Dissertation. Undergrad

Aniket Gohil | K1127347
Kingston University
AN IN-DEPTH
RESEARCH
ABOUT
PROBLEMS
CAUSED AT
BRIDGEWATER
PLACE
Supervisor: Dr. Anna Cheah

I
ABSTRACT
Construction of a building links to major changes of microclimate in the vicinity, particularly
high-rise buildings where great wind speeds are experienced at pedestrian level causing
dangerous hazards and accidents. Therefore, the design of the building has to take outdoor
climate into account at the same level as the indoor climate, comfort, and environment. Wind
environment in outdoor climate has been given little attention by designers and engineers
and with growing demand of the topic, before the construction process, designs are studied
for wind speed at pedestrian level, highlighting building aerodynamics. The present
dissertation focus on pedestrian comfort, where a case study of Bridgewater Place, Leeds is
taken as the subject. Prior to completion of the building in 2007, high wind speed between
67mph – 79 mph (BBC, 2011) were captured by pedestrians. At present, the structure is
involved in 25 serious complaints and in process to provide a viable solution to the problem.
Brief illustrations and comparisons will be commenced on related projects and the use of
traditional wind tunnel machine and CFD (computer fluid dynamics) will also be presented.
KEY WORDS: Microclimate, outdoor climate, pedestrian comfort, building aerodynamics,
wind tunnel, CF.

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CONTENTS
ABSTRACT............................................................................................................................................I
LIST OF FIGURES, TABLES AND APPENDICIES .....................................................................IV
FIGURES..........................................................................................................................................IV
TABLES ............................................................................................................................................V
APPENDICIES .................................................................................................................................V
ACKNOWLEDGEMENT....................................................................................................................VI
1. INTRODUCTION..........................................................................................................................1
1.1. GENERAL.............................................................................................................................1
1.2. OBJECTIVES .......................................................................................................................2
1.3. APPROACH..........................................................................................................................2
1.4. OUTLINE...............................................................................................................................3
2. LITERATURE REVIEW ..............................................................................................................4
2.1. BUILDING STRUCTURES.................................................................................................4
2.1.1. BUILDING’S SHAPE, SIZE, AND ORIENTATION ................................................5
2.1.2. BUILDING AERODYNAMICS ...................................................................................5
2.2. PEDESTRAIN WIND LEVELS ........................................................................................10
2.2.1. DIFFERENT TYPES OF WIND EFFECTS ............................................................11
2.2.2. PEDESTRIAN COMFORT CRITERIA....................................................................14
2.3. WIND COMFORT CRITERIA...........................................................................................18
2.4. METHODOLOGY AND CONCLUSION .........................................................................19
3. METHODOLOGY AND LIMITATIONS...................................................................................21
3.1. CURRENT PROBLEMS ...................................................................................................21
3.1.1. SHAPE.........................................................................................................................21
3.1.2. LOCATION..................................................................................................................24
3.1.3. ORIENTATION...........................................................................................................25
3.2. USE OF CFD SOFTWARES............................................................................................25

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3.2.1. ADOBE PROJECT VASARI ....................................................................................25
4. RESULTS....................................................................................................................................28
4.1. SOLUTION 1.......................................................................................................................28
4.2. SOLUTION 2.......................................................................................................................30
5. ANALYSIS ..................................................................................................................................32
5.1. USE OF MATERIALS .......................................................................................................32
5.1.1. SOLUTION 1...............................................................................................................32
5.1.2. SOLUTION 2...............................................................................................................33
5.2. AESTHETICS .....................................................................................................................33
5.2.1. SOLUTION 1...............................................................................................................33
5.2.2. SOLUTION 2...............................................................................................................34
5.3. COMPARISON TO CURRENT SITUATIONS...............................................................34
5.3.1. SOLUTION 1...............................................................................................................34
5.3.2. SOLUTION 2...............................................................................................................34
5.4. PREFOUND SOLUTION ..................................................................................................34
5.4.1. PROPOSED SOLUTION AND PLANS..................................................................35
6. DISCUSSION..............................................................................................................................37
6.1. HYPOTHESIS AND CURRENT STUDY........................................................................37
6.2. COMPARISON BETWEEN FOUND SOLUTION AND CPPI SOLUTION ...............38
7. CONCLUSION............................................................................................................................39
8. REFERENCES ...........................................................................................................................40
9. APPENDIX 1: SUPERVISOR SIGN OFF SHEET................................................................43

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LIST OF FIGURES, TABLES AND APPENDICIES
FIGURES
Figure 1: Wind flow around a high-rise building (Blocken & Carmeliet, 2004)........................ 6
Figure 2: Short-circuiting pressure caused by passage through building (Blocken &
Carmeliet, 2004) ................................................................................................................... 8
Figure 3: Effects of short-circuiting pressure on building with a passage. (Vardoulakis, et al.,
2001)..................................................................................................................................... 8
Figure 4: Four case scenarios of passage between buildings. (Vardoulakis, et al., 2001)...... 9
Figure 5: Lawson comfort criteria (Waterman Group, 2012) ................................................ 13
Figure 6: Wind speed in a Middle Eastern city. (a) Annual speed, (b) daily variation of wind
speed. (Ghosh & Mittal , 2012)............................................................................................ 15
Figure 7: Scour technique wind tunnel diagram (Blocken & Carmeliet, 2004)...................... 16
Figure 8: Smoke aided wind tunnel technique (Blocken & Carmeliet, 2004) ........................ 17
Figure 9: Section one of Bridgewater Place (Gohil, 2014) ................................................... 21
Figure 10: Downwash wind after being reflected from building surface (Gohil, 2014) .......... 22
Figure 11: Section two of Bridgewater Place (Gohil, 2014).................................................. 22
Figure 12: Section three of Bridgewater Place (Gohil, 2014) .............................................. 22
Figure 13: 2D and 3D viewpoint of Bridgewater Place (diagram not in scale) (Gohil, 2014) 23
Figure 14: Wind direction viewpoint (UK) (Met Office, 2014) .............................................. 24
Figure 15: Wind direction viewpoint (Leeds) (Met Office, 2014).......................................... 24
Figure 16: Bridgewater Place orientation against wind direction. (Google Maps, 2014)....... 25
Figure 17: Original orientation of Bridgewater Place against wind. (Gohil, 2014)................. 26
Figure 18: 90° orientation of the building (Gohil, 2014)........................................................ 26
Figure 19: 270° orientation of the building. (Gohil, 2014)..................................................... 26
Figure 20: Wind reaction when hit building surface (Gohil, 2014) ........................................ 27
Figure 21: Solution 1 (Gohil, 2014)...................................................................................... 28
Figure 22: Solution one: (a) top view (b) western view (c) zoomed in view of the solution
(Gohil, 2014) ....................................................................................................................... 29
Figure 23: Solution 2 (Gohil, 2014)...................................................................................... 30
Figure 24: Solution two: (a) top view (b) western view (c) zoomed in view of the solution
(Gohil, 2014) ....................................................................................................................... 31
Figure 25: Wind travel around a structure after installation of canopy (Gohil, 2014) ............ 33
Figure 26: Bridgewater Place wind reduction proposal (Bridgewater Place, 2014) .............. 35

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Figure 27: 3d view of Bridgewater Place wind reduction scheme (Bridgewater Place, 2014)
........................................................................................................................................... 36
Figure 28: Proposed solution: (a) top view (b) western view (c) zoomed in view of the
solution (Gohil, 2014) .........................................................................................................36
TABLES
Table 1: Wind effects on people based on beaufort scale (Baniotopoulos, et al., 2011) ...... 12
Table 2: Definition of pedestrian activity categories (PAC) (Koss, 2006) ............................. 19
APPENDICIES
Appendix 1: Supervisor sign off sheet….…………………………………………………………42

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ACKNOWLEDGEMENT
I would never have been able to finish my dissertation without the guidance of my friends,
family and my supervisor.
I would like to express my sincere gratitude to my supervisor, Dr. Anna Cheah without whom
I would not have been able to choose this project. With her excellent thorough knowledge
and understanding on my topic along with great guiding, I have been successful to complete
this project without any issues.

