SITE AND BUILDING INFORMATION

Transcription

1 Page 1 Mr. Maneesh Poddar YORK Developments 303 Richmond St, Suite 201 London, ON N6B 2H8 Re: Preliminary Pedestrian Wind Assessment London, Ontario RWDI Reference Number: maneesh.poddar@yorkdev.ca Dear Maneesh, Rowan Williams Davies & Irwin Inc. (RWDI) has prepared this letter to present our opinion on the potential pedestrian wind conditions on and around the proposed in London, Ontario. Our findings are based on a qualitative assessment of the wind conditions in the context of the local wind climate and our expert understanding of wind flow around buildings. This letter is required by the City of London in support of the Zoning By-law Amendment submission for this project. SITE AND BUILDING INFORMATION The proposed development will be located south of Southdale Rd. W. and east of Bostwick Rd. in London, Ontario (see Image 1). The site is currently empty lands. The site is immediately surrounded by low-rise residential buildings to the north, industrial/commercial buildings to the east, and empty lands to the south and west (see Image 1). Surrounding buildings farther away from the site are generally low-rise and farmlands in all directions. Downtown London is approximant 7 km to the northeast. SITE 1 SITE 3 SITE 5 SITE 2 SITE 6 Image 1 Aerial View of Existing Site and Surroundings (Image Courtesy of Google Earth ) Image 2 Proposed Development

2 Page 2 Based on the drawings received by RWDI on February 7, 2017, the proposed development consists of Sites 1, 2, 3, 5 and 6 (see Images 2 and 3). This report focused on wind conditions on and around Sites 1, 3 and 5, as summarized below: Site 1 - located at the northwest corner of the project site and consists of two residential towers of 18 and 21-storeys on a 3-storey podium. Site 3 - located to the east of Site 1, and consists of two residential towers of 6 and 9-storeys and a row of 1-storey townhouses. Site 5 - located at the northeast corner of the project site, and consists of 13-storey and 17-storey residential towers and a 3-storey commercial building (see Image 3). The pedestrian areas of concern are shown in Image 3 and include the following: The main entrances to the buildings at each site as marked by red triangle in Image 3. Public sidewalks along Southdale Rd. W and Bostwick Rd. Outdoor courtyards at grade level on Sites 1, 3 and 5 (areas marked by light green in Image 3). Rooftop terraces on top of the 3-storey podium of Site 1, the roof of the 6-storey tower of Site 3, and Level 13 of residential tower of Site 5 (areas marked by dark green in Image 3). Image 3 Site Plan Showing Entnraces, Outdoor Courtyards and Roof Terraces and the Predicted Wind Flow Patterns around the Proposed Developement WIND DATA Long-term wind statistics at the London International Airport were analyzed for the summer (May through October) and winter (November through April) seasons (see Image 4). When all winds are considered (regardless of speed), winds from south, south-southwest, west through northwest and east directions are predominant during the summer. During the winter, winds from the southwest through northwest and east directions are predominant. Strong winds of a mean speed greater than 30 km/h (yellow and red bands) occur more often in the winter than in the summer.

3 Page 3 Wind Speed (km/h) Calm > Probability ( Summer W Summer (May through October) Winter (November through April) Image 4 Directional Distribution of Winds, London International Airport ( ) PEDESTRIAN WIND ASSESSMENT To provide an opinion on the overall wind conditions expected around the proposed development, RWDI reviewed the following: long-term meteorological data for the area (as described above); drawings and renderings of the proposed development; and information regarding the surroundings. These data, in conjunction with our engineering judgement, allow us to summarize the expected wind conditions as outlined below. Public Sidewalks around the Development The sidewalks along Southdale Rd. W. and Bostwick Rd. are separate from the buildings of Sites 1, 3 and 5 through setbacks of 10 m or more. This is a positive feature that keeps any local wind accelerations around the buildings away from the sidewalks. Local accelerations might occur around the southwest corner of the south tower of Site 1; however, the predicted wind speeds along the sidewalks are expected to be comfortable for the intended active pedestrian use of these areas throughout the year. Site 1 Main Entrances Prevailing winds are expected to be intercepted by the tall towers of Site 1 and be redirected to the ground and approach the locations of the entrances along the perimeter of the towers (see Image 3). The building setback at the ground level is a positive design feature that will provide shelter at the location of the entrances around the perimeter of the buildings. Also, the chamfered northwest corner of the 3-storey podium is a positive feature that will reduce wind accelerations at this location where a retail entrance is located. Wind speeds might be higher-than-desired at the entrances around the base of the two towers during the winter. We recommend extending the entrance canopies and installing wind screens on both sides of the

