PROPOSED RESTAURANT UNIT 1, THE SQUARE, HALE BARNS NOISE IMPACT ASSESSMENT On behalf of: Cut Restaurants Ltd
Report No: P16-083-R01v2 February 2016
PROPOSED RESTAURANT UNIT 1, THE SQUARE, HALE BARNS NOISE IMPACT ASSESSMENT
Report prepared by: Hepworth Acoustics Ltd 21 Little Peter Street Manchester M15 4PS
On behalf of: Cut Restaurants Ltd
Report prepared by: David Thurstan BSc MIOA, Senior Consultant
Report checked by: Donald Quinn BSc MIOA – Managing Director
CONTENTS
1.0
INTRODUCTION
1
2.0
SITE DESCRIPTION
3
3.0
SOUND INSULATION TESTING
4
4.0
BACKGROUND NOISE MEASUREMENTS
5
5.0
NOISE IMPACT ASSESSMENT & RECOMMENDATIONS
6
6.0
SUMMARY
11
FIGURE 1 – NOISE MEASUREMENT LOCATIONS
12
FIGURE 2 – PROPOSED SITE LAYOUT
13
APPENDIX I: NOISE UNITS & INDICES
14
APPENDIX II: NOISE SURVEY RESULTS
17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
1.0
INTRODUCTION
1.1
Hepworth Acoustics Ltd was commissioned by Cut Restaurants Ltd to carry out a noise impact assessment in connection with a proposed restaurant at Unit 1, The Square, Hale Barns.
1.2
The noise assessment has been requested in connection with relevant planning conditions and landlord’s requirements in respect of the development.
1.3
Conditions 22 and 23 of the planning consent (82098/VAR/2014) are as follows: 22. The noise levels from fixed electrical and mechanical plant on the site, when rated in accordance with BS4142:1997, shall not exceed 35 dB(A). The noise levels shall be determined at one metre outside the façade containing a window to a habitable room in the nearest noise sensitive property (including All Saints Church). The noise level assessment shall be made in accordance with BS4142:1997. 23. Within two months of the date of this permission, details of measures for the control of noise intrusion into the residential apartments and noise emission from the Class A units shall be submitted to the Local Planning Authority for approval. The development shall not be carried out other than in accordance with the details as approved in writing by the Local Planning Authority.
1.4
We understand that the landlord’s requirements are to meet the requirements of planning conditions 22 and 23.
1.5
We have been commissioned by the client to carry out the following:
An inspection of the site and surrounding area;
Indicative sound level difference testing between the unit and an apartment immediately above;
A noise survey to establish the existing noise climate over a weekday evening period;
An assessment of the potential impact of trading noise transmission to the apartments above;
Providing advice on appropriate mitigation measures where necessary.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 1 of 17
Cut Restaurants Ltd
1.6
Proposed Restaurant, Unit 1, The Square, Hale Barns
The various noise units and indices referred to in this report are described in Appendix I. All noise levels mentioned in the text have been rounded to the nearest decibel, as fractions of decibels are imperceptible.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 2 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
2.0
SITE DESCRIPTION
2.1
The proposed restaurant will be located at Unit 1, The Square, Hale Barns village centre.
2.2
The Square is a mixed use development set adjacent to the Hale Road which is the main road through the village. The Square is on either side of a pedestrianised walkway off the Hale Road, with apartments on the upper floors and commercial units at ground floor level.
2.3
The unit adjoins the stair/lift core for the apartments. We understand that the separating floor between the ground floor unit and the apartments above is of 150mm cast in-situ concrete slab construction overlaid with a floating floor on 200mm timber joists. Such a floor construction can be expected to provide a good level of sound insulation.
2.4
The proposed restaurant will have the main trading area towards the front of the unit; the kitchen, cold room and cellar located adjacent to the stair/lift core; and customer toilets and staff/ancillary areas to the rear.
2.5
The kitchen extract fan will be located in the unit and be ducted to the roof via a dedicated riser. The roof top plant area is at highest part of the building (i.e. higher than any of the apartments).
2.6
The restaurant and back of house air conditioning units, and cold room, cellar and beer chiller units will be ducted to an atmospheric termination in louvres immediately above the rear of the unit.
