can wind be incorporated in future buildng design? prepared by elif kandiyoti
TRANSCRIPT
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Can wind be incorporated in future building design?
How to increase productivity by design?
by
Elif Kandiyoti
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Can wind be incorporated in future building design?
How to increase productivity by design?
Abstract: All researches show how population and respectively energy demand grow. We
have to produce electricity to supply this demand. As we learn from Energy and Environment
courses lectures, we lose 1/3 of energy we generate in transmission line. This indicates that we
have to generate electricity as close as possible to where we live. According to the United
Nations Environment Program, in 1950 fewer than a third of the people of the world lived in a
town or city, while today almost half of the worlds population is urban, and the forecasts are
that in just 20 yearsby 2030almost two-thirds of the people will live in cities and towns
(Botkin, p 499). In large cities, land is limited and expensive; as a result buildings go vertically
instead of horizontally. Thus we will look closely to tall buildings in cities. Moreover, the
increasing concerns over environmental issues and the depletion of fossil fuel demanded the
search for more sustainable electrical sources. One technology for generating electricity from
renewable resources is to use wind turbines that convert the energy contained by the wind into
electricity. The wind is a vast, worldwide renewable source of energy. Since ancient times,
humans have harnessed the power of the wind (Muyeen, p14). Now we should look at what we
can do with todays technology and knowledge in tall buildings.
Before implementing any turbine to anywhere we have to comprehend all aspects of
wind energy from macro level to micro level in order to achieve optimum results. Unsuccessful
applications of turbines can harm winds reputation. Thus we have to make feasibility study as
early as possible. In this paper, we will cover all aspects of wind energy from wind flows to
building shape, wind energy history, wind flows and its differences in rural and urban areas,
wind turbines and their environmental impacts.
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Wind History: The wind is a free, clean, and inexhaustible energy source. It has served
mankind well for many centuries by propelling ships and driving wind turbines to grind grain
and pump water. Wind was almost the only source of power for ships until Watt invented the
steam engine in the 18th Century. Denmark was the first country to use the wind for generation of
electricity. The Danes were using a 23 m diameter wind turbine in 1890 to generate electricity.
By 1910, several hundred units with capacities of 5 to 25 kW were in operation in Denmark.
About 1925, commercial wind-electric plants using two- and three-bladed propellers appeared on
the American market. The most common brands were Wincharger (200 to 1200 W) and Jacobs
(1.5 to 3 kW). These were used on farms to charge storage batteries which were then used to
operate radios, lights, and small appliances with voltage ratings of 12, 32, or 110 volts. A good
selection of 32 Vdc appliances was developed by industry to meet this demand. Then the Rural
Electric Administration (REA) was established by Congress in 1936. Low interest loans were
provided so the necessary transmission and distribution lines could be constructed to supply
farmers with electricity. In the early days of the REA, around 1940, electricity could be supplied
to the rural customer at a cost of 3 to 6 cents per kWh. The corresponding cost of wind generated
electricity was 12 to 30 cents per kWh when interest, depreciation, and maintenance were
included. The lower cost of electricity produced by a central utility plus the greater reliability led
to the rapid demise of the home wind electric generator (Johnson, p1-3).
What is wind: Wind results from the movement of air due to atmospheric pressure
gradients. Wind flows from regions of higher pressure to regions of lower pressure. The larger
the atmospheric pressure gradient, the higher the wind speed and thus, the greater the wind
power that can be captured from the wind by means of wind energy-converting machinery. The
generation and movement of wind are complicated due to a number of factors. Among them, the
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most important factors are uneven solar heating, the Coriolis effect due to the earths self-
rotation, and local geographical conditions ( Muyeen, p 4).
There are 6 characteristic of wind. Understanding them will help us to optimize wind
turbine design, develop wind measuring techniques, and select wind farm sites (Tong, p 12).
1-Wind Speed: Wind speed is one of the most critical characteristics in wind power generation.
In fact, wind speed varies in both time and space, determined by many factors such as
geographic and weather conditions. Because wind speed is a random parameter, measured wind
speed data are usually dealt with using statistical methods (Tong, p 12).
2 Weibull Distribution; The variation in wind speed at a particular site can be best described
using the Weibull distribution function which illustrates the probability of different mean wind
speeds occurring at the site during a period of time (Tong, p 12).
3- Wind Turbulence: Wind turbulence is the fluctuation in wind speed in short time scales,
especially for the horizontal velocity component. Wind turbulence has a strong impact on the
power output fluctuation of wind turbine. Heavy turbulence may generate large dynamic fatigue
loads acting on the turbine and thus reduce the expected turbine lifetime or result in turbine
failure (Tong, p 12).
4- Wind Gust: Wind gust refers to a phenomenon that a wind blasts with a sudden increase in
wind speed in a relatively small interval of time. In case of sudden turbulent gusts, wind speed,
turbulence, and wind shear may change drastically (Tong, p 12).
