Larson Davis CAL200 Sound level calibrator 11165
Table D1 – Sound monitoring equipment.
Validation checks at the end of the survey demonstrated acceptable drift across all parts of the study,
across the sound level measurement equipment used, of ≤ 0.20 dB. Interval data was recorded at the
measurement location at 1-minute and 15-minute periods, time synchronised to GMT.
Weather conditions at the times of site attendance were deemed acceptable for surveying.
Weather
Start Finish Additional comments
conditions
Wind velocity < 3 m/s Average < 4 m/s Average
Wind direction N W
None
Cloud cover/rain 0 %, no rain 0 %, no rain
Temperature 0 °C 5 °C
Table D2 – Recorded weather conditions.
A brief description of the measurement positions has been provided below:
Position 1) Incident sound was observed predominantly from Melford Road which at the times
of observation included a neutral wind vector. Construction activity was audible and visible to
the south east where a residential roof was being constructed. The first and last hours of
measurement were removed from the assessment period where construction work affected
the survey results. No commercial activity was observed.
Position 2) Incident sound was observed predominantly from Sudbury Road (B1071) which at the
times of observation included a neutral wind vector. Rooftop construction activity was also
audible and visible to the south west and, like Position 1, these periods of measurement were
removed from the assessment. No commercial activity was observed other than a car pulling
into the car park of the commercial yard while the sound level meter was being set up.
Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021Appendix D: Environmental Survey IX
Figures D1 and D2 – Photo highlighting Measurement Positions 1 and 2.
Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021Appendix D: Environmental Survey X Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021
Appendix D: Environmental Survey XI Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021
Appendix D: Environmental Survey XII Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021
Appendix D: Environmental Survey XIII Sound Solution Consultants Limited Doc ref: 35998-R1 14/01/2021
Appendix E: Acousticians Qualifications and Status XIV
Appendix E: Acousticians Qualifications and Status
Dominic Attwell BEng. (Hons) AMIOA
Position Held: Acoustic Consultant.
Qualifications: BSc. (Hons) Audio Acoustics.
Affiliations: Associate Member of the Institute of Acoustics.
Acoustics Experience: 4 years.
Steve Skingle BSc. (Hons) MAES MIOA
Position Held: Principal Acoustic Consultant.
Qualifications: BSc. (Hons) Acoustics.
Institute of Acoustics Diploma in Acoustics and Noise Control.
Affiliations: Corporate Member of the Institute of Acoustics.
Corporate Member of the Audio Engineering Society.
Acoustics Experience: 18 years.
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