Environmental Noise Study of. Findlay Creek Public School Findlay Creek Drive, Ottawa, Ontario. R1. Prepared for: N45 Architecture Inc.

Transcription

1 Environmental Noise Study of Findlay Creek Public School 3010 Findlay Creek Drive, Ottawa, Ontario. R1 Prepared for: N45 Architecture Inc. Prepared by: Eric Sladic February 5 th, 2015

2 Contents 1.0 Introduction Facility Description Noise Sources Points of Reception Methodology Used in Noise Impact Calculation Acoustic Assessment Summary Conclusion... 13

3 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 1 of Introduction State of the Art Acoustik Inc. has been commissioned by N45 Architecture to complete an environmental noise study for the Findlay Creek Public School development to be located at 3010 Findlay Creek Drive, Ottawa, Ontario. Due to the school s proximity to local residences, this report s environmental noise assessment and design recommendations will ensure adherence to the City of Ottawa s noise by-law and the Environmental Noise Control Guidelines. This requires that the noise pressure level from all mechanical equipment must be below 50 dba SPL during the day and below 45dBA SPL during the night (or the existing background noise level, whichever is higher) at noise sensitive points of reception. This assessment assumes the mechanical equipment operates at all times. The significant noise sources which are being considered for this assessment are: o Twelve Roof Top Air Handling Units (RTUs): The acoustical data for the Aaon RTUs have been provided by McKee Engineering and have been confirmed to represent the full radiated noise power levels from the casing of the RTUs to the environment. This data has been summarized in Tables and o Two Washroom Exhaust Fans: As provided by McKee Engineering, these fans are 1300 c.f.m. and of the rooftop mounted domex style. The exact model is yet unknown. This report will use representative data from a similar 1300 c.f.m. Carnes Fan VEBK10P1 rooftop fan that is of the domex style. This data has been summarized in Tables and Facility Description The school building being reviewed will be located at 3010 Findlay Creek Drive at the intersection of Kelly Farm Drive in Ottawa, Ontario. It will be a 2 storey building which is approximately 8 meters tall and be located in a neighbourhood which contains residential buildings. 2.1 Operation hours for the Facility The twelve roof top air handling units (RTUs) and two exhaust fans are all assumed to run 24 hours a day, seven days a week. 2.2 Site Plan and Scaled Area Location Plan On the following page is a copy of the site plan (Figure 2.2.1) for the Findlay Creek School from N45 Architects and on the following page is a zoning plan (Figure 2.2.2) from the City of Ottawa GeoOttawa map service:

4 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 2 of 13 NORTH Figure Findlay Creek South Public School, Orleans, Ontario Site Plan

5 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 3 of 13 Kelly Farm Drive Zoning Info: I1E - Minor Institutional Zone (Sec ) NORTH Location of Findlay Creek School 100m 500ft Findlay Creek Drive Figure Location of Findlay Creek School Source City of Ottawa emaps 2.3 Noise By-Law and Noise Control Guidelines The City of Ottawa noise by-law no states: No person shall use or operate or cause to be used or operated any exhaust fan, exhaust system, intake fan, generators, dryer in a commercial car wash or similar device which includes combustion exhaust of a high efficiency furnace, the noise from which has a level greater than 50 dba when measured at the point of reception. The City of Ottawa Environmental Noise Control Guidelines (May 10, 2006) states that the highest permissible Noise Sound Pressure Level at the plane of window at a noise sensitive location in a Class 1 area at night is 45 dba SPL. Where the: "point of reception" means any point on the premises of a person where sound or vibration originating from other than those premises is received; For our analysis, the points of reception are chosen based on the principle of "predictable worst case scenario" for noise impact. This will allow us to calculate the largest noise impact and mitigate it accordingly.

