115 NEW CAVENDISH STREET 5 TH FLOOR EXTENSION

Transcription

1 115 NEW CAVENDISH STREET 5 TH FLOOR EXTENSION Acoustic Design Report University of Westminster 11 August 2009

2 QM Issue/revision Issue 1 Issue 2 Remarks Draft - Date 07 August August 2007 Prepared by Signature Martin Raisborough Martin Raisborough Checked by David Maundrill David Maundrill Signature Authorised by David Maundrill David Maundrill Signature Project number File reference ADR1 ADR1.1 WSP Acoustics WSP House 70 Chancery Lane London WC2A 1AF Tel: +44 (0) Fax: +44 (0)

3 Contents 1 Introduction 1 2 Environmental Noise Monitoring 2 3 External Building Fabric Assessment 3 Internal Noise Criterion 3 External NoIse Data For Assessment 3 External Building Fabric Assessment Details 4 Sound Insulation Performance for Roof 5 4 Internal Building Services Plant Noise Control 6 Internal M+E Noise Criteria 6 Ductborne Noise Control 6 System Generated Noise 8 5 External Building Services Plant Noise Control 10 Plant Noise Emission Limits 10 Assessment of Atmospheric Plant Noise Emissions 12 6 Internal Building Fabric Acoustics 14 West Stair Core Areas 14 Glazed Partition Between Library & Computer Space 14 Partition between Disabled Toilet and Computer Space 15 Comms Room Partitions 15 Risers. 16 Door D-507 (Entrance to Computer Space from Lobby) 17 Partitions between Breakout/Discussion Areas and Circulation Space 17 Partitions between Breakout/Discussion Areas and Circulation Space 18 Partition between Services Riser and Discussion Area 18 External Door to Plant Area 19 Acoustic Treatment to RWP s 19 7 Control of Reverberation 20 Reverberation Time Criteria 20 Reverberation within Library Areas 20 Reverberation within Discussion & Breakout Areas 20 Reverberation within Stair Cores & Circulation Areas 21 Appendix A Glossary of Acoustic Terminology 22 Appendix B Site Plan 24 Appendix C Noise Measurement Results 25

4 Appendix D External Building Fabric Performance Specifications 29 Appendix E Attenuator Schedule 30 Appendix F Ceiling & Floor Void Barrier General Detailing 31 Appendix G Report Limitations 34

5 1 Introduction 1.1 WSP Acoustics has been commissioned by University of Westminster to undertake acoustic consultancy services in relation to the proposed 5 th floor roof extension project at University of Westminster s New Cavendish Street campus. 1.2 It is proposed to add an additional storey height onto the existing building to accommodate an extension to the existing library on the 4 th floor. 1.3 Acoustic consultancy services are required in order to ensure the acoustic integrity of the new library extension. 1.4 This report employs technical acoustic terminology. A glossary of acoustic terminology employed in this report is presented in Appendix A. University of Westminster ADR1.1 1

6 2 Environmental Noise Monitoring 2.1 An environmental noise survey was undertaken at 5 th floor level overlooking New Cavendish Street over a typical 24 hour weekday period to establish the prevailing noise levels at this location due to road traffic movements and other environmental noise sources. 2.2 The environmental noise survey commenced at approximately 15:30 hours on Wednesday 5 th August and concluded at approximately 15:30 hours on Thursday 6 th August The details of the measurement equipment used during the noise survey are presented in Table 1 below: Table 1 Equipment Details Equipment Description Manufacturer & Type No. Serial No. Sound Level Meter 01dB-METRAVIB Blue Solo Pre-amplifier 01dB-MATRAVIB PRE 21 S Microphone 01dB MCE Calibrator Brüel & Kjær The sound level meter was fitted with a windshield during the survey and was calibrated prior to and upon completion of the survey. No calibration drifts were found to have occurred. 2.5 The prevailing L Aeq L Amax, fast, L A10 and L A90 noise levels were measured. In addition, octave band ( Hz) spectral levels were also recorded. 2.6 The microphone of the sound level meter was mounted at the parapet edge of the 5 th floor roof overlooking New Cavendish Street, approximately 2 metres from roof level and in free field conditions. The approximate measurement positions are indicated on the site plan in Appendix B. 2.7 Weather conditions throughout the survey were considered to be suitable for noise monitoring, it being dry with only a light breeze. 2.8 Noise sources at the measurement position were noted to be mainly due to road traffic movements along New Cavendish Street and surrounding roads. No noise from building services plant serving the University of Westminster buildings was noted at the measurement position. 2.9 The detailed results of the noise survey are presented in survey results are presented in the Table in Appendix C, with a summary presented in Table 2 below. Table 2 Summary of Results from Noise Measurement Survey Period Measured Noise Levels (db) L Aeq, T Range of L Amax, fast L A10, T L A90, T Daytime (07:00 to 23:00) 63.1dB 73.1 to dB 56.1dB Night time (23:00 to 07:00) 56.8dB 68.5 to dB 50.6dB University of Westminster ADR1.1 2

7 3 External Building Fabric Assessment 3.1 Based upon the noise data measured during the environmental noise survey, an assessment may be undertaken to predict the levels of external noise intrusion into the library spaces at 5 th floor level. 3.2 The sound insulation performance requirements for the external façade are dependent predominately upon the external ambient noise climate and the internal noise criterion within the library spaces at 5 th floor level. INTERNAL NOISE CRITERION 3.3 With regards to the internal noise criterion, there are no statutory requirements for this type of accommodation. Despite this, however, it is recommended that guidance is taken from the DfES document Building Bulletin 93 (BB93) Acoustic Design of Schools which forms Requirement E4 of Approved Document E of the Building Regulations It is considered that this standard is the most applicable for this further education establishment. 3.4 In light of the above, BB93 recommends an internal noise level of 35dB L Aeq, 30 minutes for quiet study areas of libraries. This criterion is applicable to the combination of all noise within the library space (i.e. external noise intrusion and mechanical services noise), although excludes activity noise associated with the use of the library itself. 3.5 It is recommended, therefore, that noise due to external noise intrusion does not exceed a level of 33dB L Aeq, in order to allow for any increases in noise due to the operation of building services plant within the library areas. EXTERNAL NOISE DATA FOR ASSESSMENT 3.6 With regards to the external noise data measured during the environmental noise survey, it can be seen from the graph in Appendix C that there were two periods where the L Aeq, 30 minute measured noise level was clearly a-typical of the otherwise measured background noise climate, namely between 21:30 and 22:00 hours on Wednesday 5 th August and between 14:30 and 15:00 hours on Thursday 6 th August. Given that these periods are considered a-typical, it is not considered appropriate to use data from these periods to assess the sound insulation performance requirements for the external façade. 3.7 In light of the above, the next highest L Aeq, 30 minute period was that measured between 13:00 and 13:30 hours on Thursday 6 th August with a level of 65dBA. This level is considered appropriate for use in assessing the sound insulation performance requirements for the external façade. 3.8 During the measurement survey, data was also recorded in terms of octave band sound pressure levels ( Hz). This data is required in order to assess the University of Westminster ADR1.1 3

