revera retirement residence - barrie

RWDI Project #1903305June 17, 2019

Pedestrian Wind Assessment |

REPORT

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REVERA RETIREMENT RESIDENCEPEDESTRIAN WIND ASSESSMENT

PROJECT #1903305

JUNE 17, 2019

SUBMITTED TO

Tony Ross

Principal

[email protected]

Montgomery Sisam Architects Inc.

197 Spadina Avenue, Suite 301

Toronto, ON

T: 416.364.8079 x287

SUBMITTED BY

Frank Kriksic, BES, CET, LEED AP

Microclimate Consultant / Principal

[email protected]

Kelly Baah, M.Eng., P.Eng.

Project Manager

[email protected]

Rowan Williams Davies & Irwin Inc. (RWDI)

600 Southgate Drive

Guelph, ON N1G 4P6

T: 519.823.1311 x 2261

F: 519.823.1316

BARRIE, ON

mailto:[email protected]





1. INTRODUCTION

Rowan Williams Davies & Irwin Inc. (RWDI) was retained by

Montgomery Sisam Architects Inc. to conduct a preliminary wind

study to assess the pedestrian wind conditions for the proposed

Revera Retirement Residence in Barrie, Ontario (see Image 1). A

wind assessment is required by the City of Barrie for the Zoning

By-Law Amendment as per their Terms of Reference.

This assessment is based on the following:

• a review of regional long-term meteorological data;

• design drawings received from Montgomery Sisam Architects

Inc. on May 10, 2019;

• wind-tunnel studies undertaken by RWDI for similar projects;

• our engineering judgement and knowledge of wind flows

around buildings1-3; and

• use of 3D software developed by RWDI (WindEstimator2) for

estimating the potential wind conditions around generalized

building forms.

This approach provides a screening-level estimation of potential

wind conditions. Conceptual wind control measures to improve

wind comfort are recommended, where necessary. Wind tunnel

testing may be required to quantify these wind conditions and

optimize the wind control measures presented herein.

Note that other wind issues such as those related to wind loads,

snow accumulation and loading, door operability, etc., are not

considered within the scope of this assessment.

2

1. H. Wu and F. Kriksic (2012). “Designing for Pedestrian Comfort in Response to Local Climate”, Journal of Wind Engineering and Industrial Aerodynamics, vol.104-106, pp.397-407.

2. H. Wu, C.J. Williams, H.A. Baker and W.F. Waechter (2004), “Knowledge-based Desk-Top Analysis of Pedestrian Wind Conditions”, ASCE Structure Congress 2004, Nashville, Tennessee.

3. C.J. Williams, H. Wu, W.F. Waechter and H.A. Baker (1999), “Experience with Remedial Solutions to Control Pedestrian Wind Problems”, 10th International Conference on Wind Engineering, Copenhagen, Denmark.

Image 1: Proposed Development – West Elevation



2. BUILDING AND SITE INFORMATION

The proposed development is located at the southeast corner of

the intersection of Owen St. and Collier St. (see Image 2). The site

is currently occupied by several low-rise buildings and an empty

lot. The site is surrounded by dense low-rise buildings and

parking lots in all directions, with taller buildings a block away to

the northeast and east and to distant south-southwest. Lake

Simcoe is located to the southeast though east.

The proposed development includes a15-storey L-shaped tower

(see Images 1, 3 and 4). Pedestrian areas include building

entrances, public sidewalks, exterior courtyard, terraces at Level

4 and outdoor dining terraces at Levels 2, 3 and 15.

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Image 4: View from Collier & Owen StreetsImage 2: Aerial View of Existing Site and Surrounding (Courtesy of GoogleTM Earth)

Ow

en St

Dunlop St E

Collier St

Image 3: Site Plan



3. LOCAL WIND CLIMATE

4

Springwater Barrie Airpark

Borden Airport

Lake Simcoe Regional Airport

Site

Wind records used in wind comfort assessments are typically

measured at airports in open fields for a long term and with high

data quality. They are often used as a reference of wind climate

for building projects in the surrounding area.

Wind data were not available at Springwater Barrie Airpark,

which is closest to the project site (see Image 5). Instead, data

from two airports in the area (Borden Airport and Lake Simcoe

Regional Airport) were analyzed to determine the local wind

directionality.

Wind statistics recorded at these two airports were analyzed for

the summer (May through September) and winter (October

through April) seasons. The seasonal data are presented in the

form of wind roses in Image 6, where the sectors show the

frequency of winds blowing from different directions and colours

indicate different speed ranges.

Image 5: Map of Site and Nearby Airport (photo credit: GoogleTM Earth)



3. LOCAL WIND CLIMATE

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At Borden Airport, winds are from the southeast through west to

north directions in both seasons. Strong winds of speeds greater

than 30 km/h (yellow and red bands in Image 6) occur more

often in the winter than in the summer and they are primarily

from the southwesterly and westerly directions.

Winds at Lake Simcoe Regional Airport are most frequent from

the west through northwest directions in both the summer and

winter seasons. The southeast winds are relatively frequent in

the summer and east winds in the winter, but they are of lower

wind speeds.

