Pedestrian Level Wind Study - Vancouver

127 Walgreen Road, Ottawa, Ontario K0A 1L0

(613) 836‐0934 www.gradientwind.com

Pedestrian Level Wind Study Including Thermal Effects

1133 Melville Street

Vancouver, British Columbia

REPORT: GWE15‐081‐PLW‐2017

Prepared For:

Carlo Timpano Director, Development Oxford Properties Group 200 Bay Street, Suite 900 Toronto, Ontario M5J 2J2

Prepared By:

Justin Ferraro, Partner Vincent Ferraro, M.Eng., P.Eng., Managing Principal

August 25, 2017

Oxford Properties Group – James KM Cheng Architects Inc.

1133 Melville Street, Vancouver: Pedestrian Level Wind Study + Thermal Effects ii

EXECUTIVE SUMMARY

This report describes a pedestrian level wind study undertaken for a proposed mixed‐use office building

located at 1133 Melville Street in Vancouver, British Columbia. This work was performed in accordance

with the terms of GWE proposal #17‐074P, dated April 3, 2017, and was based on wind tunnel

measurements of wind speeds, combined with a statistical model of the Vancouver area wind climate, to

assess pedestrian comfort and safety at grade level and over multiple elevated terraces. The scope of

work also includes consideration of thermal comfort, which represents a refinement of wind comfort

due solely to mechanical effects.

A complete summary of the predicted wind conditions based on mechanical effects is provided in

Sections 5.1 and 5.2 of this report, and illustrated in Figures 2A‐5B (following the main text). Thermal

effects of wind cooling and solar heating are presented in Section 5.3. The results of the analyses indicate

the following:

1. Wind conditions at grade are found to be calm and suitable for the intended uses over the entire

site without the need for mitigation. The thermal influences serve to extend periods of

pedestrian comfort.

2. Conditions within the large terrace on Level 11 mimic those at grade with comfortable

conditions existing for large proportions of the time, including consideration of thermal effects.

3. Conditions on the remaining large terraces at Levels 16, 18, 26, and the roof deck become

somewhat windier at these levels due to their exposure to stronger winds. However, wind

comfort is increased because of exposure to more sunlight. Nonetheless, the terrace on Level

18, as well as the east terrace on Level 26, would benefit from the introduction of perimeter

wind barriers with a height of 1.8 m above the walking surface to ensure conditions will be

suitable for sitting during the typical use period, if desired.

4. In global terms, pedestrian comfort conditions are found to be acceptable over the entire site

based on the mechanical effects of wind, which are improved when thermal effects are added

into the analysis.

5. However, the wind conditions over the site are sufficiently breezy so that when combined with

the effects of sun and shadow conditions remain comfortable for prolonged exposure.


1133 Melville Street, Vancouver: Pedestrian Level Wind Study + Thermal Effects iii

TABLE OF CONTENTS

1. INTRODUCTION 1

2. TERMS OF REFERENCE 1

3. OBJECTIVES 2

4. STUDY METHODOLOGY 2

4.1 Wind Tunnel Context Modelling 3 4.2 Wind Speed Measurements 3 4.3 Historical Wind Data Analysis 4 4.4 Pedestrian Comfort Guidelines – Mechanical Effects of Wind 6 4.5 Thermal Effects Background 9 4.5.1 Sun‐Shade Modelling 10

5. RESULTS 11

5.1 Pedestrian Comfort Suitability – Mechanical Effects of Wind 11 5.2 Summary of Significant Findings – Mechanical Effects of Wind 28 5.3 Results of Thermal Assessment 29 5.3.1 Thermal Comfort by Zones 33

6. SUMMARY AND RECOMMENDATIONS 37

MODEL PHOTOGRAPHS FIGURES APPENDICES Appendix A – Wind Tunnel Simulation of the Natural Wind Appendix B – Pedestrian Level Wind Measurement Methodology Appendix C – Shadow Renderings


1133 Melville Street, Vancouver: Pedestrian Level Wind Study + Thermal Effects 1

1. INTRODUCTION

Gradient Wind Engineering Inc. (GWE) was retained by Oxford Properties Group to undertake a

pedestrian wind comfort study for a proposed mixed‐use office development located at 1133 Melville

Street in Vancouver, British Columbia. The complete scope of work within our mandate includes the

study of pedestrian level winds, as well as a preliminary thermal comfort study for representative times

of the seasons. This report summarizes the methodology, results, and recommendations related to the

pedestrian level wind study, including thermal effects. Our work is based on industry standard wind

tunnel testing and analysis procedures, architectural drawings provided by James KM Cheng Architects

Inc. in May and August 2017, and approved future building massing information obtained from the City

of Vancouver, as well as recent site imagery.

2. TERMS OF REFERENCE

The focus of this pedestrian level wind (PLW) study is the proposed mixed‐use office development located

at 1133 Melville Street in Vancouver. The development features a thirty‐six (36) storey office building,

including retail and restaurant spaces on the ground floor, as well as a plaza. The building design is a 4‐box

scheme enclosed with glass cladding, with the third box from grade rotated 6° counterclockwise in plan,

rising to a total maximum height of approximately 168 meters (m), or 550 feet, above grade. Additionally,

the development is served by five (5) levels of below‐grade parking with access provided at its northwest

corner from the laneway on the north side of the site. In this report, Melville Street is taken as project

south. The building also includes office decks (terraces) on various levels, as described below.

Box 1 ‐ Level 1, retail terrace along the north and east elevations (103.49 square meters or m2) +

restaurant terrace along the south elevation (111.95 m2) ‐ Level 3, office terrace cantilevered from the east elevation (52.95 m2) ‐ Level 4, office terrace along the north elevation (164.35 m2) ‐ Level 11, continuous office terrace along the west, south, and east elevations (558.90 m2)

Box 2 ‐ Level 16, continuous office terrace along the north, east, and south elevations (379.04 m2)

Box 3 ‐ Level 18, continuous office terrace along the north and west elevations (382.76 m2) ‐ Level 26, office terraces along the south elevation (46.17 m2) and west elevation (40.41 m2)

Box 4 ‐ Roof Level, large office terrace (674.48 m2)



Entrances to the retail and bicycle parking spaces are located along the north elevation, while access to

the residential lobby is provided at the southeast corner of the building. There is no pedestrian access

along the west elevation. The landscaped plaza, which extends the full length of the east elevation with a

short return along the south elevation, includes a winding walkway connecting Melville Street with the

laneway to the north.

The area surrounding the study site is characterized from the east clockwise to northwest by a dense urban

mix of high‐rise buildings. The remaining compass azimuth is characterized by an open exposure. Grade

level pedestrian areas considered in this study include nearby sidewalks, the laneway along the north side

of the development, building access points, the noted terraces and plaza, as well as the existing plaza to

the immediate north, and the existing plazas at the southwest and northwest corners of Melville Street

and Thurlow Avenue. Wind comfort is also quantitatively evaluated on the terraces serving Levels 11, 18,

and the roof deck.

Figure 1 illustrates the study site and surrounding context, while Photographs 1 through 4 depict the wind

tunnel model used to conduct the study. Assessment of thermal comfort is limited to the outdoor patio

and plaza areas, as well as the noted terraces and pedestrian pathways within the property line.

3. OBJECTIVES

The principal objectives of this study are to: (i) determine pedestrian level comfort and safety conditions

at key outdoor areas, including thermal effects; (ii) identify areas where future wind conditions may

interfere with the intended uses of outdoor spaces; and (iii) recommend suitable mitigation measures,

where required.

