Gordon Brown MCIEH, FIOA, The Old School, Ipswich Road, Gosbeck, Suffolk IP6 9SN

Tel 01449 760689 Mobile 07880 715228 E-mail gordon@10db.co.uk Website at www.10db.co.uk

NOISE EXPOSURE ASSESSMENT OF A PROPOSED RESIDENTIAL DEVELOPMENT ADJACENT TO AN INDUSTRIAL ESTATE

LAND AT GREEN LANE WEST, RACKHEATH, NORFOLK

Client: Mr Paul Clarke, Brown & Co, The Atrium, St. George's Street, Norwich, Norfolk,

NR3 1AB

Brief: To advise on the layout and design of a proposed residential development at

the above site, which is potentially exposed to noise from an adjacent

industrial estate, to ensure that satisfactory noise levels can be achieved

within the proposed dwellings.

Site: Land at Green Lane West, Rackheath, Norfolk.

Dates: Noise measurements 27/28 August 2015

This report 7 September 2015

Author Gordon Brown MCIEH, FIOA

2

CONTENTS

Page No

1 OBJECTIVES 3

2 NOISE LEVEL MEASUREMENT & ASSESSMENT 4

3 CONCLUSIONS & RECOMMENDATIONS 9

4 NOISE MEASUREMENT EQUIPMENT 10

5 APPENDIX 1 – MEASUREMENT LOCATION PLAN 11

6 APPENDIX 2 – MONITORING RESULTS 12

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1. OBJECTIVES

1.1. A site proposed for residential development (shown in Appendix 1) is bounded on its

northern side by the Rackheath Industrial Estate, and is therefore potentially affected

by noise from this source. The site owner has requested an investigation into the effect

of this factor on the development with a view to informing the design of the

development and incorporating mitigation measures where necessary.

1.2. The Environmental Health Officer, Mr Duke, has confirmed that road traffic noise from

Green lane West is not a significant issue as road traffic flows are relatively low, as are

average speeds.

1.3. This report describes the investigation of the noise levels prevailing on the site and

advises if it is necessary to include any mitigation or design features to give protection

from noise for the future occupiers.

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2. NOISE LEVEL MEASUREMENT & ASSESSMENT

2.1. The Rackheath Industrial Estate that forms the northern boundary of the site is the

only local noise source likely to have a significant effect on the development, but the

site is heavily shielded from the industrial estate by the bulk of the buildings located

along the boundary. These buildings are high and have no openings on the facades

facing the development site. There are also no fans or other equipment located along

this boundary. The various businesses that occupy buildings along the boundary do not

appear to operate outside normal business hours and a preliminary visit indicated that

no significant noise emissions could be attributed to activities on the estate.

2.2. In order to determine if significant noise emissions were likely from this source two

environmental noise measurement systems were installed on the development site

adjacent to the northern boundary, and measurements made covering the night time

and daytime periods. Weather constraints limited the duration of measurement, but

approximately 20 hours of measurement was carried out. In addition to measuring

noise levels each meter also recorded a contemporaneous audio track that allows

attribution of noise events to particular activities or sources.

2.3. The results of the measurement exercise are shown in detail in Appendix 2, and

indicate that overall noise levels on the site are low both during daytime and at night.

There is little difference between noise levels measured near Green Lane West

(position 1) and near the rear of the site (position 2), daytime levels being 50dB

LAeq,16hours near to Green Lane West and 48dB LAeq,16hours at the rear of the site. Night

time levels were 40dB LAeq,8hours at both positions.

2.4. Examination of the audio recording indicates that there are no significant noise

emissions from the industrial estate, although it was possible to hear some noise from

the use of a grinder for a short period from 13:36 to 13:46 on 28 August. The

measured noise level from this activity was slightly above the ambient level and only

just detectable on the audio recording. The most significant source of noise affecting

5

the site originated from aircraft, both civilian aircraft using Norwich City airport and

military jets from the bases in the region.

2.5. The National Planning Policy Guidance (NPPG), published March 2014, gives some

detail on how noise should be considered in the context of the planning system but

does not include any defined noise limits, the advice that is given in the NPPG being as

follows;

Local planning authorities’ plan-making and decision taking should take account of

the acoustic environment and in doing so consider:

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.