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1. INTRODUCTION
1.1.GENERAL
The awareness of high wind speeds caused by buildings has been raised through many
years. The construction of many high-rise structures have created dangerous environments
for pedestrians and other road users. This shows the lack in study of outdoor climate effect
in relation to building by both engineers and architects.
It has been showcased in most cases that the main area of concern is the location,
orientation and the shape of the structure. In Roman times, during these issues Vitruvius (a
Roman architect, engineer and an author) had recommended the orientation of streets
diagonally to prevailing winter winds (Aynsley, 1989).
With modernisation of construction materials and construction methods, taller buildings are
constructed in both cities and towns. Among the effects of high wind speeds created in the
vicinity of the buildings, the most significant ones is the pedestrian comfort and safety. Note
that a death of a man had been reported when a lorry toppled over him due to high wind
speeds (BBC, 2011), a woman was severely injured when a gust of wind blew her away
(BBC, 2013).
With growing awareness of high wind speeds at pedestrian level, measures and tests have
been progressed around the world in the last 30 years. Growing amount of cities and
governments are planning to pass a bylaws and acceptance criteria on the amount of wind
conditions at pedestrian level. A permit on satisfactory wind environment is required in order
to build a new structure in cities such as London, Tokyo, San Francisco, Calgary and
Montreal (American Society of Civil Engineers, 1989).
Wind environment and pedestrian wind speeds are usually influenced by building geometry,
building vicinity and local metrological data. It is essential for designers and engineers to
consider wind environment at preliminary stage where alteration are acceptable.
Unfortunately, there is yet not a general theory to determine wind environment or a theory to
develop a solution to upcoming unacceptable wind conditions. Any errors that arise can only
be checked on wind tunnel or on CFD (Computer Fluid Dynamics) at preliminary stages.
Therefore, it is essential to obtain a systematic approach on designing for being able to
make changes to the designs if necessary.

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1.2.OBJECTIVES
The literature knowledge on wind tunnel effects and its effects at pedestrian levels had
thoroughly been reviewed during the first stage on progression of the current project. A
general feedback received from the literature review was the lack of knowledge on minor
aspects of wind environment and unclear explanation of complex materials in many
circumstances.
The main aim of this project is a complete understanding of wind aerodynamics, wind
environment at pedestrian levels and around building vicinity and to also find a viable
solution to set case study. Elements that react to different wind behaviour are to be
thoroughly checked via CFD method in terms to find the most suitable solution to the known
problem. The general objectives of the project are as follows:
(1) Re-evaluation of literature review to present clear understandings of complex
subjects;
(2) Obtain and express great knowledge of unknown subjects;
(3) Using the CFD tools to understand the aerodynamics to produced solutions; and
(4) A detailed explanation of material usage in final solutions.
1.3.APPROACH
In order to achieve set goals and objectives, a unique approach has been adopted in the
current study.
Although most of previous case studies and research were conducted on a traditional wind
tunnel to record wind interaction with the structure, CFD method is to be conducted to test
and work out the solutions. In this way the time spent on the construction of the model is
obliterated. The offset approach forms a strong foundation for an advanced knowledge.
Wind tunnel testing is widely used in understanding of wind environments, wind flow around
building and pedestrian wind level. Integration of methods within this testing can provide high
quality results; such as surface pressure, flow visualisation and thermal anemometers.
Further insight into the problems can be obtained by more fundamental studies. Construction
of appropriate models has been done to gain a well-established knowledge onto main area
of problems from which isolated sections are constructed as a benchmark model.

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Instead of using the traditional method, the designs can be integrated on CAD software to
understand the wind flow allowing easier and quicker modification. The use of knowledge
achieved from literature review is applied on the CAD model to obtain in-depth accurate
results.
1.4.OUTLINE
The dissertation consists of seven chapters, a list of references and appendices.
The literature review on pedestrian wind levels is presented in Chapter 2 with wind
environment and aerodynamics. Detailed information on methods to test wind environment
at pedestrian level are also presented along with use of diagrams and tables for clear
understanding. Identification of current problem at Bridgewater Place is explained in-detail in
Chapter 3 with the possibility in use of CFD experimental technique.
Chapter 4 presents the final two solutions to Bridgewater Place with aid from imagery and
the CFD software used. In-depth solution with complex data, comparisons of before and
after building solutions will be shown in Chapter 5 along with building affect to the
surrounding area after solutions along with isolated sections viewpoints.
Based on literature information obtained, the found solutions achieved from previous chapter
are referred back to Chapter 2 in Chapter 6. The system is described with its general
architecture, components and application examples in this chapter.
As a conclusion of this project, Chapter 7 summarises the contribution of this project to both
building applications and wind aerodynamics. Future elements are also considered where,
recommendations are provided for any similar upcoming problems to other structures such
as the many ways to experiment wind environment, modelling of the structure, and the
potential areas of concerns with improvements.
References are provided in Chapter 8 and useful documents are presented in Chapter 9 as
“Appendices”.

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2. LITERATURE REVIEW
Before the design and construction phase of a structure, the structure plays a major role
dealing with both indoor and outdoor climates. Indoor climate deals with user comfort;
outdoor climate in other hand is given relatively less attention where pedestrian comfort is an
issue to investigate. The construction of a building inevitably changes the microclimate at the
site, e.g. wind speed, air pollution, light reflection, and wind direction (Blocken & Carmeliet,
2004). It also depends on its shape, size, and orientation, causing unfavourable changes
around the site, such as: high wind speeds causing dangerous conditions for pedestrians
and road users; low wind speeds causing insufficient removal of pollution caused; sunlight
reflection off the building; and visual pollution (blocking the view). Wind speed at pedestrian
level can be calculated and compared to previous records, if exceeding set frequencies,
models are tested on wind tunnel or CFD to produce long term viable solutions.
Climate is another key aspect in variation of microclimate of an area, e.g. moderate climate
conditions during cold days with reduced wind speeds can create discomfort at pedestrian
level. Wind speed could create rain infiltration (Blocken & Carmeliet, 2004b) and snow
accretion (Beyers & Waechter, 2008) causing local floods and levels of snow on road. Both
methods CFD and wind tunnel testing were conducted by Blocken, et al., (2012) and Tsang,
et al., (2012) respectively to assess pedesterian wind level and wind comfort in urban
regions.
With raising demand and interest on the matter from past incidents including deaths and
other serious injuries caused to road users (trajic death of a man after a lorry being toplled
over him due to high wind speeds), authors, architectures, and engineers such as:
Stathopoulos, (2006); Moonen, et al., (2012); Blocken & Carmeliet, (2008), etc. have been
publishing journals and articles in order to raise awarness and provide solutions to present
occuring incidents.
2.1. BUILDING STRUCTURES
Building’s body and aerodynamics play a critical role in effect to wind response. Tall
buildings can be susceptible to excessive motion during wind events leading to pedestrian
and occupant discomfort, reducing the overall impact and appeal of the structure (Merrick &
Bitsuamlak, 2009).