The difference in wind directions is primarily caused by local

topographies and their locations relative to the lakes in the area.

Given the site location, it is our opinion that winds at the project

site would be most frequent from the westerly directions

(including northwest and southwest) throughout the year, with

the secondary winds from the southeast and east directions.

Wind Speed (km/h)

Probability (%) Summer Winter

Calm 4.1 2.5

1-10 31.6 19.3

11-20 44.9 40.4

21-30 15.5 23.9

31-40 3.1 9.7

>40 0.8 4.1

Summer (May – October) Winter (November – April)

Summer (May – October) Winter (November – April)

Borden Airport (2000-2016)

Lake Simcoe Regional Airport (2003-2016)

Image 6: Directional Distribution of Winds Recorded at Two Local Airports



4. PEDESTRIAN WIND CRITERIA

The pedestrian wind criteria used in the current study are based

on those referenced in the City of Barrie’s Terms of Reference.

The criteria are outlined below.

4.1 Pedestrian Safety

Pedestrian safety is associated with excessive gust wind speeds

that can adversely affect a pedestrian’s balance and footing. If

strong winds that can affect a person’s balance (90 km/h) occur

more than 0.1% of the time or 9 hours per year, the wind

conditions are considered severe.

4.2 Pedestrian Comfort

Sitting (≤ 10 km/h): Calm or light breezes desired for outdoor

seating areas where one can read a paper without having it

blown away.

Standing (≤ 15 km/h): Gentle breezes suitable for main building

entrances and bus stops.

Walking (≤ 20 km/h): Relatively high speeds that can be

tolerated if one’s objective is to walk, run or cycle without

lingering.

Uncomfortable: None of the comfort categories are met.

Wind conditions are considered suitable for sitting, standing or

walking if the associated mean wind speeds are expected for at

least four out of five days (80% of the time). Wind control

measures are typically required at locations where winds are

rated as uncomfortable or they exceed the wind safety criterion.

Note that these wind speeds are assessed at the pedestrian

height (i.e., 1.5 m above grade or the concerned floor level),

typically lower than those recorded in the airport (10 m height

and open terrain).

These criteria for wind forces represent average wind tolerance.

They are sometimes subjective and regional differences in wind

climate and thermal conditions as well as variations in age,

health, clothing, etc. can also affect people's perception of the

wind climate.

For the current development, wind speeds comfortable for

walking are appropriate for sidewalks and lower wind speeds

comfortable for standing are required for building entrances

where pedestrians may linger. Wind speeds comfortable for

sitting are appropriate for outdoor dining terraces and roof

terrace during the summer, when these areas will be mainly

used.

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5.1 Background

Predicting wind speeds and occurrence frequencies is

complicated. It involves building geometry, orientation, position

and height of surrounding buildings, upstream terrain and the

local wind climate. Over the years, RWDI has conducted

thousands of wind-tunnel model studies regarding pedestrian

wind conditions around buildings, yielding a broad knowledge

base. This knowledge has been incorporated into RWDI’s

proprietary software that allows, in many situations, for a

screening-level numerical estimation of pedestrian wind

conditions without wind tunnel testing.

Since the surrounding buildings are shorter than the proposed

project, the proposed building will be fully exposed to winds

from all directions. Taller buildings tend to intercept the stronger

winds at higher elevations and redirect them to the ground level.

Such a Downwashing Flow (see Image 7a) is the main cause for

increased wind activity around taller buildings at the grade level.

When oblique winds are deflected down by a building, a

localized increase in wind activity or Corner Acceleration can be

expected around the downwind building corner at pedestrian

level (see Image 7b). If these building/wind combinations occur

for prevailing winds, there is a greater potential for increased

wind activity.

Building setbacks and podiums will reduce the direct impact of

downwashing wind flows at grade (see Image 7c); however,

higher wind activities are expected on the podium itself.

Given the local wind climate and the building design, it is

expected that the wind safety criteria to be met at all locations

on and around the development. Detailed discussions on the

potential wind conditions at key pedestrian areas are provided in

the following sections.

5. PEDESTRIAN WIND CONDITIONS

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Image 7: General Wind Flow Patterns around Taller Buildings

a) Downwashing Flow b) Corner Acceleration

c) Podium Reduces Impact of Downwashing



5.2 Existing Wind Conditions

The existing wind conditions on-site are likely to be comfortable

for sitting or standing during the summer and walking during the

winter. No wind safety exceedance is expected on and around

the site for the existing configuration.

5.3 Proposed Wind Conditions

5.3.1 Building Entrances

The proposed building will be exposed to the prevailing

southwesterly through northwesterly winds, which accelerate

down the west façade. The tower setback on the west side at

Level 4 is a positive design feature that will help to keep these

winds away from the Level 0 entrance on Owen St. (A1 in Image

8). This entrance is also recessed from the building façade and

has a vestibule, both of which provide a sheltered area for

pedestrians during windy days and should be retained.

The retail/public bistro and main entrance along the north

façade (A2 and A3 in Image 9) is located in a recessed area,

which is a positive design feature for favourable wind speeds.

Wind conditions at these two entrances are expected to be

comfortable for standing throughout the year, which is

appropriate for the intended use.