8 sound insulation performance requirements for the external façade and to produce acoustic performance specifications. 3.9 Based on the above, the noise measurement data in Table 3 below will be used for the external building fabric assessment. Table 3 Noise levels to be used in External Building Fabric Assessment Parameter Noise Assessment Data (db re 20x10-6 Octave Band Centre Frequency (Hz) k 2k 4k 8k dba Daytime L eq,30 minutes (13:00 13:30) EXTERNAL BUILDING FABRIC ASSESSMENT DETAILS 3.10 The Darnton EGS drawings issued by to WSP Acoustics on Wednesday 5 th August 2009 have been used in this assessment to predict external noise intrusion into the library areas Based upon the results of our assessments, the minimum sound insulation performance requirements for the composite external façade are detailed in the specification in Appendix D. This specification is suitable for issue to nominated tenderers It is important to note that the sound insulation performance specification in Appendix D is applicable to the acoustic performance of the composite façade as a whole, including glazing, framing, spandrel panels, openings, etc In order that the sound insulation performance specification in Appendix D may be achieved, it is considered appropriate to offer design guidance in terms of likely constructions required With regards to the glazing units, and following our discussions with Mark Baggoley of Darnton EGS, it is understood that glazing systems are to be triple glazed within wood frames. The glazing units are to be 4mm glass / 16mm airspace / 4mm glass / 16mm airspace / 4mm glass. We do not hold any library acoustic data for this type of construction. It is anticipated, however, that this glazing configuration will achieve a performance of at least 38dB R w. This acoustic performance is likely to be adequate in maintaining the composite sound insulation performance requirement for the façade presented in Appendix D With regards to the non glazed elements of the façade, it is understood that a cladding panel is proposed with an internal plyboard lining. This performance is likely to provide a sound insulation performance of around 35dB R w. This performance is unlikely to be sufficient in maintaining the composite sound insulation performance specification in Appendix D. Accordingly, it is recommended that consideration be given to introducing 50mm mineral fibre (20-30 kg/m 3 ) to the cavity in order that the sound insulation performance may be increased. Assuming the mineral fibre insulation within the cavity a sound insulation performance of around 42dB R w is predicted, which is considered University of Westminster ADR1.1 4

9 sufficient in maintaining the composite sound insulation performance specification in Appendix D Notwithstanding the above, however, it should be stressed that the above guidance is provided purely for costing/guidance purposes only, and does not constitute recommendations in terms of façade composition. It should be ultimately ensured that the Sound Reduction Indices (SRI s) recommended in Appendix D are achieved for the composite façade system The suppliers/manufacturers of the façade system(s) should confirm the sound insulation performance specifications of their proposed system(s) for comparison with the specified acoustic performance in Appendix D If there is any doubt as to the ability of the proposed façade system(s) to conform to the acoustic specifications in Appendix D, it may be necessary to undertake sound insulation testing in accordance with BS EN ISO 140-3:1995 Laboratory measurement of airborne sound insulation of building elements in a certified acoustic test facility. SOUND INSULATION PERFORMANCE FOR ROOF 3.19 In order that external noise may be adequately controlled within the internal areas of the 5 th floor extension, it is recommended that the roof structure provides a minimum sound insulation performance of 35dB R w From our discussions with Mark Baggoley of Darnton EGS, it is understood that the roof is to be of the following nominal construction: Gravel/Paving slabs to external 110mm insulation Waterproofing membrane 20mm plyboard to internal 3.21 It is considered that the above construction is capable of achieving a sound insulation performance of 35dB R w depending upon the density of the 110mm insulation layer. The suppliers/installers of the roofing system should be required to demonstrate that the proposed roof system is capable of complying with the recommended 35dB R w specification, as tested in accordance with BS EN ISO 140-3:1995 Laboratory measurement of airborne sound insulation of building elements University of Westminster ADR1.1 5

10 4 Internal Building Services Plant Noise Control INTERNAL M+E NOISE CRITERIA 4.1 In order that noise associated with the operation of mechanical services within the various internal spaces of the 5 th floor extension does not create an adverse impact due to noise, it is recommended that the design standards within the DfES document Building Bulletin 93 (BB93) Acoustic Design of Schools are complied with. As previously discussed for external noise intrusion, it is considered that the criteria within this standard are the most applicable for this further education establishment. 4.2 With regards to the main library areas BB93 recommends an internal ambient noise level of 35dB L Aeq, 30 minutes. As previously described, this level includes for the combination of noise from external noise intrusion and that of building services plant. As such, it is recommended that noise associated with the operation of building services plant does not exceed a level of 33dB L Aeq, in order to allow for any increases in noise due to external noise intrusion within the library areas. Based on the guidance within BS 8233, this 33dBA criterion can be compared to an NR level of Based on the above assumptions for internal mechanical services noise, Table 4 presents the recommended internal noise criteria for mechanical services systems for the various proposed spaces. Table 4 Recommended Internal Mechanical Services Noise Criteria Internal Space Mechanical Services Noise Criterion L Aeq, 30 minutes (db) NR (for guidance) Quiet working library space 33dBA NR27 Computer work stations space 38dBA NR32 Breakout space 38dBA NR32 Discussion area 38dBA NR32 Disabled Toilet 48dBA NR42 Lobby s / Circulation / Stairwells 43dBA NR37 DUCTBORNE NOISE CONTROL 4.4 It is understood that one supply and extract air handling units is proposed to serve the 5 th floor library spaces, and is to be located on the plant area at the eastern end of the roof. The quoted noise data for the roomside paths of this unit are quoted in Table 5 below. This data has been taken from the ECE UK Ltd. quote dated 29 July 200 Table 5 Manufacturer s Noise Data for AHU Roomside Paths In-duct Sound Power Levels (db Re 1x10-12 Watts) Octave Band Centre Frequency (Hz) k 2k 4k 8k Supply Extract University of Westminster ADR1.1 6

