Planning Statement. Project Prince William School, Oundle. Prepared for Lend Lease

Transcription

1 Planning Statement Project Prince William School, Oundle Prepared for Lend Lease Published 7 September 2015

2 Telephone +44(0) Website London, Birmingham, Manchester, Sudbury Quality Assurance Project Title Document Title Client Client Address Author Checker Report Number Additional information Prince William School, Oundle Planning Statement Lend Lease 20 Triton Street Regent s Place London NW1 3BF Ryan McNulty Jonathan Howson Revision History Revision Date Comments 01 3 September 2015 SRL Technical Services Limited Registered office: Holbrook House, Little Waldingfield, Sudbury, Suffolk, CO10 0TF Registered in England No

3 Summary SRL Technical Services Limited has been commissioned by Lend Lease Consulting (EMEA) Ltd, who are proposing a new school development at Prince William School, Oundle, Northamptonshire. The scheme consists of a New Science Building, and alterations to existing buildings to create a new Music and Drama Block, an updated Sports Centre and 6th Form, and a new Additional Educational Needs area with refurbished staff areas. We have measured typical noise levels around the development, as well as lowest background noise levels during the night. Using this data, we have looked at the potential implications on the ventilation strategy, and set noise limits for plant operating during the day and at night. Noise levels are low enough to facilitate natural ventilation where proposed for all teaching types. The nearest noise sensitive receptors are at St Christopher's Drive to the north, and Herne Road to the south. The noise limits in this report comply with guidance in British Standard 4142:2014. It should be possible to control noise breakout from music teaching areas using enhanced glazing. This will be fully reviewed once details of the existing facade constructions are known. Ryan McNulty Jonathan Howson For and on behalf of SRL Technical Services Limited Tel: rmcnulty@srltsl.com 07/09/2015 Page 3 of 21

4 Contents Summary Introduction Noise Survey External Noise, Noise Break-in and Ventilation Systems Noise Breakout from within the Music Teaching Spaces External Plant Noise Limits Appendix A Appendix B Appendix C /09/2015 Page 4 of 21

5 1.0 Introduction Lend Lease Consulting (EMEA) Ltd are proposing a new school development at Prince William School, Oundle, Northamptonshire The scheme consists of a New Science Building, and alterations to existing buildings to create a new Music and Drama Block, an updated Sports Centre and 6th Form, and a new Additional Educational Needs area with refurbished staff areas. To understand the existing noise climate surrounding the school we measured noise levels on Monday 17 August 2015, and left an automatic sound level meter on site overnight to measure lowest background levels. Our survey data has been used to predict what internal noise levels will be inside classrooms and to help design the building envelope where noise breakout could be an issue (e.g. music classroom breakout noise). We have also set limits at the nearest properties due to new external services plant. The proposals for the scheme are presented in Appendix A (A.8). 07/09/2015 Page 5 of 21

6 2.0 Noise Survey 1.1 Attended Measurements We measured the noise at the site on Monday 17 August 2015 between 13:00 to 14:45 hours, representative of when the school will be in use. Survey details and results are presented in Appendix B. Table 1 provides a summary of the attended measurements. Table 1 - Attended Noise Measurements (17 August 2015) Position Time, hh:mm L Aeq L A90 L Amax A - North of site, representative of north facade of the New Science Block 13: B - South of site, representative of south facade of Sports Hall and 6th Form 13: C - Southwest of site, representative of south facade of AEN area 13: D - Middle of site, representative of south of Music and Drama Block 14: E - Middle of site, representative of north of Music and Drama Block 14: Unattended Measurements To understand lowest background noise levels at the nearest sensitive properties to the scheme, we left an automatic sound level meter in the north of the site. The purpose of this was to set limits for any plant serving the new buildings. Table 2 presents details of the lowest and typical background noise levels measured during the daytime and at night using the automatic logger. 07/09/2015 Page 6 of 21