5- Wind Direction: Statistical data of wind directions over a long period of time is very important
in the site selection of wind farm and the layout of wind turbines in the wind farm. The wind rose
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diagram is a useful tool of analyzing wind data that are related to wind directions at a particular
location over a specific time period (year, season, month, week, etc.) (Tong, p 12).
6- Wind shear: Wind shear is a meteorological phenomenon in which wind increases with the
height above the ground. The effect of height on the wind speed is mainly due to roughness on
the earths surface (Tong, p12).
Wind does not flow smoothly over the Earths surface. It encounters resistance, known as
friction. This is called ground drag. Ground drag is caused by friction when air flows across a
surface. Friction is the force that resists movement of one material against another. When wind
flows across land or water, friction occurs. This reduces the speed at which air moves over a
surface. Ground drag due to friction, however, varies considerably, depending on the roughness
of the surface. The rougher or more irregular the surface, the greater the friction. As a result, air
flowing across the surface of a lake generates less friction than air flowing over a meadow. Air
flowing over a meadow generates less friction than air flowing over a forest. Friction extends to
a height of about 1,650 feet (500 meters). However, the greatest effects are closest to Earths
surfacethe first 60 feet over a relatively flat, smooth surface. Over trees, the greatest effects
occur within the first 60 feet (18 meters) above the tree line. Friction has a dramatic effect on
wind speed at different heights. For instance, a 20-mile-per-hour wind measured at 1,000 feet
above land covered with grasses flows at 5 miles per hour 10 feet above the surface. It then
increases progressively until it breaks loose from the influence of the ground drag or friction.
Ground drag dramatically influences wind speed near the surface of the ground where residential
wind generators are located (Chiras, p 24).
Because the effects of friction decrease with height above the surface of the Earth, savvy
installers typically mount their wind machines on towers 80 to 120 feet high (24 to 37 meters), or
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even as high as 180 feet (55 meters) in forested regions, so their turbines are out of the most
significant ground drag. At these heights, the winds are substantially stronger than near the
ground. As discussed shortly, a small increase in wind speed can result in a substantial increase
in the amount of power thats available from the wind and the amount of electricity a wind
generator produces. Mounting a wind turbine on a tall tower therefore maximizes the electrical
output of the machine. Placing a turbine on a short tower has just the opposite effect (Chiras, p
24). In figures below, we can see friction affects in different regions.
Figure1: Friction in meadow, Figure 2: Friction in forest
Source: Wind Power Basics (p 26) Figure 3: Friction in urban environment
Another natural phenomenon that affects
the output of most wind turbines is turbulence.
Turbulence is produced as air flowing across the
Earths surface encounters objects, such as trees
or buildings. They interrupt the winds smooth
laminar flow, causing it to tumble and swirl, the same way rocks in a stream interrupt the flow of
water. Rapid changes in wind speed occur behind large obstacles and winds may even flow in
the direction opposite to the wind. This highly disorganized wind flow is referred to as
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turbulence. Turbulent wind flows wreck havoc on wind machines, especially the less expensive,
lighter-weight wind turbines often installed on short towers. Turbulence also causes vibration
and unequal forces on the wind turbine, especially the blades that may weaken and damage the
machine. Turbulence, therefore, increases wear and tear on wind generators and, over time, can
destroy a turbine. When considering a location to mount a wind turbine, be sure to consider
turbulence-generating obstacles. Proper location is the key to avoid the damaging effects of
turbulence. Turbulence can also be minimized by mounting a wind turbine on a tall tower
(Chiras, p 25).
After we have enough knowledge on wind, we have to evaluate availability of local wind
in our site from macro scale to micro scale. At macro level, the main factor, the annual mean
wind speed. In US, there is an 80-meter (m) wind resource map to identify potentially wind sites,
provided by The U.S. Department of Energy. In other countries, this can be available at local
weather stations. Annual mean wind is equal to the sum of the hourly average values for the
whole year divided by 8760 (the number of hours in a year). The mean wind speed will depend
on many factors such as the location in relation to dominating global wind currents, the distance
from the coast, the amount of upstream roughness that the winds have to travel over to reach
the site as well as other conditions such as the altitude of the site (Stankovic, p 85).
After finding enough information about adequate wind resources in our region, we can
determine if our area of interest should be further explored. Wind resource at a micro level can
vary significantly; therefore, we should get a professional evaluation of our specific area of
interest. Besides professional evaluation, knowing wind flows in urban area can help us design
our building suits in its local climate. When our interest is a tall building in urban environment,
our focus will be on cities climate.
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Cities affect the local climate; as the city changes, so does its climate. Cities are generally
less windy than nonurban areas because buildings and other structures obstruct the flow of air.
But city buildings also channel the wind, sometimes creating local wind tunnels with high wind
speeds. The flow of wind around one building is influenced by nearby buildings, and the total
wind flow through a city is the result of the relationships among all the buildings. Thus, plans for
a new building must take into account its location among other buildings as well as its shape
(Botkin, p 509).