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With aid of methods such as CFD and wind tunnel, solutions can be found in preliminary
stage of design finalisation on wind response to building structures.
2.1.1. BUILDING’S SHAPE, SIZE, AND ORIENTATION
With modern studies and technology, unique shapes and sizes have been introduced to
building structurs and the possibilites of these designs working with due respect to wind
speed and load are growing day by day. However, some designs may not refer to wind in the
area of construction, causing wind tunnel effect.
A structure submerged in given flow field is subjected to aerodynamics flows and forces.
Typically, there are three different forms of forces involved around tall building structures
(Amin & Ahuja, 2010):
> Drag froces (along – wind): Along wind forces act in the direction of mean flow
(horizontal). This force includes structure’s response to pressure fluctuation on windward
and leeward faces with response to building. Use of wind tunnel or CFD helps a user in
understanding wind flow along a building and note the events occuring.
> Lift forces (across – wind): Across wind forces act perpendicular to direction of
mean flow (vertical). Tall buildings highlights on division of wind flow from the surface of the
building, following structure’s body contours.
Across wind achieved from division in addition to along wind, when meeting ground level
creates vortex around the structure resulting in human discomfort.
> Torsional motion: Torsional motion is established when there is a vast difference
between elastic centre and aerodynamics center of a structure. This results in vibration of
the structure leading to failure (structure collapses).
2.1.2. BUILDING AERODYNAMICS
Wind flow around a building is crucial to understand human comfort. In this sections two
case scenerios will be accounted to assess a full scale wind flow around a single high rise
and wind flow around multiple high rise buildings with aid of CFD and wind tunnel:

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> Wind flow around a single high rise building:
Shown below in figure 1 is a schematic representation of wind flow around a single high rise
building:
Figure 1: Wind flow around a high-rise building (Blocken & Carmeliet,2004)
As wind approaches the building it diverges: (1) some of the wind flows over the building (2)
high amount of wind is then flown towards stagnation point which is located at approximately
70% of the building height. From this point, wind flow is divided into three sections where it
flows over the building (3), flows sideways (4), and downwards (5). Wind flown downwards
from stagnation point, creates vortex when hit ground level (6). There are three different
types of vortexes that could occur: standing vortex, frontal vortex, and horseshoe vortex. The
main position of standing vortex near ground level is opposite to the flow mean wind
direction. When both of these flow meet, a stagnation point at ground level with low wind
speeds is created (7). The standing vortex created at point 6 is then stretched outwards to
be passed from corners of the building where seperation occurs and corner streams with
high wind speeds are achieved (8). The corner streams then merge with the general wind
flow from point 2 (9). At leeward side of the building, the general flow is turned into backflow
and recirculation flow (10, 13). This is where an underpressure zone is created. At the end of
backflow and recirculation flow, another stagnation point is created at ground level of the
building where low wind speeds exist (11). At the end of stagnation zone, the wind is flown

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with the general mean flow at low speed for a considerable distance (12). The backflow in
the leeward side of the building creates slow vorticies (13). With the mixture of these slow
vorticies at point 13 and corner streams at point 9, a high velocity gradient zone is generated
which comprises of small fast rotating vorticies (16).
From the discussed diagram there are two pressure systems discovered. The first pressure
occurs on the front façade of the building, where high wind speeed pressure are experienced
at the stagnation point and lower wind speed pressure at the rest of the façade. This
pressure system is generated by the approaching of wind force with respect to height
creating standing vortex that slip off through the corners of the building, called “corner
streams”. The second pressure system is created between windward side and leeward side
of the building where overpressure and underpressure meet causing recirculation
downstream of the building and also contributing to the flow at corner strems. Both of these
pressure systems illustrate the complexity in wind flow pattern in response to a structure.
> Wind flow around different building arrangements
In this section, wind flow around two different building arrangements are discussed:
(1) Passage through a building
Passages through building are designed to improve accessibility for cars, pedestrians, and
cyclists. These passages provide easier access to the front and the back façade of the
building. Figure 2 shows a diagram of short-circuiting pressure caused by passage through
building. With an example, building with a dimension of 160m x 10m x 25m and passage
dimension of 10m x 10m is used to test wind interface around the structure. As seen from
the diagram, short-circuiting pressure is created between the leeward and windward façade
of the building creating unfavourable wind condition in the passage.

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Figure 2: Short-circuiting pressure caused by passage through building (Blocken & Carmeliet, 2004)
Figure 3: Effects of short-circuiting pressure on building with a passage. (Vardoulakis, et al.,2001)
Short-circuiting pressure
Wind
Under-pressure zone
Over-pressure zone

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Shown in Figure 3 are the effects of short-circuiting pressure caused due to passage through
a building. Due to these conditions, standing vortex on front façade doesn’t make much
effect. However, through passage and corner streams experience high wind levels of up to
1.8 m/s. The easiest ways to avoid the high wind speeds would be to introduce the use of
screens through the passage to increase flow resistence.
(2) Parallel buildings with passage in between
As opposed to through passages in building, passages between buildings are pervasive.
The effects of these passages between two high rise buildings are reported uncomfortable
for pedestrians. Wind tunnel studies undertaken on the subject have provided remarkable
results. Figure 4 shows four different case scenerios, each with decreasing passage
between two buildings:
Figure 4: Four case scenarios of passage between buildings. (Vardoulakis, et al., 2001)

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Two buildings shown in figure 4a with a width of 80m displays that there is slight interaction
between two building and wind flows as it would with around an isolated building. Both
buildings have their own stagnation points, corner streams, and standing vortecies. As the
width is decreased (figure 4: b, c, and d) the wind interaction between building passages
increases, standing vortecies, opposite corner streams, and stagnation point start merging
creating one large zone. However, the intriguing factor seen is that as the opposite corner
streams are moved closer, the amplifications between the building decreases (especially
behind the buildings). According to pedestrians, higher wind speeds are experienced as the
passage width decreased. In order to work out the solution to the matter, writer Blocker, B.
and Carmeliet, J. inform that pedestrians walking through the passage shown will tend to
avoid corners, experiencing lower wind speeds. As the passage width is decreased, the
corner streams will merge meaning high wind speed region created between these buildings
cannot be avoided leaving unfavourable experience for pedestrians.
2.2. PEDESTRAIN WIND LEVELS
Wind speed at ground levels is one of many important factors in construction of a building. It
is vitial to acknowledge the speed of the wind at ground levels in order to understand its
effect to human comfort. The use of CFD and wind tunnel aid on this. The complexity of wind
generally relies on the aerodynamics of the building to gain knowledge on how it streams
around a structure. In order to design a solution to obtain pedestrian level wind speed, CFD
and wind tunnel tests are directed to achieve practical results according to which building
design can be changed to fit the criteria. These processes raise awarness in areas that need
improvement in comfort and safety for pedestrians.
Human comfort level varies according to the shape, size, height, and orientation of the
building. As known, wind is normally deflected around or downwards to the ground when hit
building surface. The speed however varies according to the height, called “wind speed
gradient”. In relation to the height of the building, the speed of the wind vaires; the taller the
structure, the higher the wind speed. Although, speed is recognised most, it is also
significant to consider other factors such as, wind direction; height of the building; location of
the building; and turbulance effects.
Influence of wind speed on building’s vicinity and its effects is crucial to predict the overall
effect on the environment. It is vital to know the response of gust speed in an area, e.g.
during gust effects: the speed of the wind that will be experienced, the direction, and the