11 4.5 Based on the above AHU data, we have undertaken assessment of the attenuation requirements for the Roomside paths of the AHU in order that internal; noise levels within the various internal spaces may be in accordance with the recommended criteria in Table 4. Our assessments have considered the WSP UK ventilation layout drawing M (Rev.T2) dated July The recommended specifications for supply and extract attenuators are presented in the schedule in Appendix E. 4.7 It is essential that all silencers are manufactured in accordance with our "Specification for Noise and Vibration Control Products" which is appended to this report. This will ensure that all silencers are mechanically and aerodynamically suitable. 4.8 The dimensions in the schedule are nominal for the type of silencers indicated by the insertion loss and aerodynamic data. The pressure drop figures are typical for the silencer cross sections and airflows indicated. Some variation in dimensions and pressure drop may be allowable dependant upon the particular splitter arrangement used. Ideally, silencers having high pressure drops should be avoided. 4.9 It is recommended that the attenuators are located as close to the fan unit as possible, and that the interconnecting ductwork between the fan spigot connection and the attenuator is acoustically lagged with 10kg/m 2 sound barrier matt, such as that manufactured by Siderise The other important factor to be considered is the pressure drop (and associated regenerated noise) that can result if silencers are located too close to bends. To avoid problems with regenerated noise and excessive pressure drop, silencers should ideally be located at least two maximum duct dimensions from any bends. It is particularly important that silencer discharges be kept away from vaned bends, as the high passage velocities in the silencer can generate high noise levels if directed onto turning vanes In addition to the above ductborne noise may still compromise the internal and external noise criteria if duct velocities are not adequately considered. To this end, the maximum velocities in Table 6 are recommended. Table 6 Recommended Maximum Air Velocities CRITERION NR Riser Main Branch Grille Diffuser Extract stub ducts (above ceiling) University of Westminster ADR1.1 7

12 SYSTEM GENERATED NOISE 4.12 It may be assumed that after completion of a detailed acoustic analysis and silencer selection, at the roomside end of the duct silencer the service is effectively silenced with respect to the design noise criterion. It follows therefore that providing no further significant noise is generated between the silencer and the critical space, the acoustic design criterion will be achieved. However, even without the presence of additional air movers in the intervening section of ductwork, it is still possible to generate sufficient noise such that the terminal noise level exceeds the design criteria Noise may be regenerated at any ductwork discontinuity, bends, take offs, dampers, etc., as well as at any terminal device itself. This regenerated noise manifests itself in the controlled space in the following manner:- as break-out noise radiation from the walls of the ductwork; as excessive noise radiation from the ductwork terminal to the conditioned space The general parameters for ductwork or pipework design, fabrication and installation are laid down in relevant Codes of Practice (HVCA and CIBSE). However, in order to alleviate the most commonly occurring problems with duct services, the following items represent a list of good acoustic practice:- Bends and bifurcations - 90 bends should be either of the radiused type, or be fitted with equally spaced short chord turning vanes. All branches should be fitted with boots or coned as standard practice. Transitions are to be as gradual as possible within the physical limitations and it is preferred that one pair of sides remain parallel. Duct velocities should be limited to those specified in the attached Table 6. The aspect ratios in all main and branch duct runs for rectangular (or flat oval) ductwork should ideally not exceed 3:1. It is recommended that ductwork having an aspect ratio of between 3:1 and 5:1 is stiffened by the use of heavier gauge sheet steel. Ductwork with an aspect ratio greater than 5:1 must be acoustically lagged in accordance with the guidance in Paragraph Control dampers used near duct terminations should only be used to provide fine trimming of the airflow, otherwise the resulting turbulence will cause excessive noise at the ductwork terminals and possibly via the ductwork walls. If dampers are likely to be used beyond fine trimming purposes, we recommend that 'damper silencers' are fitted between the dampers and the duct terminals. A typical damper silencer would be 45% free area, 600 mm long and of suitable cross section to limit the face velocity to that specified in Table 6. The maximum damper face velocity should be limited similarly It is unlikely that piped services associated with the various M&E plant items will produce any flow regenerated noise problems. A worthwhile precaution, however, University of Westminster ADR1.1 8

13 would be to keep the friction losses to below 280 Pa/m for pipes between 12 and 75 mm in diameter We strongly warn against the use of manufacturers simplified NR or db(a) figures for AHU s and terminal units as these are often calculated assuming an unrealistic acoustic environment (such as one unit in a large open plan, acoustically 'soft' office), and consequently can be very optimistic. University of Westminster ADR1.1 9

14 5 External Building Services Plant Noise Control PLANT NOISE EMISSION LIMITS 5.1 Noise emissions associated with the operation of future items of building services plant installed as part of the 5 th floor extension project should be suitably controlled in order to minimise the impact upon the nearby noise sensitive residential properties. In addition, the impact of noise due to atmospheric plant noise emissions upon the nearby commercial premises should also be considered, including the University of Westminster building itself. 5.2 It is noted that the façade of the eastern end of the university building extends several stories higher than the proposed 5 th floor plant area. This is indicated in Figure 1 below. It is likely that this will be the most onerous receptor in terms of controlling atmospheric noise emissions from building services plant. Figure 1 Proposed Plant Area on 5 th Floor 5.3 Residential receptors that are likely to be worst affected by noise from building services plant on the 5 th floor plant area are those along Cleveland Street and can be seen in the distance in Figure Other residential receptors in the near vicinity to the site are located on the opposite site of New Cavendish Street (south side) to the site and to the west of the site, along Hanson Street. These are shown in Figure 2. It is not considered that these receptors will be affected by noise from building services plant proposed for the 5 th floor plant area shown in Figure 1 due to the screening that will be provided by the building extension itself. University of Westminster ADR1.1 10