4. STUDY METHODOLOGY

The approach followed to quantify pedestrian wind conditions over the site is based on wind tunnel

measurements of wind speeds at selected locations on a reduced scale physical model, meteorological

analysis of the Vancouver wind climate, and synthesis of wind tunnel data with industry accepted

comfort guidelines. The following sections describe the analysis procedures, including a discussion of

the pedestrian comfort guidelines.



4.1 Wind Tunnel Context Modelling

A PLW assessment was performed to determine the influence of local winds on the proposed

development. A physical model, illustrated in Photographs 1 through 4 (following the main text), of the

development and relevant surroundings was constructed at a scale of 1:400. The wind tunnel model

includes all existing buildings and approved future developments (if applicable) within a full‐scale

diameter of 840 m. The general concept and approach to wind tunnel modelling is to provide building

and topographic detail in the immediate vicinity of the study site on the surrounding model, and to rely

on a length of wind tunnel upwind of the model to develop wind properties consistent with known

turbulent intensity profiles that represent the surrounding terrain. An industry standard practice is to

omit trees, vegetation and other existing and planned landscape elements from the wind tunnel model

due to the difficulty of providing accurate seasonal representation of vegetation, and because the

approach produces slightly less conservative results.

4.2 Wind Speed Measurements

The PLW assessment was performed by testing a total of sixty (60) wind sensor locations on the scale

model in GWE’s wind tunnel. Of the 60 sensor locations, forty‐seven (47) were placed at the ground

level, while the remaining thirteen (13) sensors were divided between the terraces on Levels 11, 18, and

the Roof. Wind speed measurements were performed at each of the noted sensors for 36 wind

directions at 10° intervals. Sensor locations used to investigate wind conditions are illustrated in Figures

2A through 5B (following the main text). Greater detail concerning the theory behind wind speed

measurements is provided in Appendices A and B, while the raw wind tunnel data will be made available

upon request.

Mean and peak wind speed values for each location and wind direction were calculated from real‐time

pressure measurements, recorded at a sample rate of approximately 500 samples per second, and taken

over a 60‐second time period. This period at model‐scale corresponds approximately to one hour in full‐

scale, which matches the time frame of full‐scale meteorological observations. Measured mean and gust

wind speeds at all noted sensor locations were referenced to the wind speed measured near the ceiling

of the wind tunnel to generate mean and peak wind speed ratios. Ceiling height in the wind tunnel

represents the depth of the boundary layer of wind flowing over the Earth’s surface, referred to as the

gradient height. Within this boundary layer, mean wind speed increases up to the gradient height and

remains constant thereafter.



4.3 Historical Wind Data Analysis

A statistical model for winds in Vancouver was developed from approximately 40 years (1973‐2013) of

hourly meteorological wind data recorded at Vancouver International Airport. Wind speed and direction

data were analyzed for each month of the year in order to: (i) determine the statistically prominent wind

directions and corresponding speeds; and (ii) characterize similarities between monthly weather

patterns. Based on this portion of the analysis, the four seasons are represented by grouping data from

consecutive months based on similarity of weather patterns, and not according to the traditional

calendar method.

The statistical model of the Vancouver wind climate, which indicates the directional character of local

winds on a seasonal basis, is illustrated on the following page. The plots illustrate seasonal distribution

of wind speeds and directions measured at Vancouver International Airport in meters per second (m/s).

Probabilities of occurrence of different wind speeds are represented as stacked polar bars in sixteen (16)

azimuth divisions. The radial direction represents the percentage of occurrence of each wind speed and

corresponding direction during the 40‐year measurement period. The preferred wind speeds and

directions can be identified as the length of the bar where the given bar has the largest length. For

Vancouver, the most common winds occur for easterly directions, followed by those from the west. The

most common wind speeds are below 10 m/s, or 36 kilometers per hour (km/h), while the most

prominent wind direction for higher wind speeds originates from the west during the spring months.

The directional preference and relative magnitude of wind speed changes somewhat from season to

season. By convention in microclimate studies, wind direction refers to the wind origin (e.g., a north

wind blows from north to south).



SEASONAL DISTRIBUTION OF WINDS FOR VARIOUS PROBABILITIES VANCOUVER INTERNATIONAL AIRPORT, VANCOUVER, BRITISH COLUMBIA

NOTES:

1. Radial distances indicate percentage of time of wind events. 2. Mean hourly wind speeds in m/s measured at 10 m above the ground. 3. Apply a factor of 3.6 to convert m/s to km/h (e.g., 10 m/s is equivalent to 36 km/h).



4.4 Pedestrian Comfort Guidelines – Mechanical Effects of Wind

Pedestrian comfort guidelines are commonly based on mechanical wind effects without consideration

of other meteorological conditions (i.e. temperature, sun exposure, cloud cover, humidity). The

guidelines provide an assessment of comfort, assuming that pedestrians are appropriately dressed for a

specified outdoor activity during any given season. Five pedestrian comfort classes and corresponding

gust wind speed ranges are used to assess pedestrian comfort, which include: (i) Sitting; (ii) Standing;

(iii) Walking; (iv) Uncomfortable; and (v) Dangerous. More specifically, the comfort classes, associated

wind speed ranges, and limiting guidelines are summarized as follows:

(i) Sitting – Wind speeds at or below 14 km/h (i.e., 0 ‐ 14 km/h) occurring at least 80% of the time

would be considered acceptable for sedentary activities, including sitting.

(ii) Standing – Wind speeds at or below 22 km/h (i.e., 0 ‐ 22 km/h) occurring at least 80% of the

time are acceptable for activities such as standing, strolling or more vigorous activities.

(iii) Walking – Wind speeds at or below 30 km/h (i.e., 0 ‐ 30 km/h) occurring at least 80% of the time

are acceptable for walking or more vigorous activities.

(iv) Uncomfortable – Uncomfortable conditions are characterized by predicted values that fall

below the 80% target for walking. Brisk walking and exercise, such as jogging, would be

acceptable for moderate excesses of this criterion.

(v) Dangerous – Wind speeds greater than or equal to 90 km/h occurring at least 0.1% of the time

are classified as dangerous. From calculations of stability, it can be shown that gust wind speeds

of 90 km/h would be the approximate threshold wind speed that would cause an average elderly

person in good health to fall.

The wind speeds associated with the above categories are gust wind speeds. Gust speeds are used in

the guidelines because people tend to be more sensitive to wind gusts than to steady winds for lower

wind speed ranges. For strong winds approaching dangerous levels, this effect is less important because

the mean wind can also cause problems for pedestrians. The gust speed ranges are selected based on

‘The Beaufort Scale’ (presented on the following page), which describes the effects of forces produced

by varying wind speed levels on objects.



THE BEAUFORT SCALE

Number Description Wind Speed

(km/h) Description

2 Light Breeze 4‐8 Wind felt on faces.

3 Gentle Breeze 8‐15 Leaves and small twigs in constant motion; Wind extends light flags.

4 Moderate Breeze 15‐22 Wind raises dust and loose paper; Small branches are moved.

5 Fresh Breeze 22‐30 Small trees in leaf begin to sway.

6 Strong Breeze 30‐40 Large branches in motion; Whistling heard in electrical wires; Umbrellas used with difficulty.

7 Moderate Gale 40‐50 Whole trees in motion; Inconvenient walking against wind.

8 Gale 50‐60 Breaks twigs off trees; Generally impedes progress.

Experience and research on people’s perception of mechanical wind effects has shown that if, for

instance, wind speeds of 14 km/h were exceeded for more than 20% of the time most pedestrians would

judge that location to be too windy for sitting or more sedentary activities. Similarly, if 30 km/h at a

location were exceeded for more than 20% of the time walking or less vigorous activities would be

considered uncomfortable. As most of these guidelines are based on subjective reactions of a population

to wind forces, their application is partly based on experience and judgment.