Urban environment affects wind velocity in a few ways. Buildings cast shadows and act
as barriers to wind and create channels which increase wind velocity: The bulk of two buildings
of differing size adjacent to one another affects wind flows so strongly that the downward flow
of air on the taller block creates higher wind speeds in two zones (Thomas, p 25, 116).
Figure 4 and 5 at below illustrates how the differing arrangement of simple buildings can
disturb the wind flow, generate varying wake patterns and induce swirling turbulent flow. When
siting turbine in an urban environment these disturbed flow zones should be identified and
avoided. This is commonly achieved by ensuring the blades of the turbine are sufficiently
elevated above roof level. Generally, the disturbed flow region in the isolated roughness flow
case is considered to be twice the height of the obstacles. Therefore turbine blades, generally,
should be located twice the height of the tallest local obstacle to avoid a significant drop in
potential performance. There are cases where the acceleration near building can be used to gain
an advantage but usually if the building has not been carefully designed with wind energy in
mind this should be avoided. The wake region in the isolated roughness case is considered to
extend to between 10 and 20 times the obstacle height (Stankovic, p 76).
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Figure 4: Undisturbed Regions shows wind flow in urban environment and places to
avoid installing wind turbine. Source: Urban Wind Energy (p 77)
Figure 5: Optimal turbine heights in undisturbed regions to avoid from turbulent region.
Source: Urban Wind Energy (p 77)
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Wind Turbines: After having knowledge on wind flows, we have to look closely how
turbines work. Before we choose a turbine we should know that every turbine is not equal. They
give different results in different conditions. Decision should be made according to wind data of
our site.
A modern wind turbine is an energy-converting machine to convert the kinetic energy of
wind into mechanical energy and in turn into electrical energy. Wind turbines can be classified
according to the turbine generator configuration, airflow path relatively to the turbine rotor,
turbine capacity, the generator-driving pattern, the power supply mode, and the location of
turbine installation (Tong, p15).
There are two ways to convert wind energy into mechanical power in the rotor axis: drag-
driven rotor, a lift-driven rotor or a combination of both concepts: the hybrid rotor. The
conversion mechanism of wind power into mechanical power of the lift-driven and drag-driven
rotor is different. A lift-driven wind turbine can be a horizontal axis wind turbine (HAWT) or a
vertical axis wind turbine (VAWT). The drag-driven wind turbines have a vertical axis. The
driving force of the drag-driven rotor originates from the difference in drag of (rotating) bluff
bodies. The projected blade area of the drag-driven rotor is approximately equal to the rotor area.
The projected blade area of the lift-driven rotor is a fraction of that area (Merten, p 6).
Figure 6: Drag and Lift forces. Sources:
CATs
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Most commercial wind turbines today belong to the horizontal-axis type, in which the
rotating axis of blades is parallel to the wind stream. The advantages of this type of wind turbines
include the high turbine efficiency, high power density, low cut-in wind speeds, and low cost per
unit power output. On the other hand the blades of the vertical-axis wind turbines rotate with
respect to their vertical axes that are perpendicular to the ground wind turbine. A significant
advantage of VAWT is that the turbine can accept wind from any direction and thus no yaw
control is needed. Since the wind generator, gearbox, and other main turbine components can be
set up on the ground, it greatly simplifies the wind tower design and construction, and
consequently reduces the turbine cost. However, the vertical-axis wind turbines must use an
external energy source to rotate the blades during initialization. Because the axis of the wind
turbine is supported only on one end at the ground, its maximum practical height is thus limited.
Due to the lower wind power efficiency, vertical-axis wind turbines today make up only a small
percentage of wind turbines (Tong, p 16).
Based on the configuration of the wind rotor with respect to the wind flowing direction,
the horizontal-axis wind turbines can be further classified as upwind and downwind wind
turbines. The majority of horizontal-axis wind turbines being used today are upwind turbines, in
which the wind rotors face the wind. The main advantage of upwind designs is to avoid the
distortion of the flow field as the wind passes though the wind tower and nacelle. For a
downwind turbine, wind blows first through the nacelle and tower and then the rotor blades. This
configuration enables the rotor blades to be made more flexible without considering tower strike.
However, because of the influence of the distorted unstable wakes behind the tower and nacelle,
the wind power output generated from a downwind turbine fluctuates greatly. In addition, the
unstable flow field may result in more aerodynamic losses and introduce more fatigue loads on
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the turbine. Furthermore, the blades in a downwind wind turbine may produce higher impulsive
or thumping noise (Tong, p 17).
In a summary, there are 3 turbine types:
Vertical Axis Wind Turbine (VAWT), Darrieus (2 Blades, 3 Blades, and H-Rotor), Savonius,
and Alternative Designs (Helical, MagLev).
Horizontal Axis Win Turbine (HAWT) 1 Blade, 2 Blades, 3 Blades and more, windmill, Co-
Axial multi rotor.