15 5.5 If, however, further items of plant are proposed on the roof of the 5 th floor extension, or other areas of the roof, these receptors could be affected by noise from future items of building services plant. Figure 2 Residential Receptors along New Cavendish Street (south side) Residential Receptor along New Cavendish Street (south side) Residential Receptors along Hanson Street 5.6 The extent of the noise control measures for the proposed items of plant will depend upon a number of factors, including (but not limited to) the noise emission requirements of the Local Authority, the existing prevailing daytime and night time noise levels and the number and type of plant items & their noise characteristics. 5.7 Since the details of the proposed plant scheme are not known at this stage, it is appropriate to set noise emission limits that are applicable to the total noise from all new items of building services plant associated with this project. 5.8 In accordance with the standard requirements of Westminster City Council, it is recommended that the rating noise level associated with the simultaneous operation of all building services plant, operating at worst case duty, achieves a level 10dBA below the otherwise prevailing L A90 background noise level at 1m from the façade of the worst affected residential receptor. The noise impact upon these receptors should be assessed in accordance with BS 4142:1997 Method for rating noise affecting mixed residential and industrial areas 5.9 In addition to the above, and with regards to the impact of noise upon the façade of the University of Westminster building immediately adjacent to the proposed 5 th floor plant area (as shown in Figure 1), it is recommended that the L Aeq, 1 hour noise level at 1 metre from the façade of this receptor does not exceed 55dBA. This level is based on an assumed inside to outside sound level difference of 15dBAfor a partially open window 1, which would result in an internal noise level of 40dBA within the Westminster University building. An internal noise level of 40dBA is that quoted in BB93 for typical classrooms. 1 As quoted in PPG24. University of Westminster ADR1.1 11

16 5.10 Based on the above, and in order to specify quantitative noise emission limits for the residential receptors, it is necessary to determine the typically lowest L A90 noise level measured during the environmental noise survey. During the daytime (07:00 to 23:00 hours) the lowest L A90, 30 minute noise level was measured to be 52dBA. During the night time (23:00 to 07:00 hours), the lowest L A90, 30 minute noise level was measured to be 50dBA From this, noise emission limits for proposed external plant items may be specified. The recommended noise emission limits for building services plant items serving the proposed 5 th floor extension are presented in Table 7. Table 7 Building Services Plant Noise Emission Limits Receptor Location Period, T Rating Noise Emission Limit 1 metre from the façade of Residential Receptors (free field level) Day (07:00 20:00) Night (23:00 07:00) 42 db L Ar, 1 hour 40 db L Ar, 5 minutes 1 metre from the façade of Commercial Receptors (free field level) 24 hours 55 db L Ar, 1 hour 5.12 It should be noted that the above noise emission limits are applicable to the total noise from the simultaneous operation of all new building services plant associated with the 5 th floor extension project. As such, noise emissions from individual items of plant will need to be lower than the limits detailed in the table above, although the exact limit for each individual item of plant will be dependant upon its type, noise characteristics, location etc Assessments of plant noise emissions should be undertaken in accordance with the methodology in BS 4142:1997 including +5dBA rating corrections for tonal or intermittent plant where applicable. ASSESSMENT OF ATMOSPHERIC PLANT NOISE EMISSIONS 5.14 The noise data for the air handling unit does not include for levels at the atmospheric spigot connections. As such, we are unable to undertake accurate calculations with regards to atmospheric noise emissions from this plant. It is considered reasonable to assume, however, that atmospheric noise at the fresh air inlet and discharge spigot connections will be in line with those at the roomside extract path quoted in Table Based on this data, the recommended specifications for fresh air inlet and discharge attenuators in order that the atmospheric noise criteria in Table 7 may be achieved are presented in the attenuator schedule in Appendix E It is essential that all silencers are manufactured in accordance with our "Specification for Noise and Vibration Control Products" which is appended to this report. This will ensure that all silencers are mechanically and aerodynamically suitable With regards to the 2 no. condenser units it is understood that these are rated at 64dBA (larger unit) and 60dBA (smaller unit) respectively. The distance and University of Westminster ADR1.1 12

17 environmental conditions within which this data relates is not known, although at this stage it is assumed that this data is at 1 metre distance from each unit and in free field conditions over a reflective plane. It is understood that both these units are to be inverter driven. As such, it is not considered that the BS dB rating correction will be required for these units as the fans will be duty controlled It is noted that both the condenser units are circa 6 metres from the Westminster University building façade. Based on this, and assuming line source attenuation (3dB per doubling of distance), a noise level of 56dBA for the larger unit and 52dBA for the smaller unit is predicted at the façade of the Westminster University building (free field levels) Considering the total noise from the AHU atmospheric noise paths and the two condenser units, Table 8 presents the total noise level predicted at the various noise sensitive receptors. Table 8 Predicted Building Services Plant Noise Levels Plant Item Receptor Location Worst affected Residential Dwelling (New Cavendish Street) Westminster University Façade AHU Fresh Air Intake 15dB L Ar, T 45dB L Ar, T AHU Discharge 15dB L Ar, T 45dB L Ar, T Large Condenser 28dB L Ar, T 56dB L Ar, T Small Condenser 24dB L Ar, T 52dB L Ar, T TOTAL 30dB L Ar, T 58dB L Ar, T 5.20 In comparing the predicted plant noise emissions in Table 8 with the noise emission criteria in Table 7, it can be seen that plant noise emissions at the worst affected residential receptor are comfortably below both the daytime and night time noise emission criteria of Westminster City Council. With regards to the noise impact upon the façade of Westminster University, however, a 3dB exceedance of the recommended 55dB L Ar, T criterion is predicted. This exceedance is due to the operation of the 2 no. condenser units In light of the above, it is recommended that either a) dialogue is entered into with Westminster University with regards to the acceptability of this exceedance of the recommended 55dB L Ar, T noise emission limit, or b) attenuation options are discussed with the manufacturers of the condenser units in order that noise levels may be reduced From our discussions with WSP mechanical services engineers, it is considered likely that the compressors of the condenser units may be fitted with acoustic jackets which will reduce noise. It is recommended that this option be investigated in the first instance. University of Westminster ADR1.1 13

18 6 Internal Building Fabric Acoustics WEST STAIR CORE AREAS 6.1 The separating wall between the west stair core (including the riser) to the quiet working library space is proposed to be of a drywall construction in line with the following construction: 70mm metal stud frame at 600mm centres 2x layers 15mm Gyproc SoundBloc each side Cavity to be fitted with 50mm mineral fibre insulation 6.2 This construction is expected to provide a sound insulation performance of 56dB R w. This performance is considered suitable in controlling noise transfer from the stair core within the quiet working library space. 6.3 The partition should extend from the structural slab and continue uninterrupted through the raised floor and be adequately sealed to the underside of the structural roof. If the roof is to be of a profiled detail, adequate detailing should be employed in order to maintain acoustic integrity at this junction. 6.4 It is recommended that the lobby doors between the stair core and the quiet working library space should each achieve a minimum sound insulation performance of 30dB R w. GLAZED PARTITION BETWEEN LIBRARY & COMPUTER SPACE 6.5 It is recommended that the glazed partition separating the quiet working library space and the computer work stations space achieves a minimum in-situ airborne sound insulation performance of 35dB D nt,w. 6.6 In order that this performance may be achieved, it is recommended that the main glazed partition provides a minimum laboratory airborne sound insulation performance of 40dB R w. This performance is considered to be typically achievable by either of the following double glazing constructions: 10mm/12mm/13.8mm (laminate) 10mm/16mm/8.8mm (laminate) 6.7 The glazed partition is to extend from the raised floor to the underside of the suspended metal pan ceiling system. In order to maintain the 35dB D nt, w performance, therefore, ceiling and floor void barriers will be required above and below the partition. 6.8 The ability of the in-situ installation to achieve the 35dB D nt, w performance is very much dependent upon the quality of workmanship of the void barrier installation. The void barrier material should achieve a minimum sound insulation performance of 30dB R w and 45dB D nc, w. A proprietary product with a lead core is recommended as it is University of Westminster ADR1.1 14