7 Table 2 - Unattended Noise Measurements (Lowest and Typical Background Levels) Position Period Lowest Background Level, db L A90 Typical Background Level, db L A90 A - Automatic Logger Daytime (during school hours) Night-time (23:00 to 07:00) The nearest noise sensitive properties to the new Science Block are at 25m to the northwest, at St Christopher's Drive. The nearest properties to the AEN & Admin Block, and Sports Hall are approximately 40m away on Herne Road, to the southwest and south, respectively. 2.0 External Noise, Noise Break-in and Ventilation Systems I understand the new Science Block will use mechanical ventilation systems, as will the new music and drama spaces. Elsewhere, I understand the ventilation provision will remain unchanged from the current provision (i.e. natural ventilation where possible). Table 3 provides the BB93 (February 2015) criteria for the teaching areas of the scheme. 07/09/2015 Page 7 of 21

8 Table 3 - Upper Limits for Indoor Ambient Noise Levels Type of Room Indoor Limit for Indoor Ambient Noise Level, L Aeq, 30mins db New Build Refurbished Teaching area intended specifically for students with special hearing and communication needs Classroom, Music Classroom, Music Practice, Control Room, Drama Studio, Group Room Multipurpose Hall Science, Design/Technology/Art/ICT Resource/Library/Study Room Sports Hall, Dance Studio Offices, Staff Room Corridors, stairwells Kitchens 50* 55* Toilets, Cloakrooms 50* 55* * Not mandatory under BB93 During normal midseason weather conditions, BB93 states the above noise levels can increase by 5dB for natural ventilation (NB - not applicable when target is 45dB L Aeq, 30mins ). Any mechanical systems must not exceed the limit in Table 1 above. In summertime, noise levels in naturally ventilated spaces can be up to 55dB L Aeq, 30mins under the control of the teacher, to prevent overheating. This is for the hottest 200 hours of the year. Also during summertime conditions, the limits in Table 1 can be relaxed by 5dB where ventilation is provided mechanically (NB - not applicable when target is 45dB L Aeq, 30mins ). 07/09/2015 Page 8 of 21

9 When an intermittent boost is required for dispersing fumes in practical spaces, the summertime criteria applies over small periods of duration under the direct control of the teacher. Normal conditions for a purely mechanical ventilation system is when the daily average CO 2 concentration is limited to no more than 1,000ppm with the maximum concentration not exceeding 1,500ppm for more than 20 consecutive minutes during normal school operating hours. Normal for a natural or hybrid ventilation system in mode is when the daily average CO 2 concentration is limited to no more than no more than 1,500ppm with the maximum concentration not exceeding 2,000ppm for more than 20 consecutive minutes during normal school operating. The BB93 requirements of Table 3, when including the 5dB relaxation, can be met using open windows, which have an open area no greater than 5% of the floor area of the room under consideration. Facade openings or ventilators can also be used to provide natural ventilation. Noise from mechanical ventilation systems needs to meet the limits in Table 3. Crosstalk attenuators may be required to maintain the sound insulation between rooms if you connect rooms with common ductwork. 3.0 Noise Breakout from within the Music Teaching Spaces Noise breakout from the music rooms of the scheme has potential to disturb other parts of the school. The nearest teaching areas to the new Music and Drama Block are the Maths and existing Science blocks to the West/South. These teaching areas are 5 and 12m from the nearest music teaching spaces, respectively. At a central location representative of the Music and Drama Block, daytime background noise levels were around 41-44dB L A90 during our survey. 07/09/2015 Page 9 of 21

10 Based on preliminary calculations, windows to music and drama rooms must remain closed and enhanced glazing provided to control noise breakout to acceptable levels at the facades of the nearest teaching areas. At this stage, I recommend the project team budget for double glazing with a heavy pane (10 or 12mm), plus a laminated pane (6.4mm or thicker). The specific requirements can be determined once the facade constructions are confirmed. The control of noise breakout from the music areas is not onerous. In most instances, it is likely that internal noise levels will be well below 80dB L Aeq. Higher noise levels require consideration due to their potential to damage hearing and disturb other users of the same building. 07/09/2015 Page 10 of 21