In line with the Explanatory Note of the Noise Policy Statement for England, this

would include identifying whether the overall effect of the noise exposure (including

the impact during the construction phase wherever applicable) is, or would be,

above or below the significant observed adverse effect level (SOAEL) and the lowest

observed adverse effect level (LOAEL) for the given situation.

2.6. There are two primary sources of guidance on the effects of noise on residential

properties; the World Health Organisation Guidelines for Community Noise 1999 and

BS8233:2014 Sound Insulation and Noise Reduction for Buildings. The WHO

recommendations are that, "During daytime, few people are highly annoyed at LAeq

levels below 55dBA and few are moderately annoyed at LAeq levels below 50dBA". The

figures of 55dB and 50dB are understood to be "free field" and the time period over

which daytime is assessed is the 16 hours from 07:00 to 23:00. PPG24 used the level of

55dB LAeq,16hours as the level below which noise was not a significant consideration in

planning terms.

2.7. BS 8233:2014 advises the following noise criteria for internal residential areas:

Living rooms during the daytime – 35 dB LA LAeq,16hr.

Dining rooms during the daytime – 40 dB LA LAeq,16hr.

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Bedrooms - 35 dB LA LAeq,16hr during the day (for rest) and 30 dB LAeq,8hr at night

(for sleep).

2.8. The previous version of the Standard (1999) suggested that a window, when partially

open, will provide approximately 10 to 15 dB Rw of sound attenuation; this reference is

now removed from the latest iteration of the Standard but the worked example (G.1)

at Annex G of the current Standard suggests that a partially open window would

provide sound attenuation of approximately 15 dB Rw. The current version of the

Standard also suggests that “standard insulating glass units have an insulation value of

approximately 33 dB Rw” when closed.

2.9. In respect of noise in external areas, BS8233:2014 states; “For traditional external

areas that are used for amenity space, such as gardens and patios, it is desirable that

the external noise level does not exceed 50 dB LAeq,T, with an upper guideline value of

55 dB LAeq,T which would be acceptable in noisier environments. However, it is also

recognized that these guideline values are not achievable in all circumstances where

development might be desirable. In higher noise areas, such as city centres or urban

areas adjoining the strategic transport network, a compromise between elevated noise

levels and other factors, such as the convenience of living in these locations or making

efficient use of land resources to ensure development needs can be met, might be

warranted. In such a situation, development should be designed to achieve the lowest

practicable levels in these external amenity spaces, but should not be prohibited.”

2.10. Although the previous guidance in respect of planning and noise, PPG24, has now been

discontinued as official guidance it does provide guidance on the typical noise

reduction of dwelling facades with windows, which gives an indication of the noise

levels likely to be generated by each of transport based noise sources under

consideration. This advice is still valid and is shown in Table 1 below.

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Table 1 - Typical noise reduction of a dwelling facade with windows set in a

brick/block wall. Values are with windows closed.

Difference between dB(A) levels outside and inside

Noise Source Single glazing Thermal double glazing Secondary glazing

Road Traffic 28 33 34

Civil Aircraft 27 32 35

Military Aircraft 29 35 39

Diesel Train 28 32 35

Electric Train 30 36 41

Note: The values in the table above are the difference between dB(A) levels measured

outside and inside typical dwellings; they have not been corrected for reverberation

time or window area, and so cannot be compared with values obtained under other

conditions. The Table is intended to give an idea of the insulation likely to be achieved

in practice - not under ideal conditions. Secondary glazing systems in particular will

perform better in installations where sound insulation is not limited by poor sealing or

by flanking sound paths such as through doors or acoustically weak parts of window

bays. The values for single glazing are representative of well-sealed windows.

2.11. Assuming that a partially open window will give 15dB attenuation of external noise

levels and that the primary noise source is civil aircraft, the levels inside rooms

attributable to external noise sources will be as shown in the following table;

P1 Day P2 Day P1 Night P2 Night

Measured level 50dB 48dB 40dB 40dB

Level with Windows partially open 35dB 33dB 25dB 25dB

Level with Single glazing (closed) 23dB 21dB 13dB 13dB

Level with Double glazing (closed) 18dB 16dB 8dB 8dB

Level with Secondary glazing (closed) 15dB 13dB 5dB 5dB

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2.12. All of the predicted internal noise levels are well within the recommended values given

in BS8223:2014, even with windows open. Daytime noise levels in external spaces will

also meet the WHO and BS8233:2014 50dB LAeq,16hours criterion.