Once the pedestrian wind speed predictions have been established at tested locations, the assessment

of pedestrian comfort involves determining the suitability of the predicted wind conditions for their

associated spaces. This step involves comparing the predicted comfort class to the desired comfort class,

which is dictated by the location type. An overview of common pedestrian location types and their

desired comfort classes are summarized below.



DESIRED PEDESTRIAN COMFORT CLASSES FOR VARIOUS LOCATION TYPES

Location Types Desired Comfort Classes

Primary Building Entrance Standing

Secondary Building Entrance Walking

Public Sidewalk / Pedestrian Walkway Walking

Outdoor Amenity Space / Terrace Sitting / Standing

Café / Patio / Bench / Garden Sitting / Standing

Public Transit Stop Standing

Public Park Sitting / Standing

Garage / Service Entrance Walking

Laneway / Loading Zone / Drop‐Off Zone Walking

Following the comparison, the location is assigned a descriptor that indicates the suitability of the

location for its intended use. The suitability descriptors are summarized as follows:

Acceptable: The predicted wind conditions are suitable for the intended uses of the associated

outdoor spaces without the need for mitigation.

Acceptable with Mitigation: The predicted wind conditions are not acceptable for the intended

use of a space; however, following the implementation of typical mitigation measures, the wind

conditions are expected to satisfy the required comfort guidelines.

Mitigation Testing Recommended: The effectiveness of typical mitigation measures is

uncertain, and additional wind tunnel testing is recommended to explore other options and to

ensure compliance with the comfort guidelines.

Incompatible: The predicted wind conditions will interfere with the comfortable and/or safe use

of a space, and cannot be feasibly mitigated to acceptable levels.



4.5 Thermal Effects Background

Thermal comfort is a state of being whereby the human body perceives itself to be in thermal

equilibrium with its surroundings. In this steady‐state condition, the body is able to function safely and

comfortably within a range of core body temperatures between 36.5 degrees Celsius (°C) to 38 °C,

depending on activity.

For the purpose of this work, the human body is an engine that consumes fuel and generates energy

necessary to perform essential functions and external work. The rate at which the body generates

energy is referred to as the metabolic rate (measured in Watts per square metre of body surface area,

W/m2), which depends on activity level and external temperature. During normal sedentary activities, a

typical metabolic rate for a human is approximately 60 W/m2 of body surface area, increasing to as much

as 180 W/m2 during heavy work or exercise. The body’s self‐control mechanisms, which protect against

significant deviations of the core body temperature, include perspiring when the body is too hot and

shivering when the body is too cold. When the instinctive reactions are insufficient to restore comfort,

the individual may take action by increasing or decreasing the amount of clothing, or changing

environments.

Thermal comfort is influenced by a variety of physiological, psychological, and environmental factors.

Emotional states of mind are well known to affect perception and influence an individual’s response to

the environment. Other factors within a person’s control are clothing and activity levels. External factors

that control the heat exchange between the body and its environment, and therefore influence thermal

comfort, include: dry bulb temperature, direct and indirect solar radiation, cloud cover, wind speed, and

relative humidity.

It is assumed that a person is suitably dressed for the season. In this regard, the philosophy of the

approach is based on the concept of adaptive response. Within the context of this study, this term means

that thermal comfort exists either when the environmental conditions meet ideal comfort guidelines, or

when factors, within the control of the individual, can be easily changed to create thermal comfort. For

instance, a person who is cold may become comfortable in an outdoor setting by putting on a jacket,

while someone who is hot in direct sunlight can alter his/her environment to become comfortable by

moving to a shady location. Hence, the factors for consideration in this study include: (i) mechanical

wind effects; (ii) temperature; and (iii) solar effects on outdoor comfort. Relative humidity is assumed

to be in the range of 40% to 70% but is otherwise not included in the analysis.



4.5.1 Sun‐Shade Modelling

In order to determine the influence of the sun on thermal comfort, sun‐shadow patterns over the site

were obtained by computer modelling. The principal solar days, two equinox (March 21 and September

21) and two solstice dates (June 21 and December 21), were simulated for approximately 8 hours per

day on average – more during the summer and less during the winter. The latitude of the site, which

determines the maximum altitude that the sun reaches above the horizon is taken to be 49° 17’ 13’’

(degrees, minutes, seconds) North. Figures C1 to C37 in Appendix C illustrate sun‐shadow patterns over

the site. Table C1 cross‐references time of day, month, and figure number.

The sun‐shade assessment was necessary to determine what proportion of the time various areas of the

site spend in sunlight and shade, thereby providing input into the thermal analysis of the outdoor space.

It should be noted that all times indicated are in pacific daylight time (PDT) and that no time shifts have

been used to represent daylight saving time.



5. RESULTS

5.1 Pedestrian Comfort Suitability – Mechanical Effects of Wind

Tables 1 through 16, beginning on the following page, provide a summary of seasonal comfort

predictions for each of the 60 sensor locations. The tables indicate the predicted percentages of time

that wind speeds will fall into the ranges defined in the guidelines. Pedestrian comfort is determined by

the percentage of time wind speeds at each sensor location will fall within the stated ranges. A higher

numerical value equates to a greater percentage of time that wind speeds will be lower and

correspondingly more comfortable wind conditions.

The predicted values within each table are followed by columns containing a suitability assessment that

includes the predicted comfort class (i.e., sitting, standing, walking, etc.), the predicted safety status

(i.e., a percentage less than 0.1% is considered safe), the location type, the target comfort class, and a

suitability descriptor. The predicted comfort class is determined by the predicted wind speed range

percentages, while the location type and target comfort class are determined from the sensor placement

on the wind tunnel model, as well as by the intended use of the represented location. The suitability

descriptor is assigned based on the relationship between the predicted comfort class (for each seasonal

period) and the target comfort class.

Following Tables 1 through 16, the most significant findings of the PLW study are summarized. To assist

with understanding and interpretation, predicted conditions for the planned development are also

illustrated in colour‐coded format in Figures 2A through 5B. The colour codes indicate the predicted

comfort class at each tested sensor location, according to the tabulated results. Conditions suitable for

sitting and standing are represented by the colours green and yellow, respectively.

Measured mean and gust velocity ratios, which constitutes the raw data upon which the results are

based, will be made available upon request.