2.7
The proposals are for the unit to trade until midnight (00:00 hours).
2.8
We understand that the shopfront will be formed of substantial double glazed units (6/12/6mm glazing), with two entrances, one on each of the Hale Road and pedestrian walkway façades. It is proposed that the façade along the pedestrian walkway will be partially openable with outdoor seating available. The proposed layout is shown in Figure 1.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 3 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
3.0
SOUND INSULATION TESTING
3.1
Sound level difference testing was carried out to establish the existing sound separation between the ground floor demise and the apartment immediately above.
3.2
The testing was carried out by generating high levels of pink noise directly below the apartment within the ground floor unit using a sound source and loudspeaker. The resulting source noise levels were measured in the ground floor space along with the transmitted noise levels in the living/dining room and master bedroom of the apartment above. Background noise levels (i.e. the prevailing noise levels in the absence of the transmitted noise) were also measured in the apartment. The measurements were taken as a series of short term third octave band noise measurements.
3.3
The measurements were taken with a B&K 2260 ‘Type 1’ sound analyser (serial no. 02467016). The analyser was check calibrated before and after the measurements with no variance noted.
3.4
Using the results of the measurements, it has been possible to calculate the existing level of sound insulation between the proposed restaurant unit and the apartment above as follows: Table 1: Calculated sound level difference values (dB) Location
3.5
Octave Band Centre Frequency (Hz) 63
125
250
500
1k
2k
4k
Unit 1 to apartment living/dining room
33
44
50
58
62
64
69
Unit 1 to apartment sitting room to rear
33
45
52
60
61
64
69
Unit 1 to apartment bedroom
40
47
54
61
64
66
69
The sound insulation performance values shown in Table 1 are very good and are due to the substantial 150mm solid concrete with floating floor separating floor construction.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 4 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
4.0
BACKGROUND NOISE MEASUREMENTS
4.1
Noise measurements were carried out at two locations on the site representative of the nearest dwellings to the site. The measurement locations are indicated in Figure 1.
4.2
The noise measurements were carried out in late evening/night-time period between 22:00 and 00:15 hours on Tuesday/Wednesday 23/24 February 2016. The noise survey was carried out using a Brüel and Kjær 2260 ‘Type 1’ sound level meter (s/n: 02467016). Calibration checks were carried out both before and after the measurement periods with no variance in levels noted. The noise measurements were taken in ‘free-field’ conditions and at a microphone height of approximately 1.5 m above the ground.
4.3
Weather conditions during the evening survey were cold, clear, dry and calm (<1 m/s).
4.4
The full results of the noise survey are shown in Appendix II and are summarised in Table 2. Table 2: Summary of measured noise levels (dB) Location
LAeq,15 mins
LA90,15 mins
1. Outside apartments facing Hale Road
64 – 68
41 – 52
2. Outside apartments on the pedestrian walkway
58 – 62
39 – 45
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 5 of 17
Cut Restaurants Ltd
5.0
Proposed Restaurant, Unit 1, The Square, Hale Barns
NOISE IMPACT ASSESSMENT & RECOMMENDATIONS Potential Trading Noise Impact
5.1
Planning condition 23 requires details of measures for the control of noise from the premises to the apartments above to be submitted to and approved by the Local Authority. A report (document ref: R1-REP-DS-10-05440-MM-06032014-Planning Condition-F dated 10/06/2014) prepared by Hoare Lea Acoustics on behalf of the Landlord recommended that noise levels in the apartments be controlled to 10 dB lower than the 30dB LAeq criterion for ‘Sleeping’ and the 35dB LAeq criterion for ‘Daytime Resting’, as defined in British Standard 8233: 2014, ‘Guidance on sound insulation and noise reduction for buildings’.
5.2
As such, we have adopted daytime and night-time noise levels of 25 & 20 dB LAeq respectively as the relevant noise limits in respect of trading noise transmitted via the separating floor/ceiling.