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3. CONCLUSIONS & RECOMMENDATIONS

3.1. The noise exposure of the site has been assessed and both external and internal noise

levels of the new dwellings will be satisfactory with no requirement for any specific

mitigation measures. Noise emissions from the industrial estate are currently so low as

to not be a significant planning consideration, and road traffic noise is also at a

relatively low level.

3.2. There remains the minor potential for noise to affect the development site if there are

significant changes to operations on the industrial estate and it would be prudent to

design the site layout to maximise the distance between the proposed dwellings and

the boundary with the industrial estate. This may be done by placing any amenity

areas on that boundary and/or by placing the site access road between the industrial

estate and the dwellings.

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4. NOISE MEASUREMENT EQUIPMENT

4.1. Sound Level Meters: two Svan 971 type 1 instruments, complete with all accessories,

including MOLES environmental microphone systems. The meters incorporate full

integrating facilities to determine true average sound levels (Leq,T), and the capability

to measure time profiles using different time constants and frequency weightings. The

meters are able to measure levels in 1/1 octaves, 1/3 octaves. A matching acoustic

calibrator Grade 1 instrument was used for checking the accuracy of the sound level

meters, before and after making noise measurements.

4.2. All equipment is calibrated to UKAS or manufacturers standards and accompanied by

current calibration certificates.

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APPENDIX 1 – MEASUREMENT LOCATION PLAN

North

Position 1

Position 2

12

Logger r esults, aggregation degree = 44

22:00:00

27/08/2015

00:00:00

28/08/2015

02:00:00

28/08/2015

04:00:00

28/08/2015

06:00:00

28/08/2015

08:00:00

28/08/2015

10:00:00

28/08/2015

12:00:00

28/08/2015

14:00:00

28/08/2015

16:00:00

28/08/2015

18:00:00

28/08/2015

Time

25.0 25.0

30.0 30.0

35.0 35.0

40.0 40.0

45.0 45.0

50.0 50.0

55.0 55.0

60.0 60.0

65.0 65.0

dB

Acoustic p

ressure

Acoustic p

ressure

dB

Start Duration LAeq (TH) LAeq (SR)

Info - - Ch1, P1 (A, Lin) Ch1, P1 (A, Lin)

Main cursor 27/08/2015 21:28:54 - 50.6 dB 41.7 dB

Audio 27/08/2015 21:28:10 19:15:28.000 45.8 dB 45.8 dB

Logger r esults, aggregation degree = 44

22:00:00

27/08/2015

00:00:00

28/08/2015

02:00:00

28/08/2015

04:00:00

28/08/2015

06:00:00

28/08/2015

08:00:00

28/08/2015

10:00:00

28/08/2015

12:00:00

28/08/2015

14:00:00

28/08/2015

16:00:00

28/08/2015

18:00:00

28/08/2015

Time

25.0 25.0

30.0 30.0

35.0 35.0

40.0 40.0

45.0 45.0

50.0 50.0

55.0 55.0

60.0 60.0

65.0 65.0

dB

Acoustic p

ressure

Acoustic p

ressure

dB

Start Duration LAeq (SR) LAeq (TH)

Info - - Ch1, P1 (A, Lin) Ch1, P1 (A, Lin)

Main cursor 28/08/2015 16:50:04 - - 48.6 dB

Audio 27/08/2015 21:21:46 19:28:17.000 47.7 dB 47.8 dB

Overload (TH) 27/08/2015 21:21:56 00:00:02.000 44.9 dB 49.4 dB

APPENDIX 2 – MONITORING RESULTS

(Red line is LAeq,1second, Blue line is LAeq,15minutes. All high level transient events are due

to birdsong, road traffic, or aircraft)

Position 1 – near Green Lane West

Position 2 – at rear of site