TABLE 1: SUMMARY OF PEDESTRIAN COMFORT & SAFETY

Activity Type Sitting Standing Walking Safety Predicted Comfort Class

Location Type

Desired Comfort Class

Suitability Wind Speed Range (km/h) 14 22 30 ≥ 90

Guideline (% of Time) ≥ 80 < 0.1

Sensor #1

Spring 84 97 99 0.00 Sitting

Existing Plaza

Standing Acceptable Summer 90 99 100 0.00 Sitting

Autumn 83 95 98 0.00 Sitting

Winter 83 95 99 0.00 Sitting

Sensor #2


Existing Plaza




Sensor #3


Existing Plaza




Sensor #4


Existing Plaza




1133 MELVILLE STREET, VANCOUVER: PLW SENSOR LOCATIONS





Location Type




Sensor #5


Existing Plaza




Sensor #6


Existing Plaza




Sensor #7


Existing Plaza




Sensor #8


Existing Plaza









Location Type




Sensor #9


Existing Plaza




Sensor #10


Pedestrian Walkway

Walking Acceptable Summer 90 98 100 0.00 Sitting



Sensor #11


Pedestrian Walkway




Sensor #12


Sidewalk Walking Acceptable Summer 89 98 99 0.00 Sitting








Location Type




Sensor #13





Sensor #14





Sensor #15





Sensor #16


Laneway Walking Acceptable Summer 86 96 99 0.00 Sitting








Location Type




Sensor #17


Stairwell Exit




Sensor #18


Building Services




Sensor #19


Building Services




Sensor #20


Building Services









Location Type




Sensor #21





Sensor #22





Sensor #23





Sensor #24










Location Type




Sensor #25





Sensor #26





Sensor #27


Green Space




Sensor #28


Plaza Walking Acceptable Summer 97 100 100 0.00 Sitting








Location Type




Sensor #29


Pathway Walking Acceptable Summer 90 98 100 0.00 Sitting



Sensor #30





Sensor #31





Sensor #32










Location Type




Sensor #33

Spring 87 98 100 0.00 Sitting Existing SunLife Plaza




Sensor #34





Sensor #35

Spring 77 92 97 0.00 Standing




Sensor #36


Sidewalk Walking Acceptable Summer 78 96 99 0.00 Standing

Autumn 77 92 97 0.01 Standing

Winter 78 92 97 0.00 Standing






Location Type




Sensor #37





Sensor #38





Sensor #39





Sensor #40


Terrace / Sidewalk

Sitting Acceptable Summer 91 99 100 0.00 Sitting








Location Type




Sensor #41


Terrace / Sidewalk




Sensor #42


Terrace / Sidewalk




Sensor #43










Location Type




Sensor #44





Sensor #45

Spring 86 97 99 0.00 Sitting Main Lobby

Entrance Standing Acceptable

Summer 90 98 100 0.00 Sitting



Sensor #46


Plaza Sitting Acceptable Summer 89 98 100 0.00 Sitting








Location Type




Sensor #47


Terrace Level 11

Sitting During Summer

Acceptable Summer 88 97 100 0.00 Sitting



Sensor #48


Terrace Level 11





Sensor #49


Terrace Level 11





Sensor #50


Terrace Level 18


Acceptable with

Mitigation

Summer 65 86 95 0.00 Standing








Location Type




Sensor #51


Terrace Level 18





Sensor #52


Terrace Level 18





Sensor #53


Terrace Level 18





Sensor #54


Terrace Level 18










Location Type




Sensor #55


Terrace Roof Deck





Sensor #56


Terrace Roof Deck





Sensor #57


Terrace Roof Deck


Acceptable with

Mitigation









Location Type




Sensor #58


Terrace Roof Deck


Acceptable with

Mitigation




Sensor #59


Terrace Roof Deck


Acceptable with

Mitigation




Sensor #60


Terrace Roof Deck








5.2 Summary of Significant Findings – Mechanical Effects of Wind

Based on the analysis of the measured data, consideration of local climate data, and the suitability

descriptors provided in Tables 1 through 16 in Section 5.1, the mechanical effects of wind indicate the

following conditions:

1. Acceptable wind conditions, suited to the intended uses, are predicted to occur over all grade‐

level areas. In particular, all building access points will be suitable for sitting throughout the year.

The plaza area on the east side, represented by sensors 27‐31, 37, and 46, as well as the restaurant

terrace, represented by sensors 40‐42, will also be suitable for sitting throughout the year.

2. The main elevated outdoor areas / terraces that were quantitatively considered in this study are

situated on Levels 11 and 18, as well as atop the roof deck. The Level 11 terrace, represented by

sensors 47‐49, will be suitable for sitting throughout the year. Wind conditions within the

remaining terraces are mixed between sitting and standing. The Level 18 terrace, represented by

sensors 50‐54, will mostly be suitable for sitting during the summer season, except for the

northern‐most 25% of the area, which will be suitable for standing. Also, although conditions

within the roof deck, represented by sensors 55‐60, will be mostly suitable for standing, the areas

represented by sensors 55 and 60 remain suitable for sitting throughout the year.

3. For the terrace situated on Level 18, winds from the northeast and west reduce pedestrian

comfort. Calm conditions suitable for sitting during the typical use period, defined as late spring

through early autumn, can be achieved by introducing perimeter wind barriers with a height of

1.8 m above the walking surface.

4. Wind conditions within the terrace on Level 16 are predicted to be suitable for sitting from late

spring to early autumn, becoming suitable for standing, or better, during the remaining colder

months of the year.

5. Regarding the south terrace on Level 26, wind conditions are predicted to be suitable for sitting

during the summer season, becoming suitable for standing, or better, during the remaining three

colder seasons. Conditions within the east terrace are expected to be somewhat windier and

suitable for standing, or better, throughout the year. Therefore, for the east terrace, sitting

conditions during the summer season could be achieved with 1.8 m tall perimeter wind barriers.



6. Within the context of typical weather patterns, which exclude anomalous localized storm events

such as tornadoes and downbursts, no areas over the study site were found to experience wind

conditions that are considered unsafe.

5.3 Results of Thermal Assessment

The analysis of thermal comfort has been based on the combination of baseline data (i.e., wind speed,

temperature, sun exposure and cloud cover) obtained from the physical character at key pedestrian

areas, combined with meteorological data for Vancouver. Wind speed, temperature, solar data, and

cloud cover are integrated by using the basic research work performed by Steadman1, which is packaged

in the form of the Steadman equation of ‘Apparent Temperature’ (AT). Unlike the wind chill concept,

the AT equation includes the thermal exchanges of the human body with its surroundings, direct and

indirect solar radiation, and clothing levels. The AT equation calculates the apparent temperature

perceived by an individual in the outdoor environment under consideration. The AT matrix of

comfortable temperature is presented for sunny conditions in Table 17 and for full shade in Table 18 as

a function of wind speed and dry bulb temperature.

Highlighted on the AT grid are six (6) temperature ranges that define pedestrian comfort under sun and

shade conditions. The solid colour highlights (area ‘A’) define comfort levels for full sun (Table 17) or full

shade (Table 18) corresponding to sedentary activities. The dashed coloured lines corresponding to each

area (lines ‘B’ and ‘C’) represent acceptable comfort zones at higher levels of activity corresponding to

higher metabolic rates. The zones represented by areas A+B and A+B+C correspond to standing and

walking activities respectively. The trends in these figures indicate that more active individuals will

generate more heat and can tolerate colder temperatures. The zones of comfort are based on limited

research of human subjects2, augmented by in‐house experience.

The assessment of pedestrian comfort involves calculation of the Steadman AT for each hour of

meteorological data over a 10‐year period at each sensor location based on the recorded wind speed,

wind direction, dry bulb temperature, cloud cover, and sun exposure. The raw meteorological data

required for this step is obtained from the Vancouver International Airport for ten years between 2004

1 Steadman, Robert, G., A Universal Scale of Apparent Temperature, Journal of Climate and Applied Meteorology, 1984, Vol. 23 2 Lawson, T.V., Penwarden, A.D., The Effects of Wind on People In The Vicinity of Buildings, 4th Int’l Conf. Wind Effects on Buildings and Structures, 1976



and 2014. Filtering this data by the comfort guidelines in Tables 17 and 18 provides the frequency of

occurrences of comfort levels for sun, shade, and cloudy conditions.

