DENSIFY
DUBAI Azhar Ahmed Khan
DENSIFY
DUBAI Author Azhar Ahmed Khan Year of Publication 2013 University of Florida Master of Architecture (CORE program) Faculty Advisors Lee-Su Huang Stephen Belton
This project is intended as an exploration of the use of digital technologies as a design tool for the organization of high-density living typologies. The project addresses the changing roles of technology in design from one that aids the designer such as a CAD drawing program that helps a designer perform an otherwise manual task, to ones that involves complex computations that aid in decision making processes, such as optimization programs. Results from these types of computations are often non-intuitive and cannot usually be achieved through conventional means. The new roles that technology plays must be assessed as to their scope and the degree to which their results can be effective.
With over half of the world’s population now residing in urban areas it is essential to develop strategies to address the increasing needs of public transport, energy demands, sanitation and living space. As cities get more populated their options are generally reduced to that of expansion or densification. Expansion offers a tabula rasa landscape upon which many autonomous designs may operate. Densification on the other hand requires one to carefully assess the existing context in order to develop a holistic model that is not only functional in terms of available living space but also in terms of cultural identity and environmental responsibility. This project will attempt to “densify� a city by means of the design of highdensity living spaces rather than expansion. It is important to note that this project is not the development of a design suitable for a single site but rather the development of design strategies that can be implemented on various sites and scales. The city of Dubai has addressed its rapidly expanding population by means of expansion during the past few decades. This expansion is carried out through various development projects
that include expansive single-family development plots to tall multistory mixed-development projects. The result is a landscape of disparate environments showing limited cohesion among themselves and within the city as a whole. By addressing the population through densification we can analyze existing typologies and their attributes. One typology in particular is that of the vernacular. A critical analysis of the vernacular architecture reveals cultural and environmental lessons that have been forgotten over time. By applying such lessons in the design of a new housing typology we can explore the possibility of a contemporary design that responds culturally and environmentally to its context. The project can thus be summarized as an exploration of computation tools in the design of a high-density typology based on the vernacular architecture of Dubai. The book is divided into three parts. First is an introduction to the city of Dubai and a critique of its current condition as an urban city. The second is an analysis of the vernacular architecture. The third is the implementation of the lessons learned from the vernacular in a highdensity typology intervention.
I
THE CONTEXT DUBAI An Overview of Contemporary Issues
The City
The Origins of Bastakiyya
The city of Dubai is one of seven emirates that comprise the nation of the United Arab Emirates (UAE). Founded in 1972 the UAE is a fast growing commercial hub for the Arabian Gulf region that has undergone major change and growth during the past few decades. Dubai, its largest Emirate after the capital Abu Dhabi, has demonstrated the most dramatic growth. The population of the city, a mere 180,000 in 1975 has since increased to 2 million people that comprise over 200 nationalities.1 In fact, less than 10% of the city’s population is indigenous, or ‘Emirati.’
Dubai started as a small coastal town concentrated around a small water inlet (the Dubai Creek) that served as one of the Gulf’s few natural harbors. As such, the city primarily survived on fishing, trade and the pearl diving industry.
Dubai is an ideal candidate for exploring high-density typologies given that the city has chosen a mode of expansion as its primary means of dealing with its increase in population.
1 2 3
An 1822 account of Dubai from an English traveler describes the town as a “miserable assemblage of mud hovels” with dilapidated towers and old rusty guns 2, a stark contrast to what the city is today. From the 1830’s onwards Dubai came to see some prosperity through the tolerance and openness of its rulers to outsiders.3 Towards the end of the century Iranian merchants flocked to Dubai for new opportunities as taxes had been raised in their home nation under the Shah of Iran. These merchants were primarily from the Bastak region and settled in Dubai to form one of the city’s oldest communities, Bastakiyya, parts of which still exist today and offer us a glimpse into the local Persian-inspired vernacular architecture of the region.