6 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 4 of Noise Sources The following sections describe the characteristics of the noise source(s). 3.1 Significant Noise Sources Tables and summarize the sound power levels for the twelve Roof Top Air Handling Units (RTUs) and two exhaust fans. These RTU noise sources are located on the roof of the school and have been placed in the model based on information received from McKee Engineering. The locations of the RTUs can be found in Figures and on the next page. The RTU noise level data in the tables below (from Aaon data sheet in Appendix) are the total radiated sound power levels as provided by the equipment manufacturer, Aaon. Noise SWL Level Used in Manufacturer Model Quantity Sources Report (dba) RTUs Aaon RQ 2-3 Ton 1 78 RTUs Aaon RN 6-11 Ton 8 88 RTUs Aaon RN Ton 2 91 RTUs Aaon RN Ton 1 91 *Washroom Exhaust Fans Carnes VEBK10P1 2 72* Table Summary of Noise Power Levels Used in this Analysis (*see paragraph below) Noise Source 63Hz 125Hz 250Hz 500Hz 1KHz 2KHz 4KHz 8KHz Total dba RTU Aaon RQ 2-3 ton RTU Aaon RN 6-11Ton RTU Aaon RN Ton RTU Aaon RN Ton *Exhaust Fan, Carnes VEBK10P * Table Total Radiated Octave Band Sound Power Levels of Noise Sources in db as Provided by Aaon *Since the washroom exhaust fans have not been selected yet. This is representative data from known 1300 c.f.m. Carnes domex type washroom exhaust fans. However, since the total noise from both these fans combined (75dBA) is more than 10dBA lower the total noise from the other 12 RTUs, the noise from these fan can safely be omitted from this study. From this point on, we will not include the fans in this report.

7 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 5 of 13 Figure Location of 12 x RTUs on the Roof of the School as provide by McKee Eng. Locations of 12 RTUs as seen, looking to the N-E towards the intersection of Findlay Creek Dr. and Kelly Farm Dr. Figure D Illustration of RTU locations as seen in Acoustic Model NORTH

8 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 6 of Noise Source Summary Table Source ID Source Description 1 x RTU: Aaon RQ 2-3 ton 8 x RTU: Aaon RN 6-11 ton 2 x RTU: Aaon RN ton Source Location 1 Sound Characteristics 2 Noise Control Measures 3 Sound Power Level (dba) O S U 78* O S U 88* O S U 91* 1 x RTU: 4 O S U 91* Aaon RN ton Table 3.2 Acoustical Information for each significant source included in this study. 1. Source Location: O - located/installed outside the building, including on the roof I - located/installed inside the building 2. Sound Characteristics: S: Steady Q: Quasi Steady Impulsive I: Impulsive B: Buzzing T: Tonal C: Cyclic 3. Noise Control Measures S: silencer, acoustic louver, muffler A: acoustic lining, plenum B: barrier, berm, screening L: lagging E: acoustic enclosure O: other U: uncontrolled * This data may be found in the Appendix.

9 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 7 of Points of Reception Points of reception have been selected by using worst case situations for the following types of development: permanent or seasonal residences, hotels/motels, nursing/retirement homes, rental residences, hospitals, camp grounds, and noise sensitive buildings such as schools and places of worship. We have chosen three Points of Reception (POR) for the noise level analysis. POR1 is at ground level (1.5 meters high) at a residence located across the street on Kelly Farm Drive (approximately 65 meters to the North). POR2 is also at ground level (1.5 meters high) at a residence at the intersection of Kelly Farm Drive and Findlay Creek Drive which is approximately 70 meters to the North-East. POR3 is located at ground level (1.5 meters) at a residence which is located across the street on Findlay Creek Drive which is approximately 85 meters to the East. All the distances are measured from the closest wall of the school to the point of reception. These points are illustrated below. POR2 1.5m above 70 m POR1 1.5m above 65 m 85 m POR3 1.5m above NORTH Figure 3.3 Illustration of Points of Receptions and Significant Noise Sources (colours will display properly when this document is printed in colour or viewed on a computer) The minimum distances from the source building to the points of reception are stated below: POR1 Residence, 65 meters to the North (1.5 meters above ground) POR2 Residence, 70 meters to the North-East (1.5 meters above ground) POR3 Residence, 85 meters to the South-East (1.5 meters above ground)