Tables 17 and 18 also indicate the proportion, or percentage (%), of daylight hours during which

conditions are suitable for pedestrian activities under the assumption of ‘adaptive response’. In practical

terms, the results describe conditions that would be considered acceptable by an average population

provided there is a reasonable opportunity to modify one’s environment, which means one is able to

make a minor change to enlarge the comfort envelope. For instance, removing a sweater or moving from

shade to sun would qualify as changes that could easily be made by an individual to become more

comfortable.



TABLE 17: APPARENT TEMPERATURE (AT) GRID FOR FULL SUN OUTDOORS

Wind Speed (Top - km/h, Bottom - m/s)

0 4 7 11 14 18 22 25 29 32 36 40 43 47 50 54 km/h0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 m/s

-20 -20 -22 -23 -24 -26 -27 -29 -30 -31 -33 -34 -35 -37 -38 -39 -40-19 -19 -21 -22 -23 -25 -26 -28 -29 -30 -32 -33 -34 -35 -37 -38 -39-18 -18 -20 -21 -22 -24 -25 -27 -28 -29 -30 -32 -33 -34 -35 -37 -38-17 -17 -19 -20 -21 -23 -24 -25 -27 -28 -29 -31 -32 -33 -34 -35 -36-16 -16 -18 -19 -20 -22 -23 -24 -26 -27 -28 -29 -31 -32 -33 -34 -35-15 -15 -17 -18 -19 -21 -22 -23 -25 -26 -27 -28 -29 -31 -32 -33 -34-14 -14 -16 -17 -18 -20 -21 -22 -23 -25 -26 -27 -28 -29 -31 -32 -33-13 -13 -15 -16 -17 -19 -20 -21 -22 -24 -25 -26 -27 -28 -29 -30 -31-12 -12 -14 -15 -16 -18 -19 -20 -21 -22 -24 -25 -26 -27 -28 -29 -30

T -11 -11 -13 -14 -15 -16 -18 -19 -20 -21 -22 -24 -25 -26 -27 -28 -29-10 -10 -12 -13 -14 -15 -17 -18 -19 -20 -21 -22 -24 -25 -26 -27 -28

E -9 -9 -11 -12 -13 -14 -16 -17 -18 -19 -20 -21 -22 -23 -24 -25 -26-8 -8 -10 -11 -12 -13 -14 -16 -17 -18 -19 -20 -21 -22 -23 -24 -25

M -7 -7 -9 -10 -11 -12 -13 -15 -16 -17 -18 -19 -20 -21 -22 -23 -24-6 -6 -8 -9 -10 -11 -12 -13 -15 -16 -17 -18 -19 -20 -21 -22 -23

P -5 -5 -7 -8 -9 -10 -11 -12 -13 -15 -16 -17 -18 -19 -20 -20 -21-4 -4 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16 -17 -18 -19 -20

E -3 -3 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16 -17 -18 -19-2 -2 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16 -17 -18

R -1 -1 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -15 -160 0 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -13 -14 -15

A 1 1 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -11 -12 -13 -142 2 0 -1 -2 -3 -4 -5 -6 -7 -8 -8 -9 -10 -11 -12 -13

T 3 3 1 0 -1 -2 -3 -4 -5 -6 -6 -7 -8 -9 -10 -11 -114 4 2 1 0 -1 -2 -3 -3 -4 -5 -6 -7 -8 -9 -9 -10

U 5 5 3 2 1 0 -1 -1 -2 -3 -4 -5 -6 -7 -7 -8 -96 6 4 3 2 1 1 0 -1 -2 -3 -4 -5 -5 -6 -7 -8

R 7 7 5 4 3 3 2 1 0 -1 -2 -3 -3 -4 -5 -6 -68 8 6 5 5 4 3 2 1 0 -1 -1 -2 -3 -4 -4 -5

E 9 9 7 6 6 5 4 3 2 1 0 0 -1 -2 -2 -3 -410 10 8 7 7 6 5 4 3 2 2 1 0 -1 -1 -2 -211 11 9 9 8 7 6 5 4 4 3 2 1 1 0 -1 -112 12 10 10 9 8 7 6 5 5 4 3 3 2 1 1 0

°C 13 13 11 11 10 9 8 7 6 6 5 4 4 3 2 2 114 14 12 12 11 10 9 8 8 7 6 6 5 4 4 3 315 15 13 13 12 11 10 9 9 8 7 7 6 5 5 4 416 16 14 14 13 12 11 11 10 9 8 8 7 7 6 6 517 17 15 15 14 13 12 12 11 10 10 9 8 8 7 7 618 18 16 16 15 14 13 13 12 11 11 10 10 9 9 8 819 19 17 17 16 15 14 14 13 13 12 11 11 10 10 9 920 20 18 18 17 16 16 15 14 14 13 13 12 11 11 11 1021 21 19 19 18 17 17 16 15 15 14 14 13 13 12 12 1122 22 20 20 19 18 18 17 16 16 15 15 14 14 13 13 1323 23 21 21 20 19 19 18 18 17 17 16 16 15 15 14 1424 24 22 22 21 20 20 19 19 18 18 17 17 16 16 15 1525 25 23 23 22 21 21 20 20 19 19 18 18 17 17 17 1626 26 24 24 23 23 22 21 21 20 20 20 19 19 18 18 1827 27 25 25 24 24 23 23 22 22 21 21 20 20 20 19 1928 28 26 26 25 25 24 24 23 23 22 22 21 21 21 20 2029 29 27 27 26 26 25 25 24 24 23 23 23 22 22 22 2130 30 28 28 27 27 26 26 25 25 25 24 24 23 23 23 23

THERMAL

ZONE

SPRING & AUTUMN

THERMAL

COMFORT

COMFORT

ZONE

SUMMER

PHYSICAL

DISCOMFORT

PHYSICAL

DISCOMFORT

FULL SUN

B

C

C

B

A

A

B

CTHERMAL

COMFORT

ZONE

WINTERA



TABLE 18: APPARENT TEMPERATURE (AT) GRID FOR FULL SHADE OUTDOORS

Wind Speed (Top - km/h, Bottom - m/s)

0 4 7 11 14 18 22 25 29 32 36 40 43 47 50 54 km/h0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 m/s

-20 -20 -22 -23 -24 -26 -27 -29 -30 -31 -33 -34 -35 -37 -38 -39 -40-19 -19 -21 -22 -23 -25 -26 -28 -29 -30 -32 -33 -34 -35 -37 -38 -39-18 -18 -20 -21 -22 -24 -25 -27 -28 -29 -30 -32 -33 -34 -35 -37 -38-17 -17 -19 -20 -21 -23 -24 -25 -27 -28 -29 -31 -32 -33 -34 -35 -36-16 -16 -18 -19 -20 -22 -23 -24 -26 -27 -28 -29 -31 -32 -33 -34 -35-15 -15 -17 -18 -19 -21 -22 -23 -25 -26 -27 -28 -29 -31 -32 -33 -34-14 -14 -16 -17 -18 -20 -21 -22 -23 -25 -26 -27 -28 -29 -31 -32 -33-13 -13 -15 -16 -17 -19 -20 -21 -22 -24 -25 -26 -27 -28 -29 -30 -31-12 -12 -14 -15 -16 -18 -19 -20 -21 -22 -24 -25 -26 -27 -28 -29 -30

T -11 -11 -13 -14 -15 -16 -18 -19 -20 -21 -22 -24 -25 -26 -27 -28 -29-10 -10 -12 -13 -14 -15 -17 -18 -19 -20 -21 -22 -24 -25 -26 -27 -28