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variation in direction of wind. As wind speeds are low on ground level with high shear stress,
sudden change in atmosphere with low turbulance frequency can result in hazardous control
and safety. Therefore, a structure has to accomplish these needs with viable, realistic, low
cost, and high accuracy designs which are both safe for the environment and pedestrians.
2.2.1. DIFFERENT TYPES OF WIND EFFECTS
There are a range of wind effects which need to be taken account of when designing and
constructing a building structures. These wind effects convey results on speed at which
safety is changed to hazard. The following are types of wind effects to take count of
pedestrian safety:
> Wind Effects: Wind effects are generally distinguished into two parts: mechanical effects
and thermal effects. Mechanical effects are tests where wind speed can be adjusted from a
breeze to a gust. These tests are taken in order to understand its effects on people. Based
on research led by Penwarden, A.D., (1973) the effect of different wind speeds are shown in
Table 1. This table is divided into different wind speed levels for which its effects are given.
The table is divided into three groups when urban area is taken as the subject:
1. Wind speed less then 5.4 m/s are counted as moderate wind speed with least
effect to human body. The most a pedestrian can feel is gentle breeze. This type of
wind speed is ideal for urban areas.
2. Wind speed between 5.5 m/s – 13.8 m/s are counted as harsh wind speeds with
low damage to pedestrians. The most a pedestrian can feel is strong breeze.
3. Wind speed between 13.9 m/s – 24.4 m/s are counted as hazardous and
dangerous wind speed which causing high damage to pedestrians.

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Wind type Speed
(m/s)
Description of wind effects Description of wind
Moderate wind
speeds
1
Less than
1.5
No noticable wind Light airs
2 1.6 – 3.3 Wind felt on face Light breeze
3 3.4 – 5.4
> Wind extends light flag.
Gentle breeze> Hair is disturbed.
> Clothing flaps.
Harsh wind
speeds
4 5.5 – 7.9
> Wind raises dust, dry soil, and loose
paper. Moderate breeze
> Hair disarranged.
5 8.0 – 10.7
> Force of wind felt on body.
Fresh breeze> Drifting snow becomes airborne.
> Limit of aggreable wind on land.
6
10.8 –
13.8
> Umbrellas used with difficulty.
Strong breeze
> Hair blown striahgt.
> Difficult to walk steadily.
> Wind noises on ears unpleasent.
> Windborne snow above head height
(blizzard)
Dangerous /
hazardous
wind speeds
7
13.9 –
17.1
Inconvenience felt when walking. Moderate gale
8
17.2 –
20.7
> Generally impeds progress.
Fresh gale> Great difficulty with balance in
gusts.
9
20.8 –
24.4
> People blown over by gusts. Strong gale
Table 1: Wind effects on people based on beaufort scale (Baniotopoulos, et al.,2011).
Thermal wind effects are more complex than mechanical. As thermal wind effects deal with
real time wind, more than one parameters involved in this effect, such as: wind speed, wind
direction, temperature, humidity, weather condition, radiation, etc.. These parameters
conclude on a pedestrian’s overall thermal comfort, so in order to keep a pedestrian feel safe
in the environment, number of parameters have to be considered.

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Considered by researchers such as SKF, mechanical effects wind test can be more reliable
and cost effective as changes and predictions can be done in order to modify structure
designs to meet wind speed criteria. However, when compared to thermal effects, a whole
set of environment has to be set up in order to test the situations.
> Wind Comfort: Wind comfort is a comfort criteria where people not only feel comfortable
indoors, but outdoors too. Although, there are a range of comfort criterias for different types
of road users who have diverse perceptions on thermal wind effects, e.g. road users look for
clamer wind speeds when sat in park than what they would expect when walking to work.
However, wind speed is not an important factor in this matter, wind presistence and wind
frequency are considered too. The use of mechanical wind effects can be a good guidance
to work out precise human comfort under certain wind speeds. Figure 5 shows Lawson
comfort criteria for safe wind conditions required for certain types of activities. The given
figure relates to data from Table 1 shown above.
Lawson developed a criteria to assess wind conditions in an urban environment and how
they relate to wind presistence and treshold. It defines comfort level/ tolerable wind speeds
(Beaufort force) for certain types of road users ranging from sitting to leisure walking to
business walking. If given wind speed goes over the set parameters, then it is not suitable
for that certain activity any longer. However, if gone under the set parameters then activity is
considered allowable. For example: wind parameters for sitting are 0 – 3 Beaufort force for
1%, if the wind speed went over 3 Beaufort force then sitting is considered unsafe.
Figure 5: Lawson comfort criteria (Waterman Group, 2012)

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> Wind Climate: Wind affects the climate of an area. Wind unlike other types, wind climate is
not highly based on wind speed. It is however divided into three sections where in order to
achieve wind climate for a certain area, long term statistical metrological data and wind
stastics are collected from metrological stations. This data is then linked to the aerodynamics
of the geometrical site of the building, where wind climate is to be calculated. Once the first
two steps are complete and wind climate for a particular geometrical site is achieved, then a
comfort criteria is produced in order to review local wind climate and take any precausions if
need to.
> Wind Danger: Wind danger is a similar factor to wind speed. It takes account of the speed
of the wind at which an activity gets dangerous. As mentioned in wind comfort about Lawson
comfort criteria and wind speed about ranging wind speeds in relation to description of its
effect.
Falling into group three, number of incidents were caused at Bridgewater Place due to
strong gale. Dangerous and hazardous wind speeds experienced caused a lorry to be
toppled over causing death of a man. Other serious incidents such as torn liver and internal
bleeding were caused due to strong gust experienced.
2.2.2. PEDESTRIAN COMFORT CRITERIA
In order to determine pedestrain wind comfort, this section is divided into three sub-sections:
1. Metrological data of local area, study of wind in different weather conditions.
In order to collect metrological data for a local area, a long term wind data is required. This
data provides the user with information such as range in wind speeds and wind directions.
The data collected are then used to design stastical models.
To obain thermal comfort and other microclimate data, in-detail wind analysis for the
following parameters is required (Wu & Kriksic, 2012):
 Concurrences of winds with other weather events (e.g., snow, rain, fog, sand
storms);
 Joint probability of wind, temperature, humidity and other weather parameters; and,
 Diurnal variations in wind speeds and directions, as they are related to the variations
of air temperature, humidity and solar radiation throughout the day.