Other types are Aerial/Floating and Wind Belt.
Figure 7: Horizontal Axis Wind Turbine and
Vertical Axis Wind Turbine. Source: CATs
Figure 8: Horizontal Axis Wind Turbine Components. Source:
CATs. Figure 9: Vertical Axis Vind Turbine types. Source:
Wind Power Generation and Wind Turbine Design. (p 17)
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In the built environment, we are looking for the higher buildings to site our wind turbine.
Moreover, a wind turbine sited between buildings suffers from turbulence and the resulting
frequent changes in wind direction and high fatigue load. Such high fatigue load is coupled with
the probability of damaging the wind turbine and the risks for trespassers that could be hit by
(part of) a fractured blade. Furthermore, the frequent changes in wind direction cause frequent
yawing of a HAWT so that the HAWT is hardly aligned with the flow. Such average
misalignment causes a drop in energy yield. A VAWT is better suitable to perform in such
turbulent environment, as yawing is not required for a VAWT. But the rotor size of the VAWT
should be small in order to avoid the unsteady effects coupled with frequent changes in wind
direction and in order to profit from the local speed up close to buildings (Merten, p 168).
Secondly, the concentrator effect of the building in combination with the wind rose
should be considered. The concentrator effect of the building should fit the wind rose.
Acceleration of the undisturbed wind speed by the building for only one wind direction and
deceleration for all other wind directions in an omni-directional wind climate is not very
profitable for the energy yield (Merten, p 168).
Thirdly, the most suitable wind turbine for the site should be chosen. Compared to drag
driven wind turbines, lift driven wind turbines have better prospects to become economic. The
choice between a VAWT and a HAWT depends nevertheless on several additional issues. The
frequent wind direction changes in the built environment are already mentioned. On roofs of
sharp edged buildings the flow angle should also be considered. The flow direction close to the
edges of a sharp edged building is not parallel to the roof and as a consequence, a HAWT in that
flow from below shows a power drop compared to a HAWT in horizontal flow. The power
output of a small H-Darrieus or lift driven VAWT increases in flow from below. The H-Darrieus
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is therefore preferred for that flow. For concentrator buildings such as the plate concentrator and
the shrouded configuration, the HAWT is preferred because the rotor of an H-Darrieus is not
able to extract power from the total rotor surface (Merten, p 168).
On-grid and off-grid wind turbines: Wind turbines can be used for either on-grid or off-
grid applications. Most medium-size and almost all large-size wind turbines are used in grid tied
applications. One of the obvious advantages for on-grid wind turbine systems is that there is no
energy storage problem. As the contrast, most of small wind turbines are off-grid for residential
homes, farms, telecommunications, and other applications. However, as an intermittent power
source, wind power produced from off-grid wind turbines may change dramatically over a short
period of time with little warning. Consequently, off-grid wind turbines are usually used in
connection with batteries, diesel generators, and photovoltaic systems for improving the stability
of wind power supply (Tong, p18).
Safety is one of the most important concerns in wind turbines. We have to control turbine
under any severe weather condition such as tornedo for reliable and safe operation. Under high
wind speed conditions, the power output from a wind turbine may exceed its rated value. Thus,
power control is required to control the power output within allowable fluctuations for avoiding
turbine damage and stabilizing the power output. The main control systems in a modern wind
turbine include pitch control, stall control (passive and active), yaw control, and others. Two
primary control strategies in the power control: pitch control and stall control (Tong, p 24).
Turbine operation is another aspect we have to know. Wind speed is related to turbine
operation.
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Cut-in wind speed: At this speed the wind provides enough force to begin to turn the
blades. The value depends on the blade design and the friction-generating elements of the drive
train (Stankovic, p 72).
Start up wind speed: At this speed the blades are moving fast enough, and are capable of
transferring enough torque to the drive shaft, to enable useful electricity to be generated. At this
speed the generator will start to operate and produce useful electricity. Although the start-up
wind speed can be very close to the cut-in speed they are not the same. For example, the Bergey
XL1 turbine has a cut-in speed of 2.5m/s; however, the start-up wind speed is just over 3m/s.
Although the turbine may be able to generate some electricity at 2.5m/s it may not be compatible
with the electrical grid (Stankovic, p 72).
Minimum annual mean wind speed: The annual mean wind speed is simply the wind
speed at a certain location averaged over a year. If the annual mean wind speed at a site is equal
or greater than the designated minimum annual mean wind speed, there will be enough energy
in the wind on an average basis to begin to consider the idea of where the technology will move
from unfeasible to feasible, a useful value to keep in mind is a minimum annual mean wind
speed of 5.5m/s. It should be noted that this refers to the average speed of the wind at the turbine
hub height which could be, for example, 70m or more and not the general site speed, which may
have been taken from a standard weather station with an anemometer 10m above ground level
(Stankovic, p 72).