19 easier to cut around building services systems than mineral fibre based barriers. Suitable proprietary products are; Soundstop CB10 Acoustic Curtain (Soundstop 10) Sound Reduction Systems Lamaphon CBX Flexible Acoustic Ceiling Void Barrier (CB10) Siderise 6.9 Detailed recommendations with regards to void barrier detailing are presented in Appendix F With regards to the door within this partition separating the two spaces, it is recommended that this door achieves a minimum sound insulation performance of 32dB R w. It is unlikely that this performance is achievable with a double swing door as good acoustic seals will be required for the head, jambs and threshold The suspended ceiling proposed for the library areas is the Armstrong Oracle metal pan system. In terms of sound insulation of this ceiling system, a performance of 40dB D nc, w is quoted by the manufacturers. This performance is considered adequate in maintaining the proposed 35dB D nt, w performance due to flanking sound transmission along the suspended ceiling system. PARTITION BETWEEN DISABLED TOILET AND COMPUTER SPACE 6.12 It is recommended that the sound insulation performance of the partition between the disabled toilet and the computer workstation space achieves a minimum insitu sound insulation performance of 48dB D nt, w. In order that this performance may be achieved, the partition should achieve a minimum laboratory sound insulation performance of 56dB R w This performance is typically achievable by the construction detailed in Paragraph 6.1. The partition should extend from the structural slab and continue uninterrupted through the raised floor and suspended ceiling and be adequately sealed to the underside of the structural roof Notwithstanding the above, it is understood that this partition with is too wide to fit the junction with the external façade due to the narrow glazing centres. As such, it is recommended that a solid timber mullion is installed at the junction of the façade and that the partition is connected to this timber mullion. The timber mullion should be hardwood and should achieve a minimum thickness of 48mm. The mullion should be as short a length as possible in order to allow the free opening of external windows. COMMS ROOM PARTITIONS 6.15 In order that noise associated with the operation of IT equipment within the comms room may be adequately controlled within the computer workstation space, it is recommended that the partition achieves a minimum in-situ performance of 38dB D nt, w In order that this performance may be achieved, it is recommended that the main partition achieves a minimum sound insulation performance of 47dB R w. A typical construction capable of achieving this performance is presented below: University of Westminster ADR1.1 15

20 70mm metal stud frame at 600mm centres 1x layer 15mm Gyproc SoundBloc each side Cavity to be fitted with 25mm mineral fibre insulation 6.17 This partition is to extend from the raised floor to the underside of the suspended ceiling system. As such, ceiling and floor void barriers are required in order that the acoustic integrity of this partition may be maintained The ability of the in-situ installation to achieve the 38dB D nt, w performance is very much dependent upon the quality of workmanship of the void barrier installation. The void barrier material should achieve a minimum sound insulation performance of 30dB R w and 45dB D nc, w. A proprietary product with a lead core is recommended as it is easier to cut around building services systems than mineral fibre based barriers. Suitable proprietary products are; Soundstop CB10 Acoustic Curtain (Soundstop 10) Sound Reduction Systems Lamaphon CBX Flexible Acoustic Ceiling Void Barrier (CB10) Siderise 6.19 Detailed recommendations with regards to void barrier detailing are presented in Appendix F The entrance doorset to the comms room should achieve a minimum sound insulation performance of 35dB R w in order that the in situ performance of 38dB D nt, w may be maintained by the composite partition. RISERS Walls forming risers are proposed to be of a drywall construction in line with the following: 70mm metal stud frame at 600mm centres 2x layers 15mm Gyproc SoundBloc each side Cavity to be fitted with 50mm mineral fibre insulation 6.22 This construction is expected to provide a sound insulation performance of 56dB R w. This performance is considered suitable in controlling noise breakout from the risers to the adjacent spaces The partition should extend from the structural slab and continue uninterrupted through the raised floor and be adequately sealed to the underside of the structural roof. If the roof is to be of a profiled detail, adequate detailing should be employed in order to maintain acoustic integrity at this junction It is recommended that all doorsets providing access to the risers achieve a minimum sound insulation performance of 30dB R w. University of Westminster ADR1.1 16

21 DOOR D-507 (ENTRANCE TO COMPUTER SPACE FROM LOBBY) 6.25 In order that noise associated with activities in the lobby may be adequately controlled within the computer work stations space, it is recommended that this doorset achieves a minimum sound insulation performance of 35dB R w In order that this acoustic performance may be achieved, good quality acoustic seals will be required to the head, jambs and threshold. PARTITIONS BETWEEN BREAKOUT/DISCUSSION AREAS AND CIRCULATION SPACE 6.27 In order that adequate acoustic separation may be achieved between the cellular breakout area and discussion area, it is recommended that the separating partition achieves a minimum sound insulation performance of 40dB D nt, w. In order that this performance may be achieved, it is recommended that the partition achieves a minimum sound insulation performance of 47dB R w. In order that this performance may be achieved, the following drywall construction is considered typically suitable: 48mm metal stud frame at 600mm centres 1x layer 12.5mm plasterboard each side 25mm mineral fibre insulation (20-30 kg/m3) in the cavity 6.28 The partition is to extend from the raised floor to the underside of the suspended ceiling system. As such, consideration will need to be given to sound transfer via the ceiling and floor voids. With regards to the floor voids, it is recommended that a floor void barrier is installed beneath this partition and also beneath the partition walls separating these spaces from the circulation area The ability of the in-situ installation to achieve the 38dB D nt, w performance is very much dependent upon the quality of workmanship of the void barrier installation. The void barrier material should achieve a minimum sound insulation performance of 30dB R w and 45dB D nc, w. A proprietary product with a lead core is recommended as it is easier to cut around building services systems than mineral fibre based barriers. Suitable proprietary products are; Soundstop CB10 Acoustic Curtain (Soundstop 10) Sound Reduction Systems Lamaphon CBX Flexible Acoustic Ceiling Void Barrier (CB10) Siderise 6.30 Detailed recommendations with regards to void barrier detailing are presented in Appendix F With regards to the ceiling void, however, it is understood that there is a high density of mechanical services systems passing over this space. As such, it is likely to be impracticable to install a ceiling void barrier above this partition. In light of this, it is recommended that the acoustic performance of the suspended ceiling is increased within these rooms in order to control noise transfer via the ceiling void. University of Westminster ADR1.1 17