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Wu & Kriksic, (2012) describe about the use of achieved metrological data to draw out wind
speed diagram (Figure 6) for a Middle Eastern city. As shown in figure 6, on annual basis (a)
high winds approach from northwest direction with secondary winds from southeast. When
annual data is divided into different times during a day (b), there are high wind speeds
approaching from northwestern direction during midday and afternoon bringing in hot and
humid sea breezes at the speed of 9.0 – 10.0 m/s. These hot conditions are amplified by
solar radiations during midday and afternoon. However, when the sun is not up (morning,
evening, and night), low wind speeds are achieved. As seen, there is more orange and
green bands bringing in wind speeds of up to 6.0 m/s achieved from land breeze. These
types of wind are cold and not as humid ad midday and afternoon breeze.
Figure 6: Wind speed in a Middle Eastern city. (a) Annual speed, (b) daily variation of wind speed. (Ghosh &
Mittal , 2012)
2. Based on the data, CFD or wind tunnel test is conducted to predict theoretical wind
speed at pedestrian level.
There are a number of techniques used to determine wind at pedestrian level. However, the
two main techniques widely used are: wind tunnel testing; and computational fluid dynamics
(CFD) testing.
> Wind tunnel testing: Wind tunnel testing is said to be the best method to assess wind flow
at pedestrian level around tall buildings. There are two different types of methods available

16
which aid in assessing the environment near building’s vicinity. These are point method, and
area method. Point method provides the user with quantitative data where range of sensors
are placed around building parameters, recording wind speeds and temperature. Area
method on the other hand provides a continous qualitative data. This method makes use of
scour technique, where placed model (in wind tunnel) is coated with a uniformly thin layer of
particulate material. The wind speed is increased and left for some time till it reaches a
steady state. The results of this method demonstrates the wind speed is greater than or
equal to predetermind scour speed of material (Livesey, et al., 1990). Advantage of using
this method is that a complete overview of pedestrian wind level for the entire area is
provided.
The use of area method with scour technique is marked ideal for a complete test of wind
speed of an area. Scour technique is set out in two steps: (1) Prior to the placement of
model, turntable floor in wind tunnel is firstly covered with fine uniform layer of dried sand;
then, (2) after the placement of the model, another layer of fine sand is applied to the
turntable and the wind speed is increased in stages. Sand erosion occuring at each step of
wind speed is allowed to reach a steady state. Once the experiement is conducted, areas
with most sand erosion show that wind speed at pedestrian level is high.
Figure 7: Scour technique wind tunnel diagram (Blocken & Carmeliet, 2004).
Shown in diagram above, for each UWT value, there is a comparable UG and UGB value. UWT
denotes the speed of that is set by the operator/ user which is increased in steps until
reached a certain value. UG denotes ground level wind speed (not affected by building), UGB
denotes ground level wind speed influenced by building causing sand erosion.
Other techniques used within wind tunnel to gain wind speed at pedestrian level are:

17
> Oil streak: In oil streak technique, wind tunnel floor around the model is coated with a
mixture of kaolin and paraffin oil. Once the wind speed is increased, the oil moves in the
direction of the wind, on the turntable. Due to air flowing over the mixture, paraffin oil
evaporates leaving streak patterns showing direction of the wind flow around the building.
The shape and the density of the streak define the turbulance in the flow. This technique is
similar to scour technique which does not provide directional wind flow.
> Smoke visualisation: Smoke visualisation test is a technique that demonstrates the wind
flow around structure. Shown in Figure 8, is a smoke aided wind tunnel test. Two factors can
be visualised from the picture: (1) The flow of the smoke is divided into three parts. At 2/3’rd
of the height of the building, some of the divided smoke flows upwards, some passes
sideways, while the remaining flows downwards to the base; (2) The vortex generated
between the low and the tall building from the divisional downward smoke flow. This
technique is most adventageous as it reveals the direction of wind flow and any possibilities
of vortex.
Figure 8: Smoke aided wind tunnel technique (Blocken & Carmeliet, 2004).
> Computer Fluid Dynamics (CFD) testing: CFD is an alternative study of wind flow at
pedestrian level. With its advantages in being cheaper and less time consuming than wind
tunnel test and having the ability to demonstrate wind flow at any given moment providing in-
detail results, there is a major disadvantage. In order to be able to use CFD the model has to
be validated.

18
With growing demand on the use of CFD, there has been increase in publications by authors
such as Bert Blocken and Shuzo Murakami, and growing demand of this studty by architects
and engineers. Not having any limitations on the use over the method, the softwares have
been used by designers to test wind flow over vehicles, and many other products.
The use of CFD allows engineers to easily alter design criteria and other configurations. The
use of CFD is complex as a huge set of data has to be inputed in order to run the test, such
as: choosing of precise equation in order to test the flow, size of the computational model,
dimensions of the grid, boundry, etc.
As known, in order to test pedestrian wind flow around building, a validation has to be
required and in huge number of cases, it has not been achieved. Due to this restriction there
are few publication based on pedestrian wind flow with the aid of CFD. Recent research led
by (Blocken, et al., 2012) about wind safety and wind comfort for pedestrians in urban area
with the use of CFD, best practice guidelines were discussed. Differences between three
cases were discussed where wind comfort and wind safety studies were required (Blocken,
et al., 2012):
 Case 1: new developments within an existing urban configuration, for which on-site
measurements are available or will be conducted;
 Case 2: new developments within an existing urban configuration, for which no on-
site measurements are available or will be conducted;
 Case 3: development of a new urban configuration, for which – evidently – no on-site
measurements are available during the design stage.
2.3.WIND COMFORT CRITERIA
As previously discussed, wind speeds around tall buildings tend to vary from high to
average, from pedestrians feeling no effect to being blown over by gusts. Therefore, comfort
and discomfort can both be linked to this instance. With range of parameters involved, such
as: wind speeds, wind direction, temperature, humidity, etc. it is hard to calculate comfort
criteria for a particular area. It also depends on psycological factors such as regular change
in wind speeds, mean wind speeds, gustiness, wind speed occurance.
It is appropriate to calculate wind comfort criteria according to particualr pedestrian activity in
particular areas in combination frequencies of wind occurance or exceedance with certain
duration of time (Koss, 2006).

19
For a particular pedestrian activity, accepatable wind speed according to the comfort criteria,
ulim is to be defined. The general criteria assessing pedestrian’s location fulfills the
requirement for the intended utilisation or not shall comprise on the followinf two equations:
(1) Gust wind speed, ug = ū + g · σu ≤ulim
(2) Probability of exceedence, T
p(ug ≥ ulim) ≤ pcomfort
Shown above in equation 1, ū is mean wind speed, σu is the corresponding standard
deviation (represented by the rms value), p resembles the probability with
which ug exceeds ulim within a given period of time (T), and pcomfort is the maximum allowable
probability of exceedence for which a comfort level is achieved. Almost each parameter
contained in the two equations above differs from criterion to criterion, not only in value but
also in meaning (Koss, 2006).
There are various numbers of wind comfort criteria, designed and calculated by number of
authors. Presented below are few of many criteria discussed [two of the criterias have been
presented in this paper as Table 1 (pg. 10), and Figure 5 (pg. 12)].
PAC Description
A Sitting for a long period of time, laying steady position, pedestrian sitting, terrace,
street café or restaurant, open field theatre, pool
B Pedestrian standing, standing/sitting over a short period of time, short steady
positions, public park, playing field, shopping street, mall
C Pedestrian walking, leisurely walking, normal walking, ramble, stroll, walkway,
building entrance, shopping street, mall
D Objective business walking, brisk or fast walking, car park, avenue, sidewalk,
belvedere
Table 2: Definition of pedestrian activity categories (PAC) (Koss, 2006)
2.4.METHODOLOGY AND CONCLUSION
Bridgewater place being the only skyscraper in Leeds, generates wind tunnel effect causing
unfavourable experience for road users and has been involved in dangerous incedents since
its construction in 2007.