Rated wind speed: This corresponds to the maximum energy the turbine can extract from
the wind. The rated wind speed is sometimes referred to as the name plate value as this is the
peak value quoted when referring to a particular turbine. Beyond this wind speed the turbine will
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either passively or actively reduce the percentage of energy it will extract from the wind in order
to prevent damage to the device (Stankovic, p 72).
Cut-out wind speed: At this speed the wind turbine will stop turning completely in order
to prevent damage to the turbine. This cut-out speed is usually quite high, such as 25m/s, and
will rarely occur on most sites (Stankovic, p 72).
One other wind speed term to consider is the storm-rated wind speed (or survival wind
speed). This can be critical for an urban wind turbine if winds are being deliberately accelerated
(Stankovic, p 72).
Table 1: Typical values for key wind speed. Source: Urban Wind Energy (p 73)
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Design case: In building environment wind has positive and negative effects, many of
which are subjectively evaluated. For the structural engineer of highrise, wind effect is a
negative factor that inflates construction costs. For urban planner, wind has a positive effect as a
result of carrying off contaminants and a negative effect by diminishing the comfort of
pedestrians. For fire protection experts, the impact of wind on guaranteed smoke extraction in
case of fire in high rise. (Eisele Page 117) Moreover, according to Carbon Trust A Natural
Choice Natural Ventilationbooklet, Natural ventilation systems supply fresh air and remove
excess heat, odor, CO2 and other contaminants. We can benefit from all departments experience
when we evaluate wind for design. Sometimes we can use it to reduce energy consumption,
sometimes for reducing material usage.
When we design buildings it is important to reduce energy use before generating it.
Building orientation with the respect of solar angle and wind flow direction can utilize the
natural ventilation, lighting and heating thus can reduce a significant amount of energy use and
cost. (Afrin, p 67) After reducing energy consumption, we should design our buildings to take
advantage of on side renewable energy. In this case, it is wind energy.
Orientation of building is the core of the design. Every site has different constricts that
affects its orientations. Sun and wind are two of them. Wind is an important aspect not only for
generating electricity but also for structure of the buildings. Even though, we dont install a
turbine to our building we have to know how our buildings are affected by wind load. Which
direction wind comes from, which direction it goes. From how many directions it comes to our
site. In order to understand wind direction, we can use wind rose. Wind rose gives a very
succinct but information-laden view of how wind speed and direction are typically distributed at
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a particular location. Presented in a circular format, the wind rose shows the frequency of winds
blowing from particular directions. (NRCS)
Figure 10: Building orientation considering wind load. Source: HighRise Manuel: Typology
and Design, Construction and Technology (p 118)
Now it is time to install a wind turbine to our buildings. There are two important criteria
when installing a wind turbine to a building. The first one is the place we put the turbine, second
is how to shape the building to accelerate natural wind speed which hit the turbine. For optimum
result, it is important to shape the building with wind energy in mind. With the right shape,
turbine efficiency can be improved significantly. Generally, there are 6 different ways to
integrate a turbine to a building. They have their advantages and disadvantages. We will only
compare them with their wind acceleration which affects turbine efficiency. Before making any
design decision, you should consider all affects. (Stankovic, p 160)
1. This option primarily takes advantage of the opportunity to access higher qualitywinds that tend to exist at greater altitudes. These winds will not only have a relatively
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high energy content but are also likely to be less turbulent. However, there will be a
degree of natural wind acceleration with a ~10 per cent energy increase for the natural
wind acceleration alone (Stankovic, p 160) We can see lots of examples of this option.
2. This option takes advantage of the higher quality winds at higher altitudes andadditional local acceleration with a ~15 per cent energy increase for the local wind
acceleration The rounded faade will mean the tower height can be much lower
(Stankovic, p160).
3. This option takes advantage of the higher quality winds at higheraltitudes and notable local acceleration especially if the wind character of the
region is bi-directional ~20 per cent energy increase due to local acceleration
(Stankovic, p 160).
4. This option takes advantage of the higher quality winds at higher altitudes andsubstantial local acceleration even if the wind distribution is the same for all directions
a 25 per cent energy increase over a free-standing equivalent can be achieved with an
increase of 40 per cent for bi-directional winds. Although this option requires a loss of
lettable space there are a number of examples of large/tall buildings replacing lettable
area with a feature opening e.g. for aesthetics, sky gardens or to relieve wind loading.
In this case a feature opening can be used to generate wind energy (Stankovic, p160).
5. This is similar to the square concentrator with the exception that the shape lendsitself to HAWT and energy yields are further increased for example for a uniform wind
a 35 per cent energy increase over a free-standing equivalent can be achieved with an
increase of 50 per cent for bi-directional winds (Stankovic p160).
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6. This option takes some advantage of the higher quality winds at higheraltitudes. However, unless the building form is optimized for the local wind
character it is likely that the turbines will not perform as well as free-standing
equivalents (around 8090 per cent of the total energy) (Stankovic, p 160).