5.3
Hepworth Acoustics has carried out numerous noise assessments in connection with proposed restaurants in the past. We understand that the proposed restaurant will feature music at modest background levels only. We have measured the following trading noise levels during busy weekend evening trading periods in similar premises: Table 3: Adopted trading noise levels (dB) Period
Busy evening (Leq)
Email:
[email protected] Tel: 0161 242 7900
Octave Band Centre Frequency (Hz)
A
63
125
250
500
1k
2k
4k
67
72
73
79
79
75
66
82
Report No: P16-083-R01v2 Page 6 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
Noise Transmission within the building 5.4
Using the measured sound level difference values set out in Table 1, we have calculated the following calculated transmitted trading noise levels in the apartment immediately above. Table 4: Calculated worst case transmitted trading noise levels (dB) Location
5.5
Octave Band Centre Frequency (Hz)
A
63
125
250
500
1k
2k
4k
Apartment living/dining room
34
28
23
21
17
11
0
22
Apartment sitting room to rear
34
27
21
19
18
11
0
22
Apartment bedroom
27
25
19
18
15
9
0
20
Table 4 shows that the resulting transmitted noise levels will be between 22 dB and 20 dB LAeq in living areas and the bedroom respectively. These values are within the proposed design criteria for daytime and at night. As such, the existing separating floor construction will provide an adequate level of protection against the transmission of trading noise through the building structure.
5.6
We would nevertheless recommend that all soil vent pipes and/or rainwater pipes that are routed through the premises are wrapped in Rockwool (min. 33kg/m3) and boxed in with at least two layers of 15mm Gyproc SoundBloc plasterboard with well-sealed and staggered joints mounted onto independent timber or metal studs. PA system loudspeakers should be mounted via proprietary antivibration mounts and not rigidly connected to the building structure. Loudspeakers should be orientated downwards and towards the centre of the trading area (i.e. away from the acoustic ceiling and wall linings). Bass bins should not be installed. If higher trading noise levels are desired, an acoustic ceiling will be required throughout the trading area of the demise. Flanking walls would also require treatment. Our recommendations for all trading areas, and those areas open to the trading area (i.e. if there is an open kitchen):
The ceiling should be formed of at least two layers of 15mm Gyproc SoundBloc with staggered and well-sealed joints.
The ceiling should be suspended from proprietary acoustic hangers with a minimum cavity of 150mm with 100mm Rockwool (minimum density 33 kg/m3).
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 7 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
All services must run below the acoustic ceiling and be suspended from appropriate antivibration drop rods.
Penetrations in the ceiling for such drop rods must be oversized just adequately to ensure no direct contact between the rods and boards, and must be well sealed with non-setting mastic. There should be no other penetrations in the ceiling.
Flanking walls and all columns in the trading area should be independently lined with at least two layers of 15mm Gyproc SoundBloc mounted onto independent timber or metal studs with Rockwool (min 33 kg/m3) in the cavity. The timber or metal studs must not be rigidly connected to the building structure - ideally there would be no ties to the existing masonry walls/columns, but if such ties are necessary appropriate resilient wall ties must be used. If necessary, one layer of SoundBloc can be replaced with minimum 15mm plywood to allow fixtures/fittings.
The independent wall/column linings should be installed prior to installation of the acoustic ceiling. Such linings should continue above the height of the acoustic ceiling, which should be installed to form a good seal with the wall/column linings.
As above, PA system loudspeakers should be mounted via proprietary anti-vibration mounts and not rigidly connected to the building structure. Loudspeakers should be orientated downwards and towards the centre of the trading area (i.e. away from the acoustic ceiling and wall linings).
5.7
The proposed acoustic ceiling would reduce noise transmission to the apartments above and allow the following higher trading noise levels in the premises: Table 4: Trading noise levels with acoustic ceiling installed(dB) Period
Higher Trading noise levels (Leq)
Email:
[email protected] Tel: 0161 242 7900
Octave Band Centre Frequency (Hz)
A
63
125
250
500
1k
2k
4k
76
80
84
83
82
78
72
86
Report No: P16-083-R01v2 Page 8 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
Noise break out from the shopfront 5.8
Table 6 below shows the calculated noise level from trading noise break-out through the premises shopfront to outside the bedroom window of the apartment above (i.e. walkway façade elevation). The calculation considers the sound reduction and area of the premise façade and corrections for distance and screening attenuation. Table 6: Calculated trading noise break-out (dB) Location
5.9
Octave Band Centre Frequency (Hz) 63
125
250
500
1k
2k
4k
Outside apartment
36
36
38
34
25
23
5
Lowest measured L90
43
40
39
35
34
27
18
Difference
-7
-4
-1
-1
-9
-4
-13
The calculated noise levels outside the apartment are low. We therefore conclude that there will be no significant impact associated with noise break-out from the premises.
