Re: Wildwood, 2-6 High Street, Kingston, KT1 1EY - Proposed Restaurant - External Plant Noise Assessment - Revised

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1 Ref: MDR/J2553b 7 th September 2015 Extracair Installations Ltd Endeavour House Sterte Avenue West Poole Dorset BH15 2AJ For the attention of Mr J Emery Dear Sirs Re: Wildwood, 2-6 High Street, Kingston, KT1 1EY - Proposed Restaurant - External Plant Noise Assessment - Revised Further to your recent instruction, we are pleased to forward a revised external plant noise assessment, incorporating additional background noise data as follows:- Proposed Plant Installation The external plant noise sources are assumed to be located on the rear flat roof area. The external plant noise sources will be the supply air fan and intake, the extract air fan and discharge and 4No. heat pump A/C outdoor units, a normal installation format for Extracair Installations Ltd. We have assumed the plant would be controlled to operate from typically 09.00hrs to no later than 24.00hrs. RandTech Consulting 90 Park Avenue North Northampton NN3 2JD Tel

2 Ref: MDR/J2553b Noise Design Criterion The Royal Borough of Kingston upon Thames planning permission ref: 14/12520/FUL planning condition 4 requires the cumulative external plant noise to be at least 5dBA lower than the existing background noise level, measured or predicted 1m externally to any window at the nearest residential facade. The background noise level is assumed to be a measured LA90 value and the nearest residential windows will be those of the proposed flats on the floors above the restaurant within the same building. The assessment methodology would be to BS4142:2014 and the criteria adopted for the assessment will be to achieve a cumulative plant noise level at least 5dBA below the LA90 background noise level 1m outside the nearest residential windows. During our site inspection visit of 10/2/15 we measured the typical background noise level at the rear of the building on the flat roof area where the external plant will be located and below the windows of the proposed flats on the floors above. The background noise level measured for 1 hour, starting at 11.32hrs was 54dB LA90. This measured background level was a combination of traffic noise in the locality and some existing mechanical plant in operation. Given the enclosed nature of the location it would be reasonable to assume that the measure background noise level would be representative of the background noise level outside the nearest residential windows. Applying planning condition 4 gives a design criterion for the cumulative plant noise of no more than 49dBA 1m outside the nearest residential window. The instrumentation used for the noise measurement was a Casella CEL 63x precision grade real time analyser/sound level meter, serial number , calibration checked before and after using a Casella CEL 110 acoustic calibrator, calibration seen to be correct and unchanged. A copy of the current calibration certificate for the instrument is available upon request. The weather conditions prevailing during the noise measurement were satisfactory with no significant wind and no precipitation. Additional Background Noise Measurement The Royal Borough of Kingston upon Thames requested a further measurement of the prevailing background noise, outside the rear façade windows of the proposed 2 nd floor flats, over a longer time period, to determine a more accurate value for the background noise that would prevail throughout the operational period of the restaurant external plant noise sources. RandTech Consulting 90 Park Avenue North Northampton NN3 2JD Tel

3 Ref: MDR/J2553b An additional noise measurement was undertaken from 15.00hrs 5/10/15 to 15.00hrs 6/10/15, measuring the background LA90 1hr level 1m outside the living room window of Flat 1 on the second floor, directly above the proposed external plant location; please see the attached 2nd floor plan. The instrumentation used was a Rion NL52 precision grade real time analyser/sound level meter, serial number , calibration checked before and after the measurement period and seen to be correct. We attach a copy of the instrument calibration certificate for your reference. The weather conditions prevailing during the measurement period were variable with some periods of rain. The set of 1hour period LA90 values are detailed on an attached graph. For the survey period on 5/10/15 from 15.00hrs up to 23.00hrs there was no significant site construction noise and what was recorded was what could be considered as normal background noise. The average value for this first set of values was 56.2dB and the minimum value was 55.1dB. During the night period the background level decreased slightly and after 07.00hrs on 6/10/15 the background level significantly increased due to construction site activity. In conclusion we would advise that the daytime measurements taken on 5/10/15 are representative of the background level in question. The minimum LA90 level measured was 55.1dB and this compares reasonably with our original measurement of 54.0dB. The External Plant Noise Assessment For the noise assessment design calculations can be undertaken to predict the radiated noise from the two fan systems and 4No. heat pump outdoor units operating at maximum noise output, radiating noise within a reverberant location to a distance of 6m. Where required mitigation is required this is included within the plant noise assessment. The Calculated External Plant Noise We have attached standard design calculations on three design sheets, to predict the radiated noise at 6m distance. For simplicity we have assumed no acoustic screen enclosing the plant and all the plant sources are at 6m distance; source within the flat roof area are assumed to be in a reverberant location. The 4No. Toshiba RAV-SP1104AT-E heat pump outdoor units would create a maximum noise level of 46dBA at 6m distance. RandTech Consulting 90 Park Avenue North Northampton NN3 2JD Tel

4 Ref: MDR/J2553b The supply air ventilation system based on a Nicotra 9-9 external fan in an acoustic box with a connecting duct to an intake louvre The silenced noise level would be 37dBA at 6m distance, from the air intake louvre, and fitted with a 1200mm long rectangular splitter silencer, 38% free area design. The extract air ventilation system based on a Systemair MUB 630 DV4-K2 external fan in an acoustic box with connecting ductwork to a vertical discharge, on the discharge side of the fan a rectangular silencer would be fitted, typically a 44% free area splitter design, 1800mm long located in the ductwork. The silenced noise level would be 36dBA at 6m distance, assuming free-field spherical radiation. In addition there would be some fan casing break-out noise requiring acoustic cladding to be applied to the fan casing and a short length of connecting ductwork. Typically an acoustic cladding nominally 10kg/m2, (1.2mm sheet mild steel and 50mm mineral wool insulation), would reduce the break-out noise to 26dBA at 6m. In addition to reduce fan break-out noise from the inlet side ductwork will require an inlet silencer to be fitted, typically a 44% free area splitter design, 900mm long, reducing inlet ductwork break-out to 32dBA at 6m. The summated noise level of all the external plant in operation at a distance of 6m, typically outside the nearest flat window would be 47dBA, which would be 7dBA less than the measured background noise level 54dB LA90 1hr assumed to be outside the nearest residential windows. For the purposes of BS4142:2014, the plant rating level would be 47dBA, with no tonal correction required for the silenced noise sources, the background level for comparison is 54dB LA90 1hr, and the rating level has been calculated to be 7dBA less than the background level. Please see the attached design sheets and supporting information. Conclusion The initial noise assessment for the proposed external plant to be located at the rear of the building predicts a very reasonable operating noise level at typically 6m distance, assumed to be the distance from the plant location to the nearest residential windows. This complies with planning condition 4. The subsequent background noise measurements taken outside the living room window of Flat 1 on the 2nd floor over a 24 hour period have confirmed the original background noise level of 54.0dB as being valid for the original noise assement. RandTech Consulting 90 Park Avenue North Northampton NN3 2JD Tel

5 Ref: MDR/J2553b We trust the revised noise assessment meets with your approval and we remain. Yours faithfully M D Randall BSc(Eng) CEng MCIBSE MIOA RandTech Consulting 90 Park Avenue North Northampton NN3 2JD Tel

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