7. A range of architectural forms are possible when a multi buildingdevelopment is being considered. Significant local acceleration
can be achieved for reasonably basic, non- optimized forms
around 10 per cent extra energy compared to a free-standing
equivalent (Stankovic, p 160).
Since growing demand on renewable energy in the world, these types
are implemented all over the world by architects and engineers. We will look at two buildings
that implemented all the information we covered in this paper.
Picture 1: Bahrain World Trade Center in Bahrain,completed in 2008, designed by Atkins.
The two 50 story sail shaped office towers taper
to a height of 240m and support three 29m diameter
horizontal-axis wind turbines. The towers are
harmoniously integrated on top of a three story
sculpted podium and basement which accommodates a
new shopping center, restaurants, business center and
car parking. The elliptical plan forms and sail-like
profiles act as aerofoil, funneling the onshore breeze
between them as well as creating a negative pressure
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behind, thus accelerating wind velocity between the two towers. Vertically, the sculpting of the
towers is also a function of airflow dynamics. As they taper upwards, their aerofoil sections
reduce. This effect when combined with the increasing velocity of the onshore breeze at
increasing heights creates a near equal regime of wind velocity on each of the three turbines.
Understanding and utilizing this phenomenon has been one of the key factors that has allowed
the practical integration of wind turbine generators in a commercial building design. (Killa, p2)
Picture 2: Pearl River Tower, in Guangzhou, China, completed in 2012, designed by
SOM.
The initial design concept was to develop a super-tall building
capable of having a net-zero annual energy impact on the city with a
view to being the most energy efficient super-tall building in the
world. The brief for the Pearl River Tower developed into a 71-story,
310m tall office tower with associated a conference facilities, a total
gross area of approximately 2.2 million square feet (Frechette, p 3).
Design process took into consideration the interaction of the
whole building structure and systems and its site location. The key to
a successful high performance requires the design team to consider the
site, energy sources both active and passive, materials, indoor air
quality, and how they might become incorporated into building form
that is more than gestural. These considerations include simple concepts including site analysis,
building orientation, wind direction, sun path analysis to more sophisticated approaches and
technologies including the use of radiant ceilings, double wall systems, photo-voltaic and wind
turbine technology (Frechette, p 8).
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The building incorporates four large openings, approximately 3x4 meters wide. The
facades are shaped to decrease the drag forces and optimize the wind velocity passing through
the four openings. These openings function as pressure relief valves for the building. This
strategy maximizes the wind power potential at these four locations as the power potential from
the wind speed is a cube function of wind velocity, therefore a small increase in velocity can
translate to larger increase in power potential (Frechette, p 8).
The Pearl River Tower will implement vertical axis turbines, as they are capable of
harnessing wind from both prevailing wind direction with mirror efficiency loss. The building
design capitalizes the pressure difference between the windward and leeward side of the building
and will facilitate air flow through the four openings located adjacent to the mechanical floors
within the building. At the windward side there is a stagnation condition that causes the locally
increased pressure to be higher than the undisturbed pressure approaching the building. At the
leeward side of the building a low pressure exists that is induced by the high velocity flow at the
sides and roof of the building (Frechette, p 8).
There are other examples we see in news, however we dont have technical information
on them. We cannot accept them as source. I will express them according to websites
information to show wind turbine installation.
Pictures 3: Starda Tower in London
At 147 metres, the newly opened Strata is
London's tallest residential building. The
turbine with nine-meter blades integrated. If the
turbines work as planned, they should generate
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8% of this 43-storey building's energy needs. This is roughly enough to run its electrical and
mechanical services (including three express lifts and automated window-cleaning rigs) as well
as the lighting, heating and ventilation of its public spaces, which include an underground car
and cycle park.
Source:http://www.guardian.co.uk/artanddesign/2010/jul/18/strata-tower-london-green-
architecture ( Glancey,Jonathan. Sunday 18 July 2010) (April 2013)
Picture 4: Gullwing Twin Wind Tower in Dubai.