22 6.32 Based on the manufacturer s literature for the Armstrong Oracle metal pan system, it is understood that a performance of 40dB D nc, w is achieved. This performance is unlikely to maintain the recommended 40dB D nt, w performance for this partition. As such, consideration should be given to introducing a metal backing to the ceiling tiles, above the absorbent layer in order that the airborne sound insulation performance of the ceiling system may be increased It is considered that introducing this metal backing to the ceiling tiles will enable a performance of around 45dB D nc, w to be achieved. It is considered that this performance will be suitable in maintaining the recommended 40dB D nt, w performance for this partition. PARTITIONS BETWEEN BREAKOUT/DISCUSSION AREAS AND CIRCULATION SPACE 6.34 In order that adequate acoustic separation may be achieved between the cellular breakout/discussion areas and the circulation space, it is recommended that the separating partition achieves a minimum sound insulation performance of 40dB R w. In order that this performance may be achieved, the following drywall construction is considered typically suitable: 48mm metal stud frame at 600mm centres 1x layer 12.5mm plasterboard each side 25mm mineral fibre insulation (20-30 kg/m 3 ) in the cavity 6.35 The partition should extend from the raised floor to the underside of the suspended ceiling system. It is understood that the suspended ceiling system within the circulation space is to be plasterboard while the suspended ceiling system in the breakout and discussion areas is to be plasterboard margins with perforated metal pan lay in grid system (with metal backing as recommended in Paragraph 6.32) It is recommended that the entrance doorsets to the breakout and discussion areas achieve a minimum sound insulation performance of 30dB R w This arrangement is considered adequate in maintaining adequate acoustic separation between the breakout/discussion areas and the circulation space. PARTITION BETWEEN SERVICES RISER AND DISCUSSION AREA 6.38 The separating wall between the services riser and the discussion area is to be of a drywall construction. It is recommended that this wall achieves a minimum sound insulation performance of 56dB R w. In order that this performance may be achieved, the following wall construction is considered typically suitable: 70mm metal stud frame at 600mm centres 2x layers 15mm Gyproc SoundBloc each side Cavity to be fitted with 50mm mineral fibre insulation University of Westminster ADR1.1 18

23 6.39 This construction is expected to provide a sound insulation performance of 56dB R w. This performance is considered suitable in controlling noise breakout from the risers to the adjacent spaces The partition should extend from the structural slab and continue uninterrupted through the raised floor and be adequately sealed to the underside of the structural roof. If the roof is to be of a profiled detail, adequate detailing should be employed in order to maintain acoustic integrity at this junction It is recommended that the doorset between this services riser and the circulation spaces achieves a minimum sound insulation performance of 35dB R w. EXTERNAL DOOR TO PLANT AREA 6.42 It is recommended that the door within the external façade between the circulation space and the 5 th floor external plant area achieves a minimum sound insulation performance of 40dB R w. This performance should be achieved by the doorset as a whole, including the framing, seals, etc. as opposed to the door panel alone. ACOUSTIC TREATMENT TO RWP S 6.43 Rain water pipes passing through the library spaces should be either cast iron on HDPE and should be lagged with 25mm unfaced mineral fibre insulation (30kg/m 3 min.). In addition, the pipes should be enclosed in a plasterboard enclosure formed of 2x layers 12.5mm plasterboard. The enclosure should extend from the structural slab and continue uninterrupted through the raised floor and suspended ceiling and be sealed to the underside of the structural roof. University of Westminster ADR1.1 19

24 7 Control of Reverberation REVERBERATION TIME CRITERIA 7.1 With regards to suitable criteria for the control of reverberation, there are no statutory requirements for this type of accommodation. Despite this, however, it is recommended that guidance is taken from the DfES document Building Bulletin 93 (BB93) Acoustic Design of Schools which forms Requirement E4 of Approved Document E of the Building Regulations It is considered that this standard is the most applicable for this further education establishment. 7.2 In light of the above, BB93 recommends the following standards in terms of mid-frequency reverberation times 2 (T mf ) for the relevant areas of the 5 th floor extension project. Table 9 Recommended Reverberation Time Criteria Internal Space Reverberation Time Criterion Library Areas T mf <1.0 seconds Breakout & Discussion Areas T mf <0.8 seconds Circulation Spaces (lobbies/stairwells, etc.) T mf <1.5 seconds Toilets T mf <1.5 seconds REVERBERATION WITHIN LIBRARY AREAS 7.3 From our conversations with Darnton EGS architects it is understood that Milliken Rush high performance loop pile modular carpet tiles are proposed for the floor finish within the min library areas, while the suspended ceiling system is proposed to be Armstrong Orcal perforated metal pan lay in grid tiles. The absorptive performance data for these products are presented in Table 10. Table 10 Absorptive Performance Criteria for Surface Finishes Absorptive Performance (ά) Surface Octave Band Centre Frequency (Hz) k 2k 4k Carpet Tiles Suspended Ceiling System Based on the above, we have undertaken an assessment to predict the mid frequency reverberation times in these open plan spaces. The results of our assessments suggest that the mid frequency reverberation time will be in the order of 0.5 seconds, which can be seen to be in accordance with the recommended criterion of <1.0 second for these spaces. REVERBERATION WITHIN DISCUSSION & BREAKOUT AREAS 7.5 From our conversations with Darnton EGS architects it is understood that Milliken Rush high performance loop pile modular carpet tiles are proposed for the floor finish within the min library areas, while the suspended ceiling system is proposed to be 2 arithmetic average of reverberation times in 250, 500 and 1kHz octave bands University of Westminster ADR1.1 20