E -9 -9 -11 -12 -13 -14 -16 -17 -18 -19 -20 -21 -22 -23 -24 -25 -26-8 -8 -10 -11 -12 -13 -14 -16 -17 -18 -19 -20 -21 -22 -23 -24 -25

M -7 -7 -9 -10 -11 -12 -13 -15 -16 -17 -18 -19 -20 -21 -22 -23 -24-6 -6 -8 -9 -10 -11 -12 -13 -15 -16 -17 -18 -19 -20 -21 -22 -23

P -5 -5 -7 -8 -9 -10 -11 -12 -13 -15 -16 -17 -18 -19 -20 -20 -21-4 -4 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16 -17 -18 -19 -20

E -3 -3 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16 -17 -18 -19-2 -2 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16 -17 -18

R -1 -1 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -15 -160 0 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -13 -14 -15

A 1 1 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -11 -12 -13 -142 2 0 -1 -2 -3 -4 -5 -6 -7 -8 -8 -9 -10 -11 -12 -13

T 3 3 1 0 -1 -2 -3 -4 -5 -6 -6 -7 -8 -9 -10 -11 -114 4 2 1 0 -1 -2 -3 -3 -4 -5 -6 -7 -8 -9 -9 -10

U 5 5 4 3 2 1 0 -1 -2 -3 -4 -5 -5 -6 -7 -8 -86 6 5 4 3 2 1 0 -1 -2 -3 -3 -4 -5 -6 -7 -7

R 7 7 6 5 4 3 2 1 0 -1 -2 -2 -3 -4 -5 -5 -68 8 7 6 5 4 3 2 1 0 0 -1 -2 -3 -3 -4 -5

E 9 9 8 7 6 5 4 3 2 2 1 0 -1 -1 -2 -3 -310 10 9 8 7 6 5 4 3 3 2 1 0 0 -1 -2 -211 11 10 9 8 7 6 5 5 4 3 2 2 1 0 0 -112 12 11 10 9 8 7 6 6 5 4 4 3 2 2 1 0

°C 13 13 12 11 10 9 8 8 7 6 5 5 4 3 3 2 214 14 13 12 11 10 9 9 8 7 6 6 5 5 4 3 315 15 14 13 12 11 10 10 9 8 8 7 6 6 5 5 416 16 15 14 13 12 12 11 10 9 9 8 8 7 6 6 517 17 16 15 14 13 13 12 11 11 10 9 9 8 8 7 718 18 17 16 15 14 14 13 12 12 11 10 10 9 9 8 819 19 18 17 16 15 15 14 13 13 12 12 11 11 10 10 920 20 19 18 17 17 16 15 15 14 13 13 12 12 11 11 1121 21 20 19 18 18 17 16 16 15 15 14 14 13 13 12 1222 22 21 20 20 19 18 18 17 16 16 15 15 14 14 14 1323 23 22 21 21 20 19 19 18 18 17 17 16 16 15 15 1424 24 23 22 22 21 20 20 19 19 18 18 17 17 16 16 1625 25 24 23 23 22 21 21 20 20 19 19 18 18 18 17 1726 26 25 24 24 23 22 22 21 21 20 20 20 19 19 18 1827 27 26 25 25 24 24 23 23 22 22 21 21 20 20 20 1928 28 27 26 26 25 25 24 24 23 23 22 22 22 21 21 2129 29 28 27 27 26 26 25 25 24 24 24 23 23 22 22 2230 30 29 28 28 27 27 26 26 25 25 25 24 24 24 23 23

FULL SHADE PHYSICAL

DISCOMFORT

PHYSICAL

DISCOMFORT

THERMAL

ZONE

SPRING & AUTUMN

COMFORT

THERMAL

COMFORT

ZONE SUMMERA

B

C

A

B

C

THERMAL

COMFORT

ZONE

WINTERA

B

C



5.3.1 Thermal Comfort by Zones

The outcome of the sun‐shadow study (see Appendix C) indicates that the development will generally

be in shade at grade level for a large proportion of the time. This applies to the plaza at the east end,

the patio at the southwest corner, and the plaza and main entrances at the southeast corner, among

others. The terrace at Level 11 will be exposed to more sunlight due to greater extension above

surrounding buildings. The terrace at Level 18, as well as the terrace atop the roof deck, will see more

sunlight and more wind. In some specific terms, we find the following conditions based on sun‐shadow

analysis performed for the four days of the year noted in section 4.5.1 (i.e., summer and winter solstice,

spring and autumn equinox). All times are local PDT.

The Sidewalk along Melville Street, the Restaurant Patio, and the Main Building Access Facing the

Plaza (Sensors 37‐42, & 45)

This area will be in shade for the majority of the time throughout the year. The percentage of time

conditions are comfortable for standing or sitting are illustrated in Table 19. These results indicate

conditions are acceptable for the intended uses.

TABLE 19: PERCENTAGE OF TIME OUTDOOR THERMAL COMFORT IS SUITABLE FOR PEDESTRIAN ACTIVITIES BY SEASON

‐ SIDEWALK ALONG MELVILLE STREET, RESTAURANT PATIO, & SOUTH PLAZA ‐

SENSOR # SPRING SUMMER AUTUMN WINTER

37 96% 89% 89% 85%

38 96% 89% 87% 82%

39 95% 89% 87% 82%

40 97% 90% 89% 85%

41 98% 91% 92% 90%

42 99% 92% 94% 92%

45 98% 91% 93% 89%



The Landscaped Pathway and the East Plaza, Inclusive of the Main Entrance (Sensors 27‐31 & 46)

The landscaped pathway along the east side of the building, including the east plaza and main building

entrance, will experience a mix of sun and shadow with increasing sunlight during the summer season.

Smaller sections of the pathway, in particular, also receive intermittent sunlight during short durations

of the afternoon when the sun’s rays pass through gaps in tall buildings facing West Georgia Street,

which is situated to the south of the study site. The percentage of time conditions are suitable for

standing, or better, are illustrated in Table 20. These outcomes assist with creating a comfortable

environment over the noted areas.


‐ LANDSCAPED PATHWAY ALONG EAST SIDE OF BUILDING & EAST PLAZA ‐

SENSOR # SPRING SUMMER AUTUMN WINTER

27 98% 92% 92% 89%

28 98% 92% 94% 91%

29 98% 92% 93% 90%

30 97% 91% 91% 88%

31 98% 92% 93% 90%

46 97% 90% 88% 85%

Laneway along North Elevation, Inclusive of Building Access Points (Sensors 17‐23)

This area will experience mostly shade during the three colder seasons with increasing sunlight during

the summer months. The percentage of time conditions are suitable for standing, or better, are

illustrated in Table 22. These results contribute to creating comfortable conditions over the noted areas.

TABLE 22: PERCENTAGE OF TIME OUTDOOR THERMAL COMFORT IS SUITABLE FOR PEDESTRIAN ACTIVITIES BY SEASON ‐ NORTH LANEWAY + BUILDING ACCESS POINTS ‐

SENSOR SPRING SUMMER AUTUMN WINTER

16 97% 90% 90% 86%

17 98% 91% 92% 89%

18 98% 92% 93% 90%

19 99% 92% 94% 91%

20 98% 91% 94% 91%

21 98% 92% 93% 90%

22 98% 91% 93% 91%

23 98% 92% 93% 91%



Terrace on Level 11 (Sensors 47‐49)

This area experiences shade with intermittent sunlight during the afternoon for three warmer seasons

and full shade during the winter. The percentage of time conditions are suitable for sitting are illustrated

in Table 23. Nonetheless, these results contribute to comfortable conditions suitable for the intended

use of the space throughout the year.