20
Bridgewater Place is located in the heart of Leeds, next to River Aire. Relating to Figure 1,
the high wind levels faced at the stagnation point of the building, divides into three sections
with high winds flowing downstream. This downastream flow was recorded to be between
67mph – 79 mph at pedestrian level. The effects from standing vortices led a lorry to be
toppled over to the side of the road causing death of a man. Relating to Table 1, the possible
wind speeds experienced at the location could be between breeze – gust with a dangerous/
hazardous wind speed as wind type.
Following the conclusion of this presented report, possible solution will be followed in order
to reduce wind speeds at pedestrian levels. The solutions provided will be shown to Leeds
council and also be referred to the given budget by the council.

21
20.2m
3. METHODOLOGY AND LIMITATIONS
As mentioned in abstract about the issues being caused by Bridgewater Place and a brief
mention of what the actual problem is, this chapter aims on showing how the mentioned
problems are caused.
The Bridgewater Place building located in Leeds has experienced high wind speeds at
pedestrian level since its construction completion in 2007. In windy circumstances, due to
high reflected wind on ground level, there has been junction closures. During these
conditions there has also been fatal incidents, one of with was a death of a man (BBC, 2011)
and the warning emails sent by council representative (BBC, 2013).
Experimental techniques are used to understand the current problem with the use of CFD
software such as Project Vasari.
3.1.CURRENT PROBLEMS
There are three different problems involved with the building: shape, location and orientation.
3.1.1. SHAPE
The building shape is divided into three sections, which are then conjoined to form the actual
structure. It is not only the shape but also the size of the building, which also matters when it
comes to wind interaction.
Section 1:
38.4m
18.2m 112m
Figure 9: Section one of Bridgewater Place (Gohil, 2014)
Shown in Figure 9 is the main section of the building located on the back side of the
structure, used for residential purposes. With the total height of building being 112m, the
building spans with the length of 38.4m and width of 18.2m. Due to this being the tallest
structure in Leeds, the wind reflected from the building surface does not travel well around

22
41.1m
64.7m
the structure, instead is downwash to ground level. An illustration of this is shown in figure
10.
Figure 10: Downwash wind after being reflected from building surface (Gohil, 2014)
Section 2:
84.1m
32.2m 37m
Figure 11: Section two of Bridgewater Place (Gohil, 2014)
Shown in figure 11 is the second section of Bridgewater Place. Located on the front face of
the entire structure, this particular building is used for office purposes. Since it being thefront
face of the building, the wind is blocked and diverted past it from the tallest section of the
structure.
Section Three:
8.2m
12.2m
64.7m
74.6m
18.3m 40m
Figure 12: Section three of Bridgewater Place (Gohil, 2014)
Shown in figure 12 is the third section of Bridgewater Place. This section is located on the
east side of the structure as a car park, dealing minimum damage. The wind downwash from
section one flows around on the ground level of the structure.

23
Entire Structure:
Figure 13: 2D and 3D viewpoint of Bridgewater Place (diagram not in scale) (Gohil,2014)
* Area shaded in purple resembles the joining section to form the entire structure
Section1
Section2
Section3

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3.1.2. LOCATION
Shown below in figure 14 and figure 15 as an example is wind direction in UK and Leeds.
Figure 14: Wind direction viewpoint (UK) (Met Office, 2014)
Figure 15: Wind direction viewpoint (Leeds) (Met Office, 2014)
As see in first images (fig. 14), the arrows resembling wind direction flow from eastern
direction to western; same goes with the zoomed version (fig. 15). The original location of
the Bridgewater Place is marked in black place marker on both maps.
In next section wind interaction with the building is to be explained in detail.

25
3.1.3. ORIENTATION
Figure 16: Bridgewater Place orientation against wind direction. (Google Maps, 2014)
The back and the right side of the building (section 1 and section 3) are facing the eastern
direction. Shown in figure 16 is the location of the building on a map along with arrows
resembling wind direction. As seen that the wind flows around the building when hit building
surface. This is due to its height, shape and orientation. The wind travelling towards the
building is deflected and forced to travel around when hit building surface. Taking other
building in consideration it can be seen that the wind flow is not interrupted at all.
3.2.USE OF CFD SOFTWARES
CFD softwares are used to achieve a full understanding of how a structure would
look and how it would react under possible loads, winds, solar radiation and energy
use. In order to get the aerodynamics of the building, CFD software Adobe Project Vasari
helps aid in precision of final results that are produced. In this case, Adobe Project Vasari is
the program used to test the building under computer-based wind tunnel.
3.2.1. ADOBE PROJECT VASARI
When testing the Bridgewater Place model onto this program against wind, the following
results are presented:

26
Figure 17: Original orientation of Bridgewater Place against wind. (Gohil, 2014)
Shown above in figure 17 is the original orientation of Bridgewater Place against wind
direction. As noticed from the image, the wind interaction with the building causes errors and
high wind point areas. The range of 0 m/s – 35 m/s was the wind speed considered for this
project, due to the highest wind speed recorded at the site was 79 mph (BBC, 2013). The
red sections seen on the image resemble the highest wind speed of 35 m/s.
Wind interactions with the building acts in different ways according to the building’s
orientation. Both figure 18 and 19 show that if the building was orientated 90° and 270° from
its original orientation, the flow achieved would have been better creating least to no issues.
Figure 18: 90° orientation of the building (Gohil,
2014)
Figure 19: 270° orientation of the building. (Gohil, 2014)

27
The red sections visible on the original figure have now been disappeared. This
demonstrates that the main area of issue in this situation is the orientation of the structure.
However, orienting the entire structure would be almost impossible.
Figure 20: Wind reaction when hit building surface (Gohil, 2014)
In order to understand the problem in a smart manner, figure 20 should how the building
reacts when wind is directed towards the building.
Shown in the above figure:
At point 1: The prevailing wind is directed towards the building surface from western to
eastern direction.
At point 2: The prevailing wind deflected off the building surface is flown to ground level, also
known as ‘downwash’.
At point 3: The prevailing wind from western direction travels around the building surface.
At point 4: The downwash wind from point 2 escapes onto water lane.
At point 5: Wind downwash from point 2 travels in backwards direction and wind travelling
along building surface on ground level causes mini vortices to form.
In order to design solution to the matter, point two and four are major concerns. It has to be
made sure that the downwash wind and wind escaping to Water Lane is minimised.
3
2
2
1
5 5
4

28
4. RESULTS
Two solutions were planned in order to cut down on wind speed at pedestrian level with
recommendation in use of two main elements – canopy and barriers. The designed solutions
were implemented onto the CAD image of Bridgewater Place and tested on Adobe Project
Vasari. The worked solutions are then analysed and compared back to the original state of
the building in the next chapter to see how the differences make changes to the pedestrian
wind environment.
As shown in previous chapter section 3.2.1. (pg. 26-28) on how wind travels around the
building with the main area to focus are at section 2, 4 and 5 (refer to figure 20).
4.1.SOLUTION 1
Figure 21: Solution 1 (Gohil, 2014)
Solution 1 implements the use of wind barriers. Breakers placed on the building face at each
floor breaks and deflects the wind; meaning there will be less wind speed on pedestrian
level. Barriers have also been placed on the building face at each floor for breaking and
deflecting of the wind travelling along the building face. Another barrier is placed on the
ground so the downwash wish escaping to Water Lane is deflected back upwards.