8

Image 8: Level 0 Floor Plan

Image 9: Level 1 Floor Plan

A1

B1

B2

A2

A3



Two exits are marked with a blue triangle as B1 and B2 in Images

8 and 9 respectively. Being on the east façade, exit B1is

protected from the more dominant prevailing westerly winds by

the building itself. It will be exposed to the easterly and

southeasterly winds; however, these winds are not very strong

and are infrequent compared to the westerly winds. Appropriate

wind conditions are expected at these side entrances and exits

throughout the year.

5.3.2 Sidewalks

Pedestrians on sidewalks are active and relatively high wind

speeds comfortable for walking are acceptable. This criterion is

expected to be met on the sidewalks adjacent to the proposed

development throughout the year. This is a result of the tower

setback on the west side at Level 4, which helps to keep winds

away from the ground. Typical street trees along Owen St. and at

the northwest corner of the development would be expected to

further improve the conditions during the months when the

trees have foliage.

Wind speeds at the northwest building corner (in the vicinity of

exit B2 in Image 9) are expected to be uncomfortable during the

winter. We recommend including coniferous or marcescant

landscaping at this building corner and/or installing a canopy

above exit B2. Examples of these wind control strategies are

shown in Image 10.


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Image 10: Examples Canopies and Landscaping



5.3.3 Outdoor Terraces and Courtyard

The dining terraces at Levels 2 and 3 (see Image 11) will be

protected by the building itself from the westerly winds and, to

some extent, by the existing surrounding buildings from the

southeasterly summer winds. There will be some exposure to

the southeasterly winds after they are directed down the south

building façade, but these terraces will be protected by the ones

overhead providing conditions that should be acceptable for

sitting or standing in the summer.

The Level 1 courtyard will also be protected from the most

dominant westerly winds but will be exposed to southeasterly

winds downwashing off the building façade above. However, the

design incorporates some very positive features with the tower

setback at Level 4 (which will help provide protection from these

downwashing winds) and the perimeter wind screen. Summer

conditions in this courtyard should be comfortable for standing.

If desired, overhead trellises could be added into the courtyard

to provide localized areas of additional wind protection to

achieve sitting conditions. Examples of these wind control

strategies are shown in Image 13.


10

Image 11: Terraces and Courtyard

Level 2 & 3 Terraces

Level 1 Courtyard



5.3.4 Level 4 Terraces

The terraces at Level 4 on the east side of the building (C1 and

C2 in Image 11) will be similar to the courtyard in that they will

be protected by the building itself from the dominant westerly

winds but vulnerable to the southeasterly winds. Even with this,

the conditions in this area are expected to be comfortable for

standing or strolling in summer. If it is desirable to further

improve these conditions then overheard protection in the form

of canopies or trellises are recommended.

The Level 4 terraces overlooking Owen Street (along the west

façade of the building – C3 in Image 11) will be exposed to strong

westerly winds downwashing along the west façade of the tower

likely creating conditions that will be suitable for strolling or

walking in the summer and uncomfortable in the winter. These

conditions are less than desirable for private terraces, especially

in the summer, and would require overhead protection from

downwashing winds in the form of canopies or trellises.

Examples are shown in Images 10 and 13.


11

Image 12: Level 4 Terraces

C1

C2

C3



5.3.5 Level 15 Terrace

The terrace on the east side of Level 15 (see Image 13) will be

well protected from the dominant westerly winds but exposed to

southeasterly winds. Wind conditions on this terrace are

expected to be higher than desired for passive activities during

the summer.

We recommend to install a 2 m tall guardrail / screen along the

eastern edge of the terrace which could be glass to preserve the

views. Examples of these wind control strategies are shown in

Image 13.


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Image 12: Level 14 Roof PlanImage 14: Level 15 Plan

Terrace

Image 13: Examples of Tall Parapets and Trellises



6. SUMMARY

Wind conditions on and around the proposed Revera Retirement

Residence in Barrie, ON are discussed in this report and our

assessment is based on the local wind climate, surrounding

buildings and our past experience with wind tunnel testing of

similar buildings.

The proposed development has several positive design features

such as tower setbacks on the west side at Level 4, and recessed

entrances and vestibules at the main entrances. Suitable wind

conditions are predicted at all main entrances and most of the

perimeter sidewalks. Exceptions include the northwest corner of

the building, the Level 4 terraces and the Level 15 Dining

Terrace.

Conceptual wind control measures are described for these

windier areas in an effort to improve the wind conditions to

more appropriate levels. Wind tunnel testing may be required at

a later design stage, as per the City’s Terms of Reference, to

quantify these wind conditions and optimize the wind control

measures presented herein.

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7. APPLICABILITY OF RESULTS

The assessment presented in this report for the Revera

Retirement Residence are based on the design drawings and

documents received from Montgomery Sisam Architects Inc. on

June 11, 2019.

In the event of any significant changes to the design,

construction or operation of the building or addition of

surroundings in the future, RWDI could provide an assessment

of their impact on the pedestrian wind conditions discussed in

this report. It is the responsibility of others to contact RWDI to

initiate this process.

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