Potential Plant Noise Impact 5.10
Planning condition 22 stipulates that noise arising from any plant or equipment, when measured one metre from the façade of any noise sensitive premises, shall not exceed a rating level of 35 dB (in accordance with BS4142: 1997). The nearest dwellings to the kitchen ventilation plant on the roof top are the apartments on the fourth floor, and the plant louvre at the rear of the premises are the apartments directly above on the first floor.
5.11
The kitchen ventilation fans which will be located within the demise should be fitted with silencers on both inlet and outlet sides before entering the riser. The ducting in the riser should not be rigidly mounted to the riser walls but via appropriate anti-vibration mounts.
5.12
Therefore, consideration should be given to the distance attenuation and likely significant screening attenuation between the rooftop plant and the nearest apartment façade when specifying the equipment.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 9 of 17
Cut Restaurants Ltd
5.13
Proposed Restaurant, Unit 1, The Square, Hale Barns
Careful consideration should be given to the specification of the plant at the louvre to the rear of the premises as the nearest apartment façade is closer to this plant with little distance or screening attenuation. Also the proposed noise limit is the combined noise level from a number of items of plant.
5.1
Typical measures that can be taken to adequately control noise from fixed plant and equipment are as follows:
Specifying low noise equipment;
Careful siting of equipment away from dwellings;
Installation of acoustic enclosures around the fixed plant and machinery where necessary; and
Carrying regular maintenance of equipment to minimise noise emissions.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 10 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
6.0
SUMMARY
6.1
Hepworth Acoustics was commissioned by Cut Restaurants Ltd to assess the potential noise impact of a proposed restaurant to be located in the currently vacant Unit 1 at The Square in Hale Barns. The assessment was requested in connection with noise related conditions of the planning consent for the development which is also part of the landlord’s requirements.
6.2
The assessment has included an inspection of the premises; sound insulation testing between the ground floor and an apartment immediately above; and background noise measurements.
6.3
The sound insulation testing showed that the existing floor provides a good level of sound insulation. As such, trading noise will be controlled to well within the design limits without any specific additional sound insulation measures. We would nevertheless recommend that soil vent pipes and any rainwater pipes are boxed in. If higher trading noise levels are desired this would require additional sound insulation measures such as an acoustic ceiling.
6.4
Noise design limits have been specified for the mechanical services plant as part of the planning consent. Further outline advice has been provided for the control of noise from the mechanical services plant.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 11 of 17
2
1
Email:
[email protected] Tel: 0161 242 7900
Project: P16-083
Figure 1 – Noise Measurement Locations
Title: Figure 1:Noise Measurement Locations
N
Proposed Restaurant, Unit 1, The Square, Hale Barns
X
Key:
- Noise measurement position
Cut Restaurants Ltd
Report No: P16-083-R01v2 Page 12 of 17
Key:
Figure 2 – Proposed Site Layout
Email:
[email protected] Tel: 0161 242 7900
Project: P16-083
Proposed Restaurant, Unit 1, The Square, Hale Barns
Title: Figure 2:Proposed Site Layout
Cut Restaurants Ltd
Report No: P16-083-R01v2 Page 13 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
Appendix I: Noise Units & Indices Sound and the decibel A sound wave is a small fluctuation of atmospheric pressure. The human ear responds to these variations in pressure, producing the sensation of hearing. The ear can detect a very wide range of pressure variations. In order to cope with this wide range of pressure variations, a logarithmic scale is used to convert the values into manageable numbers. Although it might seem unusual to use a logarithmic scale to measure a physical phenomenon, it has been found that human hearing also responds to sound in an approximately logarithmic fashion. The dB (decibel) is the logarithmic unit used to describe sound (or noise) levels. The usual range of sound pressure levels is from 0 dB (threshold of hearing) to 120dB (threshold of pain). Due to the logarithmic nature of decibels, when two noises of the same level are combined together, the total noise level is (under normal circumstances) 3 dB(A) higher than each of the individual noise levels e.g. 60 dB(A) plus 60 dB(A) = 63 dB(A). In terms of perceived ‘loudness’, a 3 dB(A) variation in noise level is a relatively small (but nevertheless just noticeable) change. An increase in noise level of 10 dB(A) generally corresponds to a doubling of perceived loudness. Likewise, a reduction in noise level of 10 dB(A) generally corresponds to a halving of perceived loudness.