29
Figure 22: Solution one: (a) top view (b) western view (c) zoomed in view of the solution (Gohil, 2014)
a b
c

30
4.2.SOLUTION 2
Figure 23: Solution 2 (Gohil, 2014)
Solution 2 brings use of canopy and wind barriers. The canopy are placed from the back
face to the western face of the building. The downwash wind is deflected by the canopy and
preventing any sort of wind to reach ground level. Implementing the use of wind barriers on
top of canopy has a function of stopping and deflecting any wind that travels along the
canopy surface. This means that any wind travelling on canopy surface and escaping onto
Water Lane is prevented and deflected in various directions.

31
Figure 24: Solution two: (a) top view (b) western view (c) zoomed in view of the solution (Gohil, 2014)
c
ba

32
5. ANALYSIS
5.1.USE OF MATERIALS
The use of materials is important in designing the solution to the matter as different materials
react in a different manner to wind. With use of canopy and barriers, it is vital to make sure
that materials used for solution blend well with the building aesthetics and not diverse.
5.1.1. SOLUTION 1
The main element of this solution is the use of wind barriers. The wind barriers placed on
building surface at each level acts as wind breakers meaning the downwash wind is broken
and deflected. Similarly, the barrier placed on ground floor has same function along with
preventing remaining downwash wind to escape onto Water Lane.
The choice of material to be used for barriers placed throughout the structure is concrete.
Concrete is known to withstand high amount of pressers and deals well with wind. In an
article by Sauter, (2011) it was said by Joseph E. Salbia (provost at the University of Dayton
and former Dean of the School of Engineering) that while all natural disasters provide a
challenge, designing for wind “is the ultimate test for an engineer…”. To design for hurricane
and tornado proof buildings across the world, concrete is widely acknowledged, withstanding
wind speeds of more than 70 mph. At current stage, the highest wind speed recorded at
Bridgewater Place was of 35 m/s equivalent to 78 mph (BBC, 2011).
Initial plan involves in placing concrete beams and concrete elements on the building face,
leading up to the building’s stagnation point. A stagnation point of the building is located at
building’s approximately 70% of the height where wind is deflected into multiple directions
(refer to figure 1); for Bridgewater Place, the stagnation point is approximately located at the
height of 78.4m which is up to 23rd
floor.

33
5.1.2. SOLUTION 2
This solution implements the use of canopy and barriers. Canopy spread from the back face
to the western face of the building along with wind barriers installed on top of these canopy
at the back face. The downwash wind from stagnations point is deflected after reaching
canopy surface and wind travelling along the canopy surface is deflected by barriers,
preventing it to escape to Water Lane. Below, figure 25 shows an example of how wind
travels around a structure after installing a canopy; similar idea is applied to solution 2.
Figure 25: Wind travel around a structure after installation of canopy (Gohil, 2014)
The choice of material to be used for canopy and barriers is glass and metal. With different
range of materials, it is believed that glass and metal improves the overall look of a structure.
With not only aesthetical features as an advantage, glass is an easy material to clean and
maintain. Implementing of glass canopy involves high standard regulation manufacture,
minimising the chances of failing of material. The material is also affordable and perceptible
than concrete.
5.2.AESTHETICS
5.2.1. SOLUTION 1
As previously mentioned, solution one implements the use of wind barriers along the building
face and on ground level. The building has a high use of glass and concrete and the use of
concrete for the solution is an ideal option. With the dimension of the barriers on building
face for breaking down downwash wind is: 5m x 0.3m x 0.5m and the dimension of the
barriers on the building face to break and deflect wind travelling along building face is 0.3m x
1.5m x 0.5m along with , the wind barriers will blend in well with Bridgewater Place.

34
The barrier placed on the ground floor of the building between the building back face and
water lane has dimensions of. 7m x 5m x 1m. The barrier can also be used to provide a
pleasant welcome to users and advertise Bridgewater Place logo on the wall facing Water
Lane.
5.2.2. SOLUTION 2
The use of glass canopy and barrier for solution two gives a vibrant feel. With its function of
protecting pedestrians from high wind speeds, the canopy add a modern look to the building.
Glass canopy can also be installed with LED lights improving its overall quality during night
hours.
5.3.COMPARISON TO CURRENT SITUATIONS
5.3.1. SOLUTION 1
Shown in figure 22 is the solution two tested on CFD program. The highest wind speed
recorded was 13.8 m/s. Compared to the original of 35 m/s the difference of 21.2 m/s is
good and the hazardous red flow lines on water lane have now turned orange/ dark green.
However, the wind speed recorded is still harsh on water lane and can be cut down further
for pedestrian safety.
5.3.2. SOLUTION 2
Figure 24 demonstrates solution two under CFD test. The highest wind speed recorded was
6.2 m/s. Compared to the original of 35 m/s the difference of 28.2 m/s and 7.2 m/s against
solution one shows improvement. The hazardous red lines appearing on water lane (figure
17) and orange/ dark green (figure 22 a) have turned into bright green/ dark blue.
5.4.PREFOUND SOLUTION
Prior to designing and planning solutions for the current problem at Bridgewater Place, CPPI
unveiled the wind reduction scheme. The solution consists the use of canopy, barriers and
wind baffles.

35
5.4.1. PROPOSED SOLUTION AND PLANS
The proposed scheme implements the use of four perforated wind baffles with the
dimensions of 20m x 4m and will be supported 6m above road level in order for all vehicle
access. Prevailing wind flowing from western direction is broken and deflected through each
baffle allowing minimum wind to pass through by Wind Baffle A. The design also implements
the use of three perforated wind barriers. Three barriers will be placed along the building
with the height ranging from 12m – 18m for another small barrier placed on the eastern face
of the building with the height of 4m. Along with baffles and barriers, the design also
comprises with glass canopy from the back face to the western face of the building
protecting the entry and exit points to Bridgewater Place (Bridgewater Place, 2014). Figure
26 and 27 shows the proposed design in detail. The highest wind speed achieved at the site
was 5.3 m/s.
As per plans, CPPI are currently in process of finalising the design while taking feedbacks
and reviews for the published scheme. Once finalised, the scheme will be forwarded to
Leeds County Council in order for approval to construct.
Figure 26: Bridgewater Place wind reduction proposal (Bridgewater Place, 2014)

36
Figure 27: 3d view of Bridgewater Place wind reduction scheme (Bridgewater Place,2014)
Figure 28: Proposed solution: (a) top view (b) western view (c) zoomed in view of the solution (Gohil, 2014)
c
a b

37
6. DISCUSSION
Understanding the difference in microclimate by Bridgewater Place, possibility of relation
between building’s shape, location and orientation and the wind speed at pedestrian level is
investigated. In order to test the wind aerodynamics, highest wind speed recorded at the
location is used for testing. The results to the investigation are shown above in chapter 4 and
5 with a clear understanding on wind distribution and wind flow before and after the solution.
However, In this chapter, the presented results are discussed for and against the research
found in chapter 2, 3 and 5.
6.1.HYPOTHESIS AND CURRENT STUDY
Bridgewater Place is an office and a residential structure built in 2007. Since its construction
the building has been involved in various incidents about high wind speeds recorded at
ground level such as; death of man due to lorry toppling over (BBC, 2011), woman severely
injured when walking past the building (BBC, 2013), woman left with torn liver and internal
bleeding due to high wind speeds (BBC, 2013). The aim of this dissertation was to
understand and design a viable solution to pedestrian wind problems.
When designing the solution it was vital to understand the current problem for which a 3D
model was designed on CAD software and then uploaded onto CFD program. The areas
and the problems were then highlighted to which solutions were designed (pg. 28-31).
In order to design solutions, aerodynamics flow were considered. Based on journal produced
by Blocken & Carmeliet, (2004) wind and pressure distribution were understood and tested
onto Bridgewater Place aiding in clear understanding of building’s stagnation point and wind
and pressure distribution. Based on research produced by Amin & Ahuja, (2010) the use of
drag forces and lift forces were considred. Drag froces were considered at the building’s
stagnation point in order to witness on how the structure reacts the pressure distribution.
Tested on CFD program, Bridgewater Place produced positive results on dealing with
oncoming wind, part of wind flown around the structure. Lift forces were considered after the
pressure distribution form stagnation point. During pressure distribution high wind speeds
were recorded to be downwashing causing high damage at pedestrian level. Minimal amount
of wind was flown in the upwards direction to join mean wind direction.
Highest wind speed recorded at site was 35 m/s to which two solutions were designed to
control the wind speed at pedestrian level. Solution 1 resulted with 13.8m/s as the highest