‐ LEVEL 11 TERRACE ‐


47 98% 92% 93% 90%

48 97% 90% 92% 89%

49 96% 89% 92% 89%

Terrace on Level 18 (Sensors 50‐54)

This area experiences shade with intermittent sunlight during all seasons. The percentage of time

conditions are suitable for sitting are illustrated in Table 24. Nonetheless, these results contribute to

comfortable conditions suitable for standing and sitting throughout the year.


‐ LEVEL 18 TERRACE ‐


50 88% 78% 77% 70%

51 95% 88% 89% 85%

52 95% 87% 88% 84%

53 98% 93% 94% 91%

54 95% 87% 88% 84%



Terrace on Roof Deck (Sensors 55‐60)

This is the highest terrace and therefore receives sees the greatest variation of sunlight and shadow.

The percentage of time conditions are suitable for standing and sitting are illustrated in Table 25.

Nonetheless, these results contribute to comfortable conditions suitable for the intended use of the

space throughout the year.


‐ AMENITY AREA ON ROOF DECK ‐


55 96% 86% 89% 85%

56 93% 83% 85% 79%

57 93% 83% 85% 79%

58 92% 79% 85% 78%

59 94% 83% 88% 82%

60 98% 93% 94% 92%



6. SUMMARY AND RECOMMENDATIONS

This report summarizes the results of a pedestrian level wind study and thermal comfort analysis

undertaken for a proposed mixed‐use office building located at 1133 Melville Street in Vancouver, British

Columbia. This work was performed in accordance with the terms and scope of work described in GWE

proposal #17‐074P, dated April 3, 2017, as well as industry‐standard wind tunnel testing and data

analysis procedures.

A complete summary of the predicted wind conditions based on mechanical effects is provided in

Sections 5.1 and 5.2 of this report, and illustrated in Figures 2A‐5B (following the main text). Thermal

effects of wind cooling and solar heating are presented in Section 5.3.

Based on wind tunnel test results, meteorological data analysis of the Vancouver wind climate, and

experience with similar developments in Vancouver, the results of the analyses indicate the following:

1. Wind conditions at grade are found to be calm and suitable for the intended uses over the entire

site without the need for mitigation. The thermal influences serve to extend periods of

pedestrian comfort.

2. Conditions within the large terrace on Level 11 mimic those at grade with comfortable

conditions existing for large proportions of the time, including consideration of thermal effects.

3. Conditions on the remaining large terraces at Levels 16, 18, 26, and the roof deck become

somewhat windier at these levels due to their exposure to stronger winds. However, wind

comfort is increased because of exposure to more sunlight. Nonetheless, the terrace on Level

18, as well as the east terrace on Level 26, would benefit from the introduction of perimeter

wind barriers with a height of 1.8 m above the walking surface to ensure conditions will be

suitable for sitting during the typical use period, if desired.

4. In global terms, pedestrian comfort conditions are found to be acceptable over the entire site

based on the mechanical effects of wind, which are improved when thermal effects are added

into the analysis.

5. However, the wind conditions over the site are sufficiently breezy so that when combined with

the effects of sun and shadow conditions remain comfortable for prolonged exposure.



This concludes our pedestrian level wind and thermal comfort report. Please advise the undersigned of

any questions or comments.

Sincerely,

Gradient Wind Engineering Inc.

Justin Ferraro Vincent Ferraro, M.Eng., P.Eng. Partner Managing Principal



PHOTOGRAPH 1: VIEW OF PLW MODEL LOOKING DOWNWIND

PHOTOGRAPH 2: VIEW OF PLW MODEL LOOKING UPWIND



PHOTOGRAPH 3: CLOSE‐UP VIEW OF PLW MODEL, SOUTHEAST PERSPECTIVE

PHOTOGRAPH 4: CLOSE‐UP VIEW OF PLW MODEL, NORTHWEST PERSPECTIVE


1133 Melville Street, Vancouver: Pedestrian Level Wind Study + Thermal Effects A 1

APPENDIX A

WIND TUNNEL SIMULATION OF THE NATURAL WIND



WIND TUNNEL SIMULATION OF THE NATURAL WIND

Wind flowing over the surface of the earth develops a boundary layer due to the drag produced by

surface features such as vegetation and man‐made structures. Within this boundary layer, the mean

wind speed varies from zero at the surface to the gradient wind speed at the top of the layer. The height

of the top of the boundary layer is referred to as the gradient height, above which the velocity remains

more‐or‐less constant for a given synoptic weather system. The mean wind speed is taken to be the

average value over one hour. Superimposed on the mean wind speed are fluctuating (or turbulent)

components in the longitudinal (i.e. along wind), vertical and lateral directions. Although turbulence

varies according to the roughness of the surface, the turbulence level generally increases from nearly

zero (smooth flow) at gradient height to maximum values near the ground. While for a calm ocean the

maximum could be 20%, the maximum for a very rough surface such as the center of a city could be

100%, or equal to the local mean wind speed. The height of the boundary layer varies in time and over

different terrain roughness within the range of 400 meters (m) to 600 m.

Simulating real wind behavior in a wind tunnel requires simulating the variation of mean wind speed

with height, simulating the turbulence intensity, and matching the typical length scales of turbulence. It

is the ratio between wind tunnel turbulence length scales and turbulence scales in the atmosphere that

determines the geometric scales that models can assume in a wind tunnel. Hence, when a 1:200 scale

model is quoted, this implies that the turbulence scales in the wind tunnel and the atmosphere have the

same ratios. Some flexibility in this requirement has been shown to produce reasonable wind tunnel

predictions compared to full scale. In model scale the mean and turbulence characteristics of the wind

are obtained with the use of spires at one end of the tunnel and roughness elements along the floor of

the tunnel. The fan is located at the model end and wind is pulled over the spires, roughness elements

and model. It has been found that, to a good approximation, the mean wind profile can be represented

by a power law relation, shown below, giving height above ground versus wind speed.

gg Z

ZUU

Where; U = mean wind speed, Ug = gradient wind speed, Z = height above ground, Zg = depth of the

boundary layer (gradient height) and is the power law exponent.



Figure A1 plots three such profiles for the open country, suburban and urban exposures. The exponent

varies according to the type of terrain; = 0.14, 0.25 and 0.33 for open country, suburban and urban

exposures respectively. Figure A2 illustrates the theoretical variation of turbulence in full scale and some

wind tunnel measurement for comparison.

The integral length scale of turbulence can be thought of as an average size of gust in the atmosphere.

Although it varies with height and ground roughness, it has been found to generally be in the range of

100 m to 200 m in the upper half of the boundary layer. For a 1:300 scale, for example, the model value

should be between 1/3 and 2/3 of a meter. Integral length scales are derived from power spectra, which

describe the energy content of wind as a function of frequency. There are several ways of determining

integral length scales of turbulence. One way is by comparison of a measured power spectrum in model

scale to a non‐dimensional theoretical spectrum such as the Davenport spectrum of longitudinal

turbulence. Using the Davenport spectrum, which agrees well with full‐scale spectra, one can estimate

the integral scale by plotting the theoretical spectrum with varying L until it matches as closely as

possible the measured spectrum:

3

4

210

2

210

2

41

4

)(

U

Lf

U

Lf

fSf

Where, f is frequency, S(f) is the spectrum value at frequency f, U10 is the wind speed 10 m above ground

level, and L is the characteristic length of turbulence.

Once the wind simulation is correct, the model, constructed to a suitable scale, is installed at the center

of the working section of the wind tunnel. Different wind directions are represented by rotating the

model to align with the wind tunnel center‐line axis.