4 Page 4 entrances. Alternatively, increasing the recess of these two entrances from the building façade would provide further protection. Prevailing westerly and easterly winds are expected to accelerate through the pedestrian walkway at the ground level opening running east-west. As a result, accelerated wind speeds are expected along this walkway and at the location of the entrance at its west end. We recommend recessing any entrances along this walkway or installing wind screens on both sides of it. Wind speeds along the walkway running northsouth are expected to be calmer as the walkway is perpendicular to the prevailing wind directions. Ground-Level Courtyards The outdoor courtyard at the northwest corner of Site 1 is exposed to the prevailing winds from the southwest through northwest during the summer. The courtyard at the northeast corner of the 18-storey tower may be affected by the wind accelerations around the tower. The courtyard to the west of the 21- storey residential tower is also exposed to winds both directly, and after they are redirected down by the tall building facade. Wind speeds at these courtyards might be higher-than-desired for passive activities during the summer. The proposed landscaping around these areas is a positive design feature; however, we recommend ensuring under-planting is also included. We also recommend extending the canopies along the west façade of the 21-storey residential tower to keep winds away from the ground. Above-Ground Terraces The outdoor terrace at the roof of the 3-storey podium of Site 1 is exposed to the prevailing winds during the summer. Winds are expected to accelerated between the two towers on two sides of this terrace. Higher-than-desired wind speeds are expected on this terrace during the summer. If this area is meant for prolonged passive use, we recommend installing tall parapets (2 to 2.5m tall with 20 to 30% porosity) around its perimeter. Landscaping elements installed throughout this terrace is expected to further protect this area from prevailing winds. Site 3 Main Entrances The main entrance on the west side of the 9-storey building is protected from the prevailing easterly winds. The ground floor at the location of this entrance is significantly recessed, which is a positive design feature for reducing the effects of westerly winds. Also, the entrance is protected from winds by the building projection on its north side. As a result, comfortable wind conditions are expected at this entrance. Winds are expected to accelerate through the opening between the 6-storey and the 9-storey buildings of Site 3. As a result, wind conditions at the entrance along this opening at the southwest corner of the 9- storey building might be higher-than-desired during the winter. We recommend recessing this entrance or installing wind screens on both sides of it. Appropriate wind conditions are expected at the two back entrances/exits to parking spaces due to their recessed nature and at the townhouse entrances as a result of the limited height of the townhouses. Ground-Level Courtyards The park on the south portion of Site 3 will be sheltered by future buildings and dense trees in all directions. As a result, suitable wind conditions are expected in the summer when this area will be used the most. Additional local wind protection is needed for any seating areas in the park and can take the form of wind screens and landscaping around the seating areas.

5 Page 5 Above-Ground Terraces The tall tower of Site 1 provides some protection from the prevailing southwesterly and northwesterly winds at the roof terrace at Level 6. However, this area is still exposed to the easterly winds and winds accelerating between the two towers on Site 1, which could result in higher-than-desired wind speeds. We recommend installing tall parapets (2 to 2.5m tall with 20 to 30% porosity) along the east and west sides of this terrace. Additionally, landscaping elements as suggested above can provide further protection. Site 5 Main Entrances Comfortable wind conditions are expected at the entrances to the commercial building of Site 5 as a result of its limited height and the recessed west façade at this entrance location. The canopy above the main entrance to the residential building is a positive feature that keeps wind accelerating down the tower away from the ground. However, this entrance can still be exposed to the winds accelerating around the corners of the 13-storey tower. We recommend installing wind screens or tall planters on both sides of this entrance. Ground-Level Courtyards The courtyard at the northwest corner of the 3-storey building is fully exposed to prevailing winds. The two courtyards north of the 17-storey building are partially sheltered from the south and southwest winds, but may be affected by winds from the east, and west through north directions. As a result, wind speeds are predicted to be slightly higher-than-desired for passive pedestrian activities in the summer. We recommend installing wind screens or trees with under-plantings around the perimeter of these courtyards. We also recommend installing a trellis or canopy along the north façade of the 17-storey residential tower to keep winds away from the ground and the courtyards on its north side. Above-Ground Terraces The roof terrace of 13-storey tower is exposed to the prevailing winds during the summer, which could result in higher-than-desired winds for passive activities. Wind control measures suggested for other terrace above (tall parapets, landscaping and trellis) can be used to reduce the wind activities. CONCLUSION The proposed development has a number of positive design features such as the setback from the sidewalks, recessed ground level of Site 1 and recessed entrances for several buildings on Sites 3 and 5. As a result, wind conditions along the sidewalks are not expected to be negatively affected by the addition of the proposed development to the site, and acceptable wind conditions are expected along sidewalks. Also, appropriate wind conditions are expected at the entrances around the podium at Site 1, west entrance and back entrances/exits at Site 3 and entrances to the commercial building at Site 5. Higher-than-desired wind speeds are expected at the entrances around the perimeter of the towers at Site 1, along the walkway running east-west under the building at Site 1, at the south entrance within the eastwest passageway of Site 3 and at the main entrance to the residential tower at Site 5 during the winter, and most courtyards and elevated terraces during the summer. Mitigation measures have been provided herein to ensure comfortable wind conditions are achieved at these areas. If desired, wind tunnel tests can be conducted to quantify these wind conditions and evaluate the effectiveness of these control measures.

6 Page 6 CLOSING We trust this meets your current requirements for this project. Should you have any questions or require additional information, please do not hesitate to contact us. Yours very truly, ROWAN WILLIAMS DAVIES & IRWIN Inc. Saba Saneinejad, Ph.D. Technical Coordinator