11 4.0 External Plant Noise Limits 4.1 BS 4142:2014 Methods for rating and assessing industrial and commercial sound BS 4142 provides a way of assessing noise from new noise sources against the existing noise climate. The recently updated version of BS 4142 requests that where possible, background sound levels should be measured at the assessment location. The guidance points out that the objective is not simply to ascertain a lowest measured background sound level, but rather to quantify what is typical during particular time periods. BS 4142 defines the noise source which is being assessed as the specific noise. This would be any new external plant items serving the new Science Block or refurbished parts of the School. When comparing the specific noise against existing background levels, BS 4142 highlights that certain acoustic features (tonality, impulsivity, intermittency etc) can increase any significance of impact and penalties should be applied to the specific noise level, in accordance with the guidance in BS4142, to provide the Rating Level of the noise source. As the plant is unknown at this stage it is assumed that the noise has no significant acoustic features. This may need to be reviewed once plant details are known. A comparison of the Rating Level to the background noise level indicates how significant the impact of the new noise source is or will be at the receptor under assessment. If the Rating Level is higher than the background noise level then there may be an 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. 07/09/2015 Page 11 of 21

12 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. 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. The type and location of any external plant is currently unknown. However as the School resides in a quiet part of Northamptonshire, I recommend that plant noise is limited to 5dB below typical background levels during the daytime, and 5dB below lowest background levels at night. Table 5 shows noise limits for plant operating during the daytime. Table 5: Daytime plant noise limits Receptor Source Distance (m) Measured 'typical' background, L A90 Highest permissible plant noise level L Aeq at receptor at 10m from building perimeter St Christopher's Drive Plant serving New Science Block St Christopher's Drive Plant serving Music and Drama Block * Herne Road Plant serving Sports Hall or AEN & Admin Block * Nearest school building is approximately 5m from the proposed plant area. As a result, noise levels of any plant serving this building should be controlled further. This requires development. 07/09/2015 Page 12 of 21

13 Table 6 shows noise limits for plant operating during the night time. Table 6: Night-time plant noise limits Receptor Source Distance (m) Measured 'lowest' background, LA90 Highest permissible plant noise level LAeq (db) at receptor at 10m from building perimeter St Christopher's Drive St Christopher's Drive Herne Road Plant serving New Science Block Plant serving Music and Drama Block Plant serving Sports Hall or AEN & Admin Block /09/2015 Page 13 of 21

14 Appendix A Survey Details A1. Location of Survey Prince William School, Oundle A2. Date & Time of Survey 17/18 August :30 to 11:15 hours A3. Personnel Present During Survey Sam Jones (SRL) A4. Weather Conditions during Survey Dry, calm weather, 70% overcast. Around C during the day and around 8-10 C at night. A5. Instrumentation Norsonic 140 sound level meter (S No: ) Bruel & Kjaer 4231 Calibrator ( S No: ) A6. Calibration Procedure Before and after the survey the measurement apparatus was check calibrated to an accuracy of ±0.3 db using the type 4231 Sound Level Calibrator. The Calibrator produces a sound pressure level of db re 2 x 10-5 Pa at a frequency of 1 khz. A7. Survey Procedure 07/09/2015 Page 14 of 21

15 Ambient noise levels were monitored at various positions around the site as shown on Figure 1. The measurements are tabulated in Appendix B, and explanations of the parameters used are listed in Appendix C. A8. Figure 1 - Proposed Scheme showing Noise Measurement Positions St Christopher's Drive AEN & Admin Block New Science Block Music & Drama Block Sports Hall & 6th Form Herne Road 07/09/2015 Page 15 of 21

16 Appendix B Measured Ambient Noise Levels Position Time L Aeq L A90 L Amax A 13: B 13: C 13: D 14: E 14: /09/2015 Page 16 of 21

17 Logged Noise Levels Position Time L Aeq L A90 A (2015/08/17 13:00:05.00) A (2015/08/17 13:23:30.00) A (2015/08/17 13:27:58.00) A (2015/08/17 13:30:31.00) A (2015/08/17 13:52:14.00) A (2015/08/17 14:10:28.00) A (2015/08/17 14:29:17.00) A (2015/08/17 15:08:02.00) A (2015/08/17 15:30:09.00) A (2015/08/17 15:45:03.00) A (2015/08/17 16:00:03.00) A (2015/08/17 16:15:02.00) A (2015/08/17 16:30:02.00) A (2015/08/17 16:45:02.00) A (2015/08/17 17:00:02.00) A (2015/08/17 17:15:02.00) A (2015/08/17 17:30:02.00) A (2015/08/17 17:45:02.00) A (2015/08/17 18:00:02.00) A (2015/08/17 18:15:02.00) A (2015/08/17 18:30:02.00) A (2015/08/17 18:45:02.00) A (2015/08/17 19:00:02.00) A (2015/08/17 19:15:02.00) A (2015/08/17 19:30:02.00) A (2015/08/17 19:45:02.00) A (2015/08/17 20:00:02.00) A (2015/08/17 20:15:02.00) A (2015/08/17 20:30:02.00) A (2015/08/17 20:45:02.00) /09/2015 Page 17 of 21