REFERENCES

1. Teunissen, H.W., ‘Characteristics Of The Mean Wind And Turbulence In The Planetary Boundary

Layer’, Institute For Aerospace Studies, University Of Toronto, UTIAS # 32, Oct. 1970

2. Flay, R.G., Stevenson, D.C., ‘Integral Length Scales In An Atmospheric Boundary Layer Near The

Ground’, 9th Australian Fluid Mechanics Conference, Auckland, Dec. 1966

3. ESDU, ‘Characteristics of Atmospheric Turbulence Near the Ground’, 74030

4. Bradley, E.F., Coppin, P.A., Katen, P.C., ‘Turbulent Wind Structure Above Very Rugged Terrain’, 9th

Australian Fluid Mechanics Conference, Auckland, Dec. 1966



Figure A1 (Top): Mean Wind Speed Profiles

Figure A2 (Bottom): Turbulence Intensity Profiles (u’ = fluctuation of mean velocity)

0

0.2

0.4

0.6

0.8

1

0.00 0.20 0.40 0.60 0.80 1.00

U/Ug

Z/Z

g

urban

s uburban

open

A) Normalized Wind Speed Profiles

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.000 0.100 0.200 0.300 0.400 0.500 0.600

u'/U

Z/Z

g

urban

s uburban

open

B) T urbulence Intensity Profiles

A1) Normalized Wind Speed Profiles

A2) Turbulence Intensity Profiles


1133 Melville Street, Vancouver: Pedestrian Level Wind Study + Thermal Effects B 1

APPENDIX B

PEDESTRIAN LEVEL WIND MEASUREMENT METHODOLOGY



PEDESTRIAN LEVEL WIND MEASUREMENT METHODOLOGY

Pedestrian level wind studies are performed in a wind tunnel on a physical model of the study buildings

at a suitable scale. Instantaneous wind speed measurements are recorded at a model height

corresponding to 1.5 metres (m) full scale using either a hot wire anemometer or a pressure‐based

transducer. Measurements are performed at any number of locations on the model and usually for 36

wind directions. For each wind direction, the roughness of the upwind terrain is matched in the wind

tunnel to generate the correct mean and turbulent wind profiles approaching the model.

The hot wire anemometer is an instrument consisting of a thin metallic wire conducting an electric

current. It is an omni‐directional device equally sensitive to wind approaching from any direction in the

horizontal plane. By compensating for the cooling effect of wind flowing over the wire, the associated

electronics produce an analog voltage signal that can be calibrated against velocity of the air stream. For

all measurements, the wire is oriented vertically so as to be sensitive to wind approaching from all

directions in a horizontal plane.

The pressure sensor is a small cylindrical device that measures instantaneous pressure differences over

a small area. The sensor is connected via tubing to a transducer that translates the pressure to a voltage

signal that is recorded by computer. With appropriately designed tubing, the sensor is sensitive to a

suitable range of fluctuating velocities.

For a given wind direction and location on the model, a time history of the wind speed is recorded for a

period of time equal to one hour in full‐scale. The analog signal produced by the hot wire or pressure

sensor is digitized at a rate of 400 samples per second. A sample recording for several seconds is

illustrated in Figure B1. This data is analyzed to extract the mean, root‐mean‐square (rms) and the peak

of the signal. The peak value, or gust wind speed, is formed by averaging a number of peaks obtained

from sub‐intervals of the sampling period. The mean and gust speeds are then normalized by the wind

tunnel gradient wind speed, which is the speed at the top of the model boundary layer, to obtain mean

and gust ratios. At each location, the measurements are repeated for 36 wind directions to produce

normalized polar plots, which will be provided upon request.

In order to determine the duration of various wind speeds at full scale for a given measurement location

the gust ratios are combined with a statistical (mathematical) model of the wind climate for the project

site. This mathematical model is based on hourly wind data obtained from one or more meteorological



stations (usually airports) close to the project location. The probability model used to represent the data

is the Weibull distribution expressed as:

C

U gK

Ag

UP

exp

Where,

P (> Ug) is the probability, fraction of time, that the gradient wind speed Ug is exceeded; is the wind

direction measured clockwise from true north, A, C, K are the Weibull coefficients, (Units: A ‐

dimensionless, C ‐ wind speed units [km/h] for instance, K ‐ dimensionless). A is the fraction of time

wind blows from a 10° sector centered on .

Analysis of the hourly wind data recorded for a length of time, on the order of 10 to 30 years, yields the

A, C and K values. The probability of exceeding a chosen wind speed level, say 20 km/h, at sensor N

is given by the following expression:

g

N

N

U

UPP

2020

PN ( > 20 ) = P { > 20/(UN/Ug) }

Where, UN/Ug is the aforementioned normalized gust velocity ratios where the summation is taken over

all 36 wind directions at 10° intervals.

If there are significant seasonal variations in the weather data, as determined by inspection of the C

and K values, then the analysis is performed separately for two or more times corresponding to the

groupings of seasonal wind data. Wind speed levels of interest for predicting pedestrian comfort are

based on the comfort guidelines chosen to represent various pedestrian activity levels as discussed in

the main text.



FIGURE B1: TIME VERSUS VELOCITY TRACE FOR A TYPICAL WIND SENSOR

REFERENCES

1. Davenport, A.G., ‘The Dependence of Wind Loading on Meteorological Parameters’, Proc. of Int.

Res. Seminar, Wind Effects On Buildings & Structures, NRC, Ottawa, 1967, University of Toronto

Press.

2. Wu, S., Bose, N., ‘An extended power law model for the calibration of hot‐wire/hot‐film constant

temperature probes’, Int. J. of Heat Mass Transfer, Vol.17, No.3, pp.437‐442, Pergamon Press.

0

10

20

30

40

0 100 200 300 400 500

Pre

ssu

re (

Pas

cal)

Time (milli-seconds)


1133 Melville Street, Vancouver: Pedestrian Level Wind Study + Thermal Effects C 1

APPENDIX C

SHADOW RENDERINGS



TABLE C1: SHADOW RENDERING DATES AND TIMES

TIME

(PDT)

March 21st

(Figure / Page #)

June 21st

(Figure / Page #)

September 21st

(Figure / Page #)

December 21st

(Figure / Page #)

9:15 AM C1 / C3 C11 / C8 C21 / C13 C31 / C18

10:15 AM C2 / C3 C12 / C8 C22 / C13 C32 / C18

11:15 AM C3 /C4 C13 / C9 C23 / C14 C33 / C19

12:15 PM C4 / C4 C14 / C9 C24 / C14 C34 / C19

1:15 PM C5 / C5 C15 / C10 C25 / C15 C35 / C20

2:15 PM C6 / C5 C16 / C10 C26 / C15 C36 / C20

3:15 PM C7 / C6 C17 / C11 C27 / C16 C37 / C21

4:15 PM C8 / C6 C18 / C11 C28 / C16 FULL SHADE





FIGURE C1: MARCH 21ST, 9:15 AM





FIGURE C4: MARCH 21ST, 12:15 PM



FIGURE C11: JUNE 21ST, 9:15 AM





FIGURE C14: JUNE 21ST, 12:15 PM



FIGURE C21: SEPTEMBER 21ST, 9:15 AM





FIGURE C24: SEPTEMBER 21ST, 12:15 PM



FIGURE C31: DECEMBER 21ST, 9:15 AM





FIGURE C34: DECEMBER 21ST, 12:15 PM

Pedestrian Level Wind Study - Vancouver

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