25 Armstrong perforated MDF wood veneer ceiling panels from the Madera range. The absorptive performance data for this ceiling system is presented in Table 11. Table 11 Absorptive Performance Criteria for Surface Finishes Absorptive Performance (ά) Surface Octave Band Centre Frequency (Hz) k 2k 4k Madera Ceiling Tiles Based on the above, we have undertaken an assessment to predict the mid frequency reverberation times in these cellular spaces. The results of our assessments suggest that the mid frequency reverberation time will again be in the order of 0.5 seconds, which can be seen to be in accordance with the recommended criterion of <0.8 second for these spaces. REVERBERATION WITHIN STAIR CORES & CIRCULATION AREAS 7.7 Within the stair cores it is proposed to install a suspended perforated metal pan ceiling system to the top landing areas with the Milliken Rush carpet tiles to the floors and stairs. Our calculations indicate that these surface finishes will result in reverberation times in accordance with the recommended <1.5 second criterion. 7.8 Within the circulation area at the eastern end of the building it is proposed to install a plasterboard ceiling. The floor finish is proposed to be the Milliken Rush carpet tiles. Our calculations indicate that these surface finishes will result in reverberation times in accordance with the recommended <1.5 second criterion. WSP Acoustics University of Westminster ADR1.1 21

26 Appendix A Terminology Glossary of Acoustic Noise Noise is defined as unwanted sound. Human ears are able to respond to sound in the frequency range 20 Hz (deep bass) to 20,000 Hz (high treble) and over the audible range of 0 db (the threshold of perception) to 140 db (the threshold of pain). The ear does not respond equally to different frequencies of the same magnitude, but is more responsive to mid-frequencies than to lower or higher frequencies. To quantify noise in a manner that approximates the response of the human ear, a weighting mechanism is used. This reduces the importance of lower and higher frequencies, in a similar manner to the human ear. Furthermore, the perception of noise may be determined by a number of other factors, which may not necessarily be acoustic. In general, the impact of noise depends upon its level, the margin by which it exceeds the background level, its character and its variation over a given period of time. In some cases, the time of day and other acoustic features such as tonality or impulsiveness may be important, as may the disposition of the affected individual. Any assessment of noise should give due consideration to all of these factors when assessing the significance of a noise source. The most widely used weighting mechanism that best corresponds to the response of the human ear is the A -weighting scale. This is widely used for environmental noise measurement, and the levels are denoted as db(a) or L Aeq, L A90 etc, according to the parameter being measured. The decibel scale is logarithmic rather than linear, and hence a 3 db increase in sound level represents a doubling of the sound energy present. Judgement of sound is subjective, but as a general guide a 10 db(a) increase can be taken to represent a doubling of loudness, whilst an increase in the order of 3 db(a) is generally regarded as the minimum difference needed to perceive a change under normal listening conditions. An indication of the range of sound levels commonly found in the environment is given in the following table. Typical sound levels found in the environment Sound Level 0 db(a) Threshold of hearing 20 to 30 db(a) Quiet bedroom at night Location 30 to 40 db(a) Living room during the day 40 to 50 db(a) Typical office 50 to 60 db(a) Inside a car 60 to 70 db(a) Typical high street 70 to 90 db(a) Inside factory 100 to 110 db(a) Burglar alarm at 1m away 110 to 130 db(a) Jet aircraft on take off 140 db(a) Threshold of Pain University of Westminster ADR1.1 22

27 Sound Pressure Sound Pressure Level (Sound Level) Decibel (db) Terminology Relating to Noise Sound, or sound pressure, is a fluctuation in air pressure over the static ambient pressure. The sound level is the sound pressure relative to a standard reference pressure of 20µPa (20x10-6 Pascals) on a decibel scale. A scale for comparing the ratios of two quantities, including sound pressure and sound power. The difference in level between two sounds s 1 and s 2 is given by 20 log 10 ( s 1 / s 2 ). The decibel can also be used to measure absolute quantities by specifying a reference value that fixes one point on the scale. For sound pressure, the reference value is 20µPa. A-weighting, db(a) The unit of sound level, weighted according to the A- scale, which takes into account the increased sensitivity of the human ear at some frequencies. Noise Level Indices L eq,t L max,t L 90,T L 10,T Free-Field Façade Fast/Slow Time Weighting Octave Band D nt,w R w Reverberation Noise levels usually fluctuate over time, so it is often necessary to consider an average or statistical noise level. This can be done in several ways, so a number of different noise indices have been defined, according to how the averaging or statistics are carried out. A noise level index called the equivalent continuous noise level over the time period T. This is the level of a notional steady sound that would contain the same amount of sound energy as the actual, possibly fluctuating, sound that was recorded. A noise level index defined as the maximum noise level during the period T. L max is sometimes used for the assessment of occasional loud noises, which may have little effect on the overall L eq noise level but will still affect the noise environment. Unless described otherwise, it is measured using the 'fast' sound level meter response. A noise level index. The noise level exceeded for 90% of the time over the period T. L 90 can be considered to be the "average minimum" noise level and is often used to describe the background noise. A noise level index. The noise level exceeded for 10% of the time over the period T. L 10 can be considered to be the "average maximum" noise level. Generally used to describe road traffic noise. Far from the presence of sound reflecting objects (except the ground), usually taken to mean at least 3.5m At a distance of 1m in front of a large sound reflecting object such as a building façade. Averaging times used in sound level meters. A range of frequencies whose upper limit is twice the frequency of the lower limit. The single number quantity that characterises airborne sound insulation between rooms over a range of frequencies. Single number quantity that characterises the airborne sound insulating properties of a material or building element over a range of frequencies. The persistence of sound in a space after a sound source has been stopped. University of Westminster ADR1.1 23

28 Appendix B Site Plan Proposed plant area Proposed 5 th floor extension area Measurement Position (5 th Floor Level) N University of Westminster ADR1.1 24

29 Appendix C Noise Measurement Results 14:30 13:30 12:30 11: University of Westminster, New Cavendish Street Environmental Noise Monitoring - L Aeq, L Amax, fast Noise Data 20:30 21:30 22:30 23:30 00:30 01:30 02:30 03:30 04:30 05:30 06:30 07:30 08:30 09:30 10:30 Time (hh:mm) LAmax LAeq 19:30 18:30 17:30 16:30 15:30 Measured Sound Pressure Level (db re 20x10-6 Pa.) University of Westminster ADR1.1 25

30 14:30 13:30 12:30 11: University of Westminster, New Cavendish Street Environmental Noise Monitoring - L A10, L A90 Noise Data 20:30 21:30 22:30 23:30 00:30 01:30 02:30 03:30 04:30 05:30 06:30 07:30 08:30 09:30 10:30 Time (hh:mm) LA10 LA90 19:30 18:30 17:30 16:30 15:30 Measured Sound Pressure Level (db re 20x10-6 Pa.) University of Westminster ADR1.1 26