Yasser Elsheshtawy, Dubai: Behind an Urban Spectacle (London: Routledge, 2010), 1. Elsheshtawy, Dubai, 60. ibid, 64.
Google Earth image of the city: the creek, Palm Islands and World projects are clearly visible.
Aerial photograph of Bastakiyya district in 1978. One can clearly identify closely packed houses, courtyards, and windtowers.
Contemporary Issues Facing Dubai This pace of growth, however, has brought about several challenges for the city in the realms of cultural identity, environmental responsibility and planning strategies. John Harris, a British architect, can be considered the first Western architect who holistically considered the environmental and cultural factors of the city when he designed the city’s first master plan in 1960 as well as designing the city’s first skyscraper, the World Trade Center (which at 40-storeys was the tallest building in the Arab world). Since then Dubai the vision for the city has shifted, and international architecture firms with limited experience and knowledge of the climate and culture of the region have been recruited to fulfill this vision. The result has been a diverse range of eclectic icons for the city where each project aspires to beat the last. Western architects, attracted to the opportunity of designing in a non-contextual environment, have turned Dubai into a mega-scale experiment where anything is possible. Dubai now boasts some of the world’s most expensive hotels, some of the biggest malls, the world’s tallest tower and artificial islands. These projects are mostly controlled by developers focusing on large scale mixed-used developments as well as expansive ‘suburban’ housing developments. These planned communities generally consist of dozens of houses with little access to public spaces and amenities.
The 1960 master plan for Dubai by John Harris. The plan expands outwards from Bastakiyya. The new city is seen as an extension of the existing city utilizing existing roadways and maintaining a close proximity to the creek. 1960
2003
The newer, expansive structural plan adopted by the city in 2003 is drastically different. It chooses to expand along the coast and consists of multiple pockets of high density areas connected by highways. The spaces in-between are generally filled with ‘suburban’ housing.
Planning Issues One of the drawbacks of developing suburban neighborhoods to address a growing population is to successfully integrate them with services such as grocery stores, public transport and civic buildings. The historic district of Bastakiyya demonstrates that residents were within walking distance from each other, as well as the mosque, the souk and other services.
Karama, developed in the 1970s and 1980s, is considered the most dense residential neighborhood in Dubai and provides its residents with a park, a shopping mall, restaurants, grocery stores, two mosques and plenty of retail stores. Karama also maintains a close proximity to the creek and is close to some of the older parts of the city. Jumeira Islands, developed in the 2000s was designed as an autonomous neighborhood far from the original city. This gated development provides little to no services for its residents.
Jumeira Islands, a gated housing development towards the western end of the city, offers its residents luxury houses on a group of ‘islands’. This isolation, however, distances the residents from basic services.
Public Space Grocery/Retail Civic/Religious Public Transport
The Karama district primarily consists of mid to low-rise residential apartment buildings. This highly dense neighborhood offers its residents plenty of services within walking distance.
The Bastakiyya district also offered its residents public spaces, a mosque and other services within walking distance.
Cultural Issues The nature of Dubai’s architecture results in a built environment that fails to convey any form of cultural identity for the city. Rashad Bukash, head of the Department of Historic Preservation at the Dubai Municipality comments that “Identity is something that is unfortunately lacking in Dubai… the worst type of feeling is that you are a stranger in your own country. We need to create an identity for Dubai that is related to Arab heritage.” 4 Dubai’s vernacular architecture is perhaps the only remaining expression of the city’s culture and also the only source of authentic architecture left. The area of Bastakiyya is home to the surviving vernacular coral-stone houses, most of which had been demolished in the 1970s and 1980s ,5 which have now been renovated to support art galleries, museums and cafes.. Removed from their social context and primary purpose as a residential neighborhood has reduced them to mere “fossilized version” of a once “vibrant district”. 6
Elsheshtawy, Dubai, 96. Ronald Hawker, “Where’s the air conditioning switch; identifying problems for sustaining local architectural traditions in the contemporary United Arab Emirates” (paper presented at the 2nd International Conference on Urban Regeneration and Sustainability, Sergovia, Spain, 2002). 6 Elsheshtawy, Dubai, 81. 4 5
The Bastakiyya district today, a ‘shell’ of the past.