10 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 8 of Methodology Used in Noise Impact Calculation The following sections describe the methodology and software used to model the sound pressure levels at the points of reception due to the noise sources while taking into account parameters such as source levels, distance, topography, barriers and building geometry. 5.1 Procedure Used to Assess Noise Impact at Each Point of Reception This environmental noise analysis was done using an environmental noise modeling software called Cadna/A which references ISO Cadna/A predicts environmental noise through calculations based on a 3D model which uses geometrical, landscape and topography data, combined with details of the proposed construction and the noise source power levels. We created a 3D rendering of the neighbourhood around the school and placed the noise sources in the model (represented by the blue 1 crosses) with the sound power levels described in this report. The colours 1 on the ground and building represent the sound pressure level in that area. Sound power levels per octave band were entered into the Cadna/A at the source s location and the resulting sound pressure levels were calculated at the points of reception. Other Parameters/Assumptions Used in Calculations The following chart describes the parameters used in the Cadna/A model: Parameter Value/Condition Temperature ( C) 10 Relative Humidity (%) 70 *All Buildings, Roads and Land Fully Reflective Absorption Coefficient Alpha = 0 Maximum Order of Reflection 2 *No sub. Of neg. Ground Att. ON *No neg. path difference ON Table 5.1 Parameters used in Cadna/A modeling. *These parameters set to simulate the worst case scenario for sound reflection

11 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 9 of Acoustic Assessment Summary This section summarizes the Cadna/A noise pressure mapping results. Section 6.1 below illustrates the steady state sound pressure levels generated by all the RTUs. Section 6.2 assesses the noise impact of quieter RTUs. 6.1 Acoustic Assessment Summary for All Equipment with Current RTUs The next two figures illustrate the predicted sound pressures due to the noise sources at the PORs. The first figure is in 2D with the colour map at a height of 1.5m (6.1.1) and the second is in 3D with the colour height of 1.5m (6.1.2). The figures are similar to a temperature map showing hot zones and cool zones. The red coloured zones are areas with levels at or above 50 dba (which is above the City of Ottawa noise by-law limit of 50dBA); green coloured zones are levels less than 50 dba. The legend attached to the image explains the different colour levels. POR1 52 dba SPL at 1.5m height POR2 48 dba SPL at 1.5m height POR3 51 dba SPL at 1.5m height Figure Model Results 1 : Sound Pressure Levels (SPL) due to Noise Sources 1 colours will display properly when this document is printed in colour or viewed on a computer

12 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 10 of 13 POR2 48 dba SPL at 1.5m height POR1 52 dba SPL at 1.5m height POR3 51 dba SPL at 1.5m height Figure Model Results 1 : Sound Pressure Levels (SPL) due to Noise Sources 1 colours will display properly when this document is printed in colour or viewed on a computer It can be seen in the figures above that the noise exceed 50dBA during the day and exceed 45dBA during the night. The Sound Pressure Levels are summarized below in Table Equipment POR1 (dba) POR2 (dba) POR3 (dba) 12 RTUs Table Sound Pressure Levels (dba) at PORs Under the worst case scenario (all 12 RTUs running), we predict that the RTUs produce sound pressure levels that are above the City of Ottawa noise by-law and guidelines during both the day and the night. Ideally, it would be recommended to have the noise levels at the most noise sensitive points of reception to be 3dBA below 45dBA (42 dba). This extra 3dBA safety margin would ensure compliance to the City of Ottawa noise by-law and guidelines. To reduce the noise the points of reception we propose that quieter RTUs be used. The next section investigates this.