31 University of Westminster, New Cavendish Street Environmental Noise Monitoring - 16 hour Daytime Noise Spectra Hz 125Hz 250Hz 500Hz 1kHz 2kHz 4kHz 8kHz Octave Band Centre Frequency (Hz) LA10 LAeq LA90 Measured Sound Pressure Level (db re 20x10-6 Pa.) University of Westminster ADR1.1 27

32 University of Westminster, New Cavendish Street Environmental Noise Monitoring - 8 hour Night Time Noise Spectra Hz 125Hz 250Hz 500Hz 1kHz 2kHz 4kHz 8kHz Octave Band Centre Frequency (Hz) LA10 LAeq LA90 Measured Sound Pressure Level (db re 20x10-6 Pa.) University of Westminster ADR1.1 28

33 Appendix D External Building Fabric Performance Specifications Acoustic Performance Specification for External Building Fabric System SOUND INSULATION: Each complete external façade system, including frames, glass, seals (opening or otherwise), spandrel panels etc. shall be tested in full accordance with BS EN ISO 140-3:1995 Acoustics. Measurement of sound insulation in buildings and of building elements - Laboratory measurement of airborne sound insulation of building elements. The tests shall be conducted in an approved, independent, specialist acoustic test laboratory. The size of test specimen should be at least the complete area of façade in one cellular office (and inclusive of all elements), and up to the limit of the test centre maximum size (in accordance with BS EN ISO 140-3). It is thought that the façade area of one cellular office will be sufficient. The sound insulation testing shall be for 1/3 octave frequency bands from 50Hz to 10000Hz inclusive. These results, together with calculated octave band values from 125Hz to 4000Hz, shall be provided for each glazing unit. The 63Hz octave band test result should also be reported for information, although it is accepted that its accuracy may be limited due to test chamber dimensions. The following minimum Sound Reduction Indices shall be achieved by the composite façade system: Required Minimum Glazing SRI's for Composite Façade Octave Band Centre Frequency (Hz) k 2k 4k 8k University of Westminster ADR1.1 29

34 Appendix E Attenuator Schedule University of Westminster ADR1.1 30

35 Appendix F Ceiling & Floor Void Barrier General Detailing Junctions with the soffit If a trapezoidal profiled metal deck is present forming the structural soffit. This will introduce issues with achieving a good acoustic seal between the void barrier material and the soffit. In order that a good acoustic seal may be achieved at the junction between the void barrier and the profiled soffit the following treatment is recommended. The trapezoidal profiles should firstly be packed with mineral fibre insulation (min. 40 kg/m 3 ) to a length of 200mm past the location of the void barrier junction with the soffit, each side of the barrier junction (i.e. 400mm length in total). A sheet of ply board should then be fixed to the underside of the soffit, holding the mineral fibre packing within the trapezoidal profiles. This treatment should extend along the line of the junction between the void barriers and profiled soffit, where the profiles run perpendicular to the partition line. The void barrier should then be fixed to the underside of the ply board and to the external walls by means of continuous and interrupted steel angles. The angles should clamp the barrier to the soffit/external wall trapping and compressing it across the whole length. The barrier material should extend a minimum 50mm beyond the face of the angles. This treatment is sketched diagrammatically below: University of Westminster ADR1.1 31

36 Where steel beams are located above partition lines, the void barrier should be installed such that it wraps to one side of the beam. Junctions with the suspended ceiling The void barrier should be secured to the head of the partition, through the suspended ceiling. The void barrier material should be secured by a steel angle which runs between the T s between adjacent suspended ceiling panels. The angles should be screwed to clamp the barrier to the head of the partition, trapping and compressing it across the whole length. The barrier material should extend a minimum 50mm beyond the face of the angles. It is imperative to the acoustic integrity of the partitions that the barrier material is cut as tightly as possible round the profiles of the suspended ceiling. It is recommended that any gaps are no greater than 3mm and are sealed both sides with a liberal application of non hardening mastic. Junctions between void barriers Where junctions between void barriers occur, there should be an overlap of a minimum of 100mm (i.e. the void barrier should abut the other, and be folded one way to return along the office front barrier by a minimum of 100mm). A flat metal strip should then be fixed vertically about the junction, from the soffit steel angle to the steel angle at the partition head. A second strip should then be positioned on the opposite face of the barrier and the two plates screwed together clamping and compressing the two barrier layers together along the entire height of the junction. University of Westminster ADR1.1 32

37 Services Penetrations through the barrier Where services penetrate the barrier, it is essential that holes are cut such that there is as tight a fit as is possible. Large gaps around the edges of services penetrations will result in significant compromises in acoustic performance between rooms. Holes for services penetrations should be cut using a trimming knife smaller in dimension than the penetration itself such that a tight seal is achieved once the service pipe/duct is passed through. Holes should be made by means of a star cut. The star profiles should then be wrapped with cut strips of void barrier material well sealed onto the services duct/pipe itself by continuous duct tape to the full length of the profiles and slightly beyond. Where existing services cannot be removed and refitted through the cut hole in the void barrier, a cut should be made from the bottom edge of the barrier so that the barrier can be formed around the penetration and the duct/pipe fitted into the star cut hole. The cut in the barrier should then be covered by a 50mm strip of additional void barrier material to both sides of the main curtain and glued/screwed to hold be held in position. University of Westminster ADR1.1 33

38 Appendix G Report Limitations This report has been prepared for the titled project or named part thereof and should not be used in whole or part and relied upon for any other project without the written authorisation of WSP Environmental Limited. WSP Environmental Limited accepts no responsibility or liability for the consequences of this document if it is used for a purpose other than that for which it was commissioned. Persons wishing to use or rely upon this report for other purposes must seek written authority to do so from the owner of this report and/ or WSP Environmental Limited and agree to indemnify WSP Environmental Limited for any and all loss or damage resulting therefrom. WSP Environmental Limited accepts no responsibility or liability for this document to any other party other than the person by whom it was commissioned. The findings and opinions expressed are relevant to the dates of the site works and should not be relied upon to represent conditions at substantially later dates. Opinions included therein are based on information gathered during the study and from our experience. If additional information becomes available which may affect our comments, conclusions or recommendations WSP Environmental Limited reserve the right to review the information, reassess any new potential concerns and modify our opinions accordingly. University of Westminster ADR1.1 34