A traditional house repurposed as an art gallery.
Accepted Norms The issue here is not only that there is a lack of architecture that addresses Arab culture but that the iconic architecture in Dubai, such as the Burj al Arab hotel and the Palm Islands are considered as accepted forms for representing “national self-image” to the point that the Burj al Arab adorns Dubai’s license plates. Vernacular architecture has little to do with the modern Emirati narrative. There is the perception that “no practical lessons can be gleaned from vernacular traditions for the architecture of the present”7 and the notion of equating ‘poverty with the past.’ 8 Arab families have left behind their homes of mud and coral-stone to those of concrete, marble and glass and windtowers have been replaced by mechanical airconditioning. Foreign dominance of media and education has further added to this identity crisis in a city where 9 out of 10 people are expatriates. Emiratis,
One of the country’s oldest windtowers juxtaposed with imitation towers on top of a high-rise building.
8 9
Hawker, “Where’s the air conditioning.” ibid.
wishing to leave their ‘impoverished’ past behind them are finding it difficult to find a suitable form of architecture that best represents their current state while respecting their heritage. The purpose of vernacular in Dubai today is limited to that of symbolism. Non-functioning windtowers and vernacular motifs can be seen around the city as means of connecting with the past. There is an entire hotel and shopping mall designed to mimic a traditional souk that is complete with its own canals and windtowers. The issue here is that an architectural element as strong as the windtower whose form and materials were derived from pure functional and regional factors has been reduced to a decorative construct whose sole purpose it to evoke some sort of nostalgic memory for the city; an example of heritage being replaced with “staged and packaged environments.”9
Imitation windtowers scattered across the ‘packaged environment’ of the Madinet Jumeira Mall and Hotel.
The Dubai creek where one can observe artificial windtowers mimic the authentic ones.
Environmental Issues The United Arab Emirates is among one of the highest consumers of energy on the planet. This can be contributed to several factors such as the heat island effect, water usage and the high demand for mechanical air-conditioning. Motor vehicles contribute to over 80% of pollution levels.10 Air-conditioning units, particularly those in the city’s more densely populated areas, produce large amounts of heat that remain trapped in the streets and alleyways between buildings. This trapped heat has little means of escaping and transfers back into building interiors where it is cooled again, thus producing more heat. Most building’s in Dubai, particularly the city’s skyscrapers, pay little attention to solar and wind patterns of the region. Solid towers clad in glass curtain walls fail to shade areas that are exposed to strong solar insolation. In addition, most buildings also treat the wind as an obstacle rather than a potential cooling element. Furthermore, most materials for construction such as steel are imported into the country and little use is made of existing local resources. 10
Elsheshtawy, Dubai, 120.
80
CO2 emissions per capita
70 60 UAE
50 40 30 20
North America
10 0
Europe & Central Asia
Middle East & North Africa 1972
1976
1980
1984
1988
1992
1996
2000
2004
2008
Electricity consumption per capita 14,000 12,000 North America
10,000
UAE
8,000 6,000
Europe & Central Asia
4,000 2,000 0 1960
Middle East & North Africa 1966
1972
1978
1984
1990
1996
2002
2008
Energy use per capita 12,000 UAE
10,000 8,000
North America
6,000 4,000
Europe & Central Asia
2,000 0 1950
Middle East & North Africa 1970
1980
1990
2000
2010
I
THE ANALYSIS BASTAKIYYA Lessons from Vernacular Architecture
Perhaps answers to some of these problems can be found in the vernacular architecture of Dubai. Although the investigation of the subject matter is restricted to the time period and available materials and technologies of the early 20th century, there may still be valuable lessons to be drawn that can still be applied today. For the scope of this project, two specific questions are asked: 1. How does the vernacular architecture of Dubai respond to the culture of the region?