Frequency and Hertz (Hz) As well as the loudness of a sound, the frequency content of a sound is also very important. Frequency is a measure of the rate of fluctuation of a sound wave. The unit used is cycles per second, or hertz (Hz). Sometimes large frequency values are written as kiloHertz (kHz), where 1 kHz = 1000 Hz. Young people with normal hearing can hear frequencies in the range 20 Hz to 20 kHz. However, the upper frequency limit gradually reduces as a person gets older.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 14 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
When analysing the frequency content of a sound or noise, the source is often split up into bands with each band covering a specific range of frequencies. A band is said to be an octave band when the uppermost frequency in the band is twice the lowest frequency in the band. Third octave bands are narrower still with three bands covering a doubling in frequency.
A-weighting The ear is not equally sensitive to sound at all frequencies. It is less sensitive to sound at low and very high frequencies, compared with the frequencies in between. Therefore, when measuring a sound made up of different frequencies, it is often useful to ‘weight’ each frequency appropriately, so that the measurement correlates better with what a person would actually hear. This is usually achieved by using an electronic filter called the ‘A’ weighting, which is built into sound level meters. Noise levels measured using the ‘A’ weighting are denoted dB(A) or dBA.
Glossary of Terms When a noise level is constant and does not fluctuate, it can be described adequately by measuring the dB(A) level. However, when the noise level varies with time, the measured dB(A) level will vary as well. In this case it is therefore not possible to represent the noise climate with a simple dB(A) value. In order to describe noise where the level is continuously varying, a number of other indices can be used. The indices used in this report are described below. LAeq
This is the A–weighted 'equivalent continuous noise level' which is an average of the total sound energy measured over a specified time period. In other words, LAeq is the level of a continuous noise which has the same total (A–weighted) energy as the real fluctuating noise, measured over the same time period. It is increasingly being used as the preferred parameter for all forms of environmental noise.
LAmax
This is the maximum A-weighted noise level that was recorded during the monitoring period.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 15 of 17
Cut Restaurants Ltd
LA90
Proposed Restaurant, Unit 1, The Square, Hale Barns
This is the A–weighted noise level exceeded for 90% of the time period. LA90 is used as a measure of background noise.
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 16 of 17
Cut Restaurants Ltd
Proposed Restaurant, Unit 1, The Square, Hale Barns
Appendix II: Noise Survey Results
Date(s):
Late Evening/Night-time – 23/24 February 2016
Equipment:
Bruel & Kjaer 2260 ‘Type 1’ Sound level meter (s/n: 02467016), calibrator, tripod
Weather:
Late Evening/Night-time - Dry, cold and calm
All levels in dB(A) Location 1: Outside Apartments facing Hale Road Time Start
End
Measured Noise Levels (dB) LAmax LAeq LA90
Comments
21:58 22:13
77.5
67.7
52.0
Road traffic
22:31 22:46
78.9
66.9
48.4
Road traffic
23:04 23:19
78.5
65.5
44.4
Road traffic
23:36 23:51
78.0
64.0
41.2
Road traffic
Location 2: Outside Apartments facing Hale Road Time Start
End
Measured Noise Levels (dB) LAmax LAeq LA90
Comments
22:14 22:29
72.7
61.7
45.2
Road traffic
22:48 23:03
72.9
59.6
43.2
Road traffic, faint music break out from Booths
23:20 23:35
71.3
58.0
39.4
Road traffic, faint music break out from Booths
23:51 00:06
71.6
58.0
42.2
Road traffic, faint music break out from Booths
Email:
[email protected] Tel: 0161 242 7900
Report No: P16-083-R01v2 Page 17 of 17