Architects and designers at ARXX
Studio have designed a self-sustaining
twin tower skyscraper for Dubai, which
generates all the energy it needs from
renewable sources. Christened the
Gullwing Twin Wind Towers, the tower
incorporates a unique energy generating
system that uses wind turbine hinges
attached to the building to generate electricity from wind. The wings are circular structure, which
drive turbines to produce clean electricity. The turbines are cylindrical with circular sections,
where each section contains a series of bladed rings to
capture the wind. The towers have been designed in the
form of cylinders to simulate a tornado effect to
maximize energy generation. Source:
http://www.greencleaningideas.com/2010/08/gullwing-
twin-wind-tower-skyscraper-is-wrapped-with-wind-turbines/(April, 2013)
http://www.guardian.co.uk/artanddesign/2010/jul/18/strata-tower-london-green-architecturehttp://www.guardian.co.uk/artanddesign/2010/jul/18/strata-tower-london-green-architecturehttp://www.guardian.co.uk/artanddesign/2010/jul/18/strata-tower-london-green-architecturehttp://www.greencleaningideas.com/2010/08/gullwing-twin-wind-tower-skyscraper-is-wrapped-with-wind-turbines/http://www.greencleaningideas.com/2010/08/gullwing-twin-wind-tower-skyscraper-is-wrapped-with-wind-turbines/http://www.greencleaningideas.com/2010/08/gullwing-twin-wind-tower-skyscraper-is-wrapped-with-wind-turbines/http://www.greencleaningideas.com/2010/08/gullwing-twin-wind-tower-skyscraper-is-wrapped-with-wind-turbines/http://www.guardian.co.uk/artanddesign/2010/jul/18/strata-tower-london-green-architecturehttp://www.guardian.co.uk/artanddesign/2010/jul/18/strata-tower-london-green-architecture -
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Picture 5: 525 Golden Gate, in San Francisco CA
525 Golden Gate in comparison to similarly-sized
office buildings features 50% less of a carbon footprint, uses
32% less energy, and consumes 60% less water. The 13-
level, 277,511 gross-square-foot, $190 million SFPUC
headquarters building is one of the greenest urban office
buildings of its kind, bringing together in a modern,
contextually-designed office tower some of the most
innovative new technologies at the forefront of building
design.
A wind turbine tower on the north facade, solar panels on sunny exteriors, sun-shading
and other techniques combine to make the building power-efficient, using 32% less energy than
similarly-sized office buildings. The integrated, hybrid solar array and wind turbine installation
can generate up to 227,000 kilowatt hours per year or 7% of the buildings energy needs. Source:
http://questpointsolarsolutions.com/?tag=wind-turbines (April, 2013)
Environmental affects: Wind energy is one of the cleanest and most environmentally
neutral energy sources in the world today. Compared to conventional fossil fuel energy sources,
wind energy generation does not degrade the quality of our air and water and can make important
contributions to reducing climate-change effects and meeting national energy security goals. In
addition, it avoids environmental effects from the mining, drilling, and hazardous waste storage
associated with using fossil fuels. Wind energy offers many ecosystem benefits, especially as
compared to other forms of electricity production. Wind energy production can also, however,
negatively affect wildlife habitat and individual species, and measures to mitigate prospective
http://questpointsolarsolutions.com/?tag=wind-turbineshttp://questpointsolarsolutions.com/?tag=wind-turbines -
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impacts may be required. As with all responsible industrial development, wind power facilities
need to adhere to high standards for environmental protection. (U.S. DOE) Environmental
concerns associated with wind energy development are noise, visual impact, oscillating shadow,
avian/bat mortality and other concerns.
Noise: Like all mechanical systems, wind turbines produce some noise when they
operate. Most of the turbine noise is masked by the sound of the wind itself, and the turbines run
only when the wind blows. In recent years, engineers have made design changes to reduce the
noise from wind turbines. Early model turbines are generally noisier than most new and larger
models. As wind turbines have become more efficient, more of the wind is converted into
rotational torque and less into acoustic noise. Additionally, proper siting and insulating materials
can be used to minimize noise impacts. (1)Besides noise in the audible frequenciesso-called
infra-noise has also been the subject of concern.(Stiebler, p 7)
Oscillating shadow: The oscillating shadow of a WES (Wind Energy Solutions) due to
the rotating blades optical can also be a source of optical disturbance for residents (disco
effect). Depending on local conditions, minimum distances are required, e.g. 6 times the overall
height as mandated by a court. (Stiebler, p 7)
Visual Impacts: Because they must generally be sited in exposed places, wind turbines
are often highly visible; however, being visible is not necessarily the same as being intrusive.
Aesthetic issues are by their nature highly subjective. Proper siting decisions can help to avoid
any aesthetic impacts.
Avian/Bat Mortality: Bird and bat deaths are one of the most controversial biological
issues related to wind turbines. The deaths of birds and bats at wind farm sites have raised
concerns by fish and wildlife agencies and conservation groups. On the other hand, several large
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wind facilities have operated for years with only minor impacts on these animals. To try to
address this issue, the wind industry and government agencies have sponsored research into
collisions, relevant bird and bat behavior, mitigation measures, and appropriate study design
protocols. In addition, project developers are required to collect data through monitoring efforts
at existing and proposed wind energy sites. Careful site selection is needed to minimize fatalities
and in some cases additional research may be needed to address bird and bat impact issues.
While structures such as smokestacks, lighthouses, tall buildings, and radio and television towers
have also been associated with bird and bat kills, bird and bat mortality is a serious concern for
the wind industry. (Wind Energy Development Programmatic EIS )
Other Concerns: Unlike most other generation technologies, wind turbines do not use
combustion to generate electricity, and hence don't produce air emissions. The only potentially
toxic or hazardous materials are relatively small amounts of lubricating oils and hydraulic and
insulating fluids. Therefore, contamination of surface or ground water or soils is highly unlikely.