38
wind speed with implementation of wind barriers installed on building face. On the other
hand, solution 2 resulted with 7.2m/s as the highest wind speed with implementation of
canopies and wind barriers.
Refereeing the data to table 1 presented by Baniotpoulos, et al., (2011), original wind speed
of 35m/s is considered dangerous and hazardous with strong gale. Solution 1 presents
harsh wind type with strong breeze experienced by pedestrians. Solution 2 on the other
hand presents a moderate breeze resulting in minimum damage caused to pedestrians.
6.2.COMPARISON BETWEEN FOUND SOLUTION AND CPPI SOLUTION
Following the completion of literature review, CPPI (owner of Bridgewater Place) unveiled
the proposed plans on ongoing high wind speed at pedestrian level caused by building
aerodynamics on 8/02/2014 (BBC, 2014). With aid of wind baffles along water lane, barriers
and canopy the wind speed at Leeds’ skyscraper were set to minimise.
In order to understand how successful the solution is, a 3D model was designed and tested
on a CFD software and the results achieved (pg. 35 - 36) were similar to user found
solutions. The highest wind speed achieved at the site was 5.3 m/s with a difference of 1.9
m/s compared to solution 2. CPPI successfully produced a better result however; concerns
were raised by public on the time frame of construction of the solution. The proposed
solution plans to take almost two years to construct protecting pedestrian and other road
users from high wind speeds. On the other hand, it is believed that the installation of wind
baffles along water lane not only increase the construction time frame but also increases the
overall cost of the project. When compared to solution 2, the installation of canopy and wind
barrier takes less time with lower overall cost.

39
7. CONCLUSION
Based on knowledge gained on the literature of structure aerodynamics and the effect of
wind, this dissertation successfully presents the working of Bridgewater Place and an
attempt of minimising wind speed at pedestrian level. This dissertation implements the use
of CFD program “Adobe Project Vasari” to test on wind speed and wind distribution around
the designed structure and the understandings gained can be applied to the vicinity in order
to gain the overall effect of the wind in the area. The specific aims and objectives of this
project were to gain a clear understanding of building aerodynamics in order to design a
viable solution to the matter.
A complex correlation between wind and aerodynamics is discovered. Multiple factors need
to be taken in count when designing for wind speed problems. First, mean wind speed, wind
direction and building shape, location and orientation are considered following which
stagnation points are discovered defining wind distribution and pressure fluctuations. These
points help understand the areas of concerns to which solutions are designed. For
Bridgewater Place, it was understood that the main area of concern was caused by the
downwash wind and the flowing of wind in Water Lane to which solutions are presented.
However further work can be put into the project to test the model in a traditional wind tunnel
to compare and contrast between both methods resulting in more accurate solutions.
Finally, this type of method can be used by professionals to understand wind flow around
multiple structures and objects but due to risks involved in trying the method first time has
resulted in following the tests and results produced in a traditional wind tunnel. Through this
case study, they are now able to understand the advantages and disadvantages in using
CFD program and wind interaction with a structure.

40
8. REFERENCES
American Society of Civil Engineers, 1989. Outdoor Human Comfort and Its Assessment:
The State of the Art. Montreal: American Society of Civil Engineers.
Amin, J. A. & Ahuja, A. K., 2010. AERODYNAMIC MODIFICATION TO THE SHAPE OF
THE BUILDINGS: A REVIEW OF THE STATE-OF-THE-ART. Asian Journal of Civil
Engineering (Building and Housing), 11(4), pp. 433-450.
Aynsley, R. M., 1989. Politics of pedestrian level urban wind control. Building and
Environment, 24(4), pp. 291-295.
Baniotopoulos, C. C., Borri, C. & Stathopoulos, T. eds., 2011. Extended Land Beaufort Scale
shwoing wind effects on people (Lawson and Pendwarden 1975; Isyumov and Davenport
1975). In: Environmental Wind Engineering and Design of Wind Energy Structures. Wein:
Springer, p. 10.
BBC, 2011. Wind death in Leeds prompts tower safety fears. [Online]
Available at: http://www.bbc.co.uk/news/uk-england-leeds-12717762
[Accessed 29 11 2013].
BBC, 2013. Birstall woman injured by wind at Leeds skyscraper. [Online]
[Accessed 23 01 2014].
BBC, 2013. Bridgewater Place 'wind tunnel caused Leeds injuries'. [Online]
[Accessed 12 12 2013].
BBC, 2013. Bridgewater Place: Council official warned of wind fears. [Online]
[Accessed 17 02 2014].
BBC, 2014. Bridgewater Place wind reduction plans go on show. [Online]
[Accessed 2014 02 09].
Beyers, M. & Waechter, B., 2008. Modeling transient snowdrift development around complex
three-dimensional structures. Journal of Wind Engineering and Industrial Aerodynamics,
96(10-11), p. 1603–1615.

41
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43
9. APPENDIX 1: SUPERVISOR SIGN OFF SHEET
Date Subjects discussed Progress since last
meeting
Signature
02/10/13  Possible dissertation
topics.
 General field of study.
 Case study discussions.
 Lab based experiment
discussion.
10/10/13  Dissertation topic finalised.  Researching
dissertation topic.
18/10/13  Draft outline check.
 Improvements to make.
 Update on Bridgewater
Place.
 Project outline written.
05/11/13  Outlining interim report.  n/a
08/11/13  Finalising on topics to
cover in interim report.
 Topics and subtopics
laid out for interim
report.
13/11/13  Interim report progress
check.
 Interim report writing.
check.
check.
02/12/13  Draft interim report check.  Interim report writing.
12/12/13  Finalising interim report.  Improvements added to
draft interim report.
09/01/14  Discussion about topics to
cover in presentation.
 n/a
23/01/14  Outlining final report.  n/a
04/02/14  Presentation progress
check.
 Final report progress
check.
 Starting of final report
writing.
20/02/14  Discussion about the
unveiling of CPPI solution.
 Final report writing.
06/03/14  Draft presentation check.  Final report writing.
 Presentation writing.
19/03/14  Finalising presentation.  Presentation writing.
10/04/14  Draft final report check.  Final report writing
29/04/14  Finalising final report.  Improvements added to
final report.
Completion Date Component % of total module marks
25th
Oct 2013 Outline Pass/Fail
13th
Dec 2013 Interim Report 20
Feb 2014 Oral Presentation 10
01th
May 2014 Final Report 70

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