13 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 11 of Acoustic Assessment Summary with Recommended Quieter RTUs In order to bring down the noise at the most sensitive points of reception (PORs) we recommend quieter RTUs. If quieter units cannot be found, other noise mitigation measures may have to be investigated such as a concrete barrier around all the units on the roof or relocation of the RTUs. Currently, the noise levels as seen in Table show that noise levels are as much as 7dBA above 45dBA SPL and 10dBA above our desired target of 42dBA SPL. In order to reduce the predicted noise levels we have reduced the overall sound powers of the RTUs in Table as show below in Table Noise Source 63Hz 125Hz 250Hz 500Hz 1KHz 2KHz 4KHz 8KHz Recommended Total SWL (dba) Current SWL RTU Aaon RQ 2-3 ton (unchanged) RTU Aaon RN 6-11Ton (reduced 7 dba total) RTU Aaon RN Ton (reduced 8 dba total) RTU Aaon RN Ton (reduced 8 dba total) Table Octave Band Sound Power Levels of RTUs with reduced Noise Levels Based on the above recommended quieter RTUs (11units reduced by 8dBA SWL and the smallest unit unchanged) the acoustic model predicts the following noise pattern and levels (Table below). These levels are below or very close to the target of 42dBA SPL. (dba)

14 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 12 of 13 POR2 41 dba SPL at 1.5m height POR1 43 dba SPL at 1.5m height POR3 41 dba SPL at 1.5m height Figure Model Results 1 : Sound Pressure Levels (SPL) due to Quieter RTUs 1 colours will display properly when this document is printed in colour or viewed on a computer

15 REP N45 FINDLAY CREEK PUBLIC SCHOOL - ENVIRONMENTAL NOISE ANALYSIS - R1 Page 13 of Conclusion We have found that the currently selected roof top units (with radiated sound power levels as provided by the manufacturer) will create noise levels at the most noise sensitive points of reception near the school which are up to 7dBA higher than is acceptable by the City of Ottawa. We recommend that the RTUs selected for this school to have radiated sound power levels at the casing which are not louder than as shown in Table This amounts to a 8dBA reduction in noise power levels for the 11 loudest RTUs which were presented to us. If RTUs with this reduction in radiated sound power levels can be selected, the worst case noise level at a sensitive point of reception will be 43dBA SPL (POR1 in Figure 6.2.1). This will be well below the City of Ottawa Noise by-law and Environmental Noise Control Guidelines for both the day and night with a 2dBA safety factor. Should you have any questions regarding this report, please do not hesitate to contact us. Prepared by: Reviewed by: Eric Sladic B.Sc., B.Eng. Acoustical Consultant Claude Fortier, Ph.D. Principal

16 APPENDIX

17 AAON Condenser Radiated Sound Levels Sound Power Level Fans Dia RPM LwA Inlet HB 2-3 Ton Outlet Total Inlet HB 4-5 Ton Outlet Total Inlet RQ 2-3 Ton Outlet Total Inlet RQ 4-5 Ton Outlet Total Inlet RN 6-11 Ton Outlet RN Ton RN Ton Total Inlet Outlet Total Inlet Outlet Total Inlet RN Ton Outlet Total Inlet RN Ton Outlet Total Inlet RN Ton Outlet Total Inlet RN Ton Outlet Total Inlet RN 90 Ton Outlet Total Inlet RN Ton Outlet Total Inlet RN Ton MC Outlet Total Inlet RN Ton MC Outlet Total This is the total radiated sound data for the rooftop units. The only models used will be the RN and RQ units. The sizes for the rooftop units are as follows: RTU-1 = 16 tons RTU-2 = 10 tons RTU-3 = 8 tons RTU-4 = 8 tons RTU-5 = 9 tons RTU-6 = 8 tons RTU-7 = 7 tons RTU-8 = 2 tons RTU-9 = 14 tons RTU-10 = 12 tons RTU-11 = 9 tons RTU-12 = 7 tons

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