18 Position Time L Aeq L A90 A (2015/08/17 21:00:02.00) A (2015/08/17 21:15:02.00) A (2015/08/17 21:30:02.00) A (2015/08/17 21:45:02.00) A (2015/08/17 22:00:02.00) A (2015/08/17 22:15:02.00) A (2015/08/17 22:30:02.00) A (2015/08/17 22:45:02.00) A (2015/08/17 23:00:02.00) A (2015/08/17 23:15:02.00) A (2015/08/17 23:30:02.00) A (2015/08/17 23:45:02.00) A (2015/08/18 00:00:03.00) A (2015/08/18 00:15:02.00) A (2015/08/18 00:30:02.00) A (2015/08/18 00:45:02.00) A (2015/08/18 01:00:02.00) A (2015/08/18 01:15:02.00) A (2015/08/18 01:30:02.00) A (2015/08/18 01:45:02.00) A (2015/08/18 02:00:02.00) A (2015/08/18 02:15:02.00) A (2015/08/18 02:30:02.00) A (2015/08/18 02:45:02.00) A (2015/08/18 03:00:02.00) A (2015/08/18 03:15:02.00) A (2015/08/18 03:30:02.00) A (2015/08/18 03:45:02.00) A (2015/08/18 04:00:02.00) A (2015/08/18 04:15:02.00) A (2015/08/18 04:30:02.00) /09/2015 Page 18 of 21

19 Position Time L Aeq L A90 A (2015/08/18 04:45:02.00) A (2015/08/18 05:00:02.00) A (2015/08/18 05:15:02.00) A (2015/08/18 05:30:02.00) A (2015/08/18 05:45:02.00) A (2015/08/18 06:00:02.00) A (2015/08/18 06:15:02.00) A (2015/08/18 06:30:02.00) A (2015/08/18 06:45:02.00) A (2015/08/18 07:00:02.00) A (2015/08/18 07:15:02.00) A (2015/08/18 07:30:02.00) A (2015/08/18 07:45:02.00) A (2015/08/18 08:00:02.00) A (2015/08/18 08:15:02.00) A (2015/08/18 08:30:02.00) A (2015/08/18 08:45:02.00) A (2015/08/18 09:00:02.00) A (2015/08/18 09:15:02.00) A (2015/08/18 09:30:02.00) A (2015/08/18 09:45:02.00) A (2015/08/18 10:00:02.00) A (2015/08/18 10:15:02.00) A (2015/08/18 10:30:02.00) A (2015/08/18 10:45:02.00) A (2015/08/18 11:00:02.00) /09/2015 Page 19 of 21

20 Appendix C Noise Measurement Parameter Definitions L A90 - The "A" weighted sound pressure level that is exceeded for 90% of the measurement period. It is commonly used as the "Background Noise Level". L Aeq - The "A" weighted equivalent continuous sound pressure level. A representation of a continuous sound level containing the same amount of sound energy as the measured varying noise, over the measurement period. It can be considered as the "average" noise level. 07/09/2015 Page 20 of 21

21 Southern Office & Laboratory Northern Office London Office Holbrook House Lynnfield House 70 Cowcross Street Little Waldingfield Church Street London Sudbury Altrincham EC1M 6EJ Suffolk Cheshire Tel: +44 (0) CO10 0TF WA14 4DZ Tel: +44 (0) Tel: +44 (0) Birmingham Office South Africa Office Cornwall Buildings Ground Floor, Liesbeek House 45 Newhall Street River Park Birmingham Gloucester Road B3 3QR Mowbray Tel: +44 (0) South Africa Tel: +27 (0) Website: SRL offers services in: Acoustics Laboratory and Site Testing Fire BREEAM Air Tightness Air Quality Registered Name and Address: SRL Technical Services Limited Holbrook House Little Waldingfield Sudbury Suffolk CO10 0TF Registered Number: England 07/09/2015 Page 21 of 21