The primary health and safety considerations are related to blade movement and the presence of
industrial equipment in areas potentially accessible to the public. An additional concern
associated with wind turbines is potential interference with radar and telecommunication
facilities. And like all electrical generating facilities, wind generators produce electric and
generating facilities, wind generators produce electric and magnetic fields. (Wind Energy
Development Programmatic EIS)
Vibration: Hence, compared to the HAWT, the rotational sampling frequency of a
VAWT is twice as high, because the blades of the VAWT pass the turbulent structures twice:
once at the upwind side of the VAWT and once at the downwind side of the VAWT. Care should
be taken to avoid frequencies of the HAWT or VAWT close to the eigenfrequencies (resonance
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frequency of a system) of the support structure (building roof, building walls, mast, etc.) on
which they are mounted (Merten, p 9).
Shadow flicker: Situations where the wind turbines blades are within the direct path of
the sunrays to the eyes or reflections of the suns rays on the wind turbine blades should be
avoided. The latter is simple to solve with dull paint. Situations where the blades are within the
direct path of the suns rays are a nuisance if the observer is close to the wind turbine and at
visible frequencies below some 20 Hz. Compared to the Darrieus, HAWTs have more problems
in avoiding those low frequencies because of the single-blade passage where the Darrieus has a
double-blade passage between the sunrays and the observer instead. The HAWT is thus more
likely to cause hindrance because of shadow flickering below 20 Hz (Merten, p 10).
Conclusion: We can generate electricity from tall buildings as long as we have enough
information. The first thing we have to do is look at wind availability in macro level. This data
can be obtained from local weather station. If there is enough wind available, we have to
evaluate our site specifically with a professional. In case we have enough wind to generate
power, we should look at the constrains of our site. Which direction wind flows, what blocks it.
We have to orient our building to take advantage of wind while considering wind loads for
structure. Then we have to decide where to install a turbine or turbines. After choosing the right
place for the turbine, we have to accelerate the wind speed with our design. Finally, we have to
keep in mind that even though wind is a clean energy resource, there are some minor
environmental effects that should be considered on designing the buildings.
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ASSOCIATIONS
American Wind Energy Association AWEA
http://www.awea.org/learnabout/
National Renewable Energy Laboratory NREL
http://www.nrel.gov/
The European Wind Energy Association EWEA
http://www.ewea.org/
U.S. Department of Energy DOE
http://www1.eere.energy.gov/wind/small_wind_system_faqs.html
Global Wind Energy Council
http://www.gwec.net/
Citations
Afrin, Shahrina. Green Skyscraper: Integration of Plants into Skyscraper. Stockholm 2009.KTH, Department of Urban Planning and Environment Division of Urban and Regional
Studies Kungliga Tekniska hgskolan. Master Thesis.www.infra.kth.se/sb/sp
Botkin, Daniel B.; Keller, Edward.Environmental Science: Earth as a Living Planet. USA: John
Wiley & Sons, Inc 2011.
Chiras, Dan. Wind PowerBasics. Canada. New Society Publishers 2010.
Eisele, Johann; Kloft, Ellen.HighRise Manuel: Typology and Design, Construction and
Technology.
Fleming, Robins. Wind Stresses in Buildings: With a Chapter on Earthquakes and Earthquake
Resistance. London. Chapman & Hall 1930.
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Frechette, Roger E. Gilchrist, Russell. Towards Zero Energy A Case Study of the Pearl River
Tower, Guangzhou, China. CTBUH (Council on Tall Building and Urban Habitat)Technical Paper. Dubai 2008.http://ctbuh.org/LinkClick.aspx?fileticket=%2bpedN46s7Es%3d&tabid=486&language=en-US/
Johnson, Gary. L. Wind Energy Systems. Manhattan, KS. October 2006
Killa, Shaun. Smith, Richard F.Harnessing Energy in Tall Buildings: Bahrain World Trade
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Muyeen, S.M. Wind Power. Croatia. Intech 2010
Merten, Sander. Wind Energy in the Built Environment: Concentrator Effects of Buildings. UK.
Multi Science 2006.
Stankovic, Sinisa; Campbell, Neil; Harries, Alan. Urban Wind Energy. UK and USA: Earthscan,
2009.
Stiebler, Manfred. Wind Energy Systems for Electric Power Generation. Germany. Springer-
Verlag Berlin Heidelberg 2008
Tong, Wei. Wind Power Generation and Wind Turbine Design. USA and UK: WIT press, 2010
Thomas, Derek.Architecture and the Urban Environment; A Vision for the New Age.
Carbon Trust,A Natural Choice Natural Ventilation.http://www.carbontrust.com/media/81365/ctg048-a-natural-choice-natural-
ventilation.pdf
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CATs (Coherent Application Threads). Wind Turbines. Boston University, Mechanical
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NRCS, U.S. Department of Agriculture Natural Resources Conservation Services.
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Utility-Scale Land-Based 80-Meter Wind Maps
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