2. How does the vernacular architecture of Dubai respond to the climate of the region? Between 1969 and 1974, architect Peter Jackson and social geographer Anne Coles surveyed and documented the Bastakiyya area. Their drawings, photographs and observations into the everyday lives and architecture of the indigenous people offer us a unique insight into the social context that is currently absent from Bastakiyya.
Urban Form and Culture The strongest influence on Arab culture in Dubai is guided by the religion of Islam followed by Bedouin traditions. Islamic tradition emphasizes the importance of the family unit and its relation to the larger community. As such the urban form is such that it generates a “high degree of active social interaction and strong neighborly relationships.�11 Thus the religion favors urbanization12 , houses in close proximity to each other with opportunities for greeting and meeting others. In addition, modesty is encouraged and social discrimination discouraged. This attribute is expressed in the facades of the homes at Bastakiyya that display little or no ornament at all except for at the entrances. 13 Embellishments and expressions of wealth are usually displayed on the interiors of houses. To maintain a sense of social cohesion, communities were usually only big enough such that all members were within walking distance from one another. 14 Anne Coles and Peter Jackson, Windtower (London: Stacey International, 2009), 28. 12 ibid, 29. 13 ibid, 38. 14 ibid, 30. 11
A 1950 map of the city shows its organic layout and cellular nature of expansion
A 1974 aerial photo of Dubai showing the relationship between the Bastakiyya district and the creek
The Windtower The windtower is a passive-cooling structure that rises above the roof of a house at between 12m to 15m above ground level.15 The purpose of the windtower is to harness breezes and direct them down into the room or basement below and offers a method of passive-cooling in a region where temperatures are generally high all year round. The use of windtowers can be dated back three and a half thousand years, as evident in paintings of the ancient Egyptians.16 They are still widely used today as a passive cooling device and several fine examples can be found in regions of Iran, India and the Arabian Gulf.17 Dubai’s windtowers are a direct descendant of those that are from the Bastak region in Iran whose artisans and masons brought the skills over during their migration. Towers are typically constructed of areesh (palm fronds) and later ‘upgraded’ to masonry towers made from coral stone and mud plaster. Within the walls of the tower are X-shaped vanes that direct the air from the tower opening above the roof to the rooms below. The X shape of the vanes allows the tower to capture breezes from any direction. There are towers with as many as eight vanes. Increasing the number of vanes allows the towers to increase the effective area that faces the wind, thus minimizing the reduction of speed of the incoming wind as it makes contact with the vanes. The drawback, however, is that the effective volume is reduced and so designers will need to compromise on one of them.18 Coles and Jackson, Windtower, 166. Susan Roaf, “The Windcatchers of the Middle East” (paper presented at a symposium organized by the College of Architecture and Planning, King Faisal University, Dammam, Kingdom of Saudi Arabia, January 5-10, 1980). 17 ibid 18 ibid 15 16
A section of the windtower reveals the vanes that allow the tower to capture air from any direction. The number of vanes can vary. The more vanes that a tower has, the more adapted it is to shifting wind conditions, however, this also reduces the overall volumes of the air that may enter the tower.
Typical operation of a windtower 1. Cool air enters the tower through the opening at the top and is drawn into the interior spaces below via the vanes 2. The air not only ventilates the stale air in the space but also improves comfort through evaporative cooling.
1
3. Negative pressure outside the tower pulls the air back out.
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+ + +
-
3
Windtower Orientation Windtowers in Dubai are generally oriented to the North-South direction. This particular orientation allows for optimum exposure to the cool afternoon sea breezes that arrive from the NorthWest.19 In this orientation, the vanes within the tower are parallel to the prevailing winds and this allows for the maximum volume of air to be directed down into the room below.
The average angle that a windtower is oriented is around 62 degrees from its diagonal to the east-west axis
Windtower Proximity A windtower is only effective when it optimizes its exposure to incoming breezes. Thus any breezes that experience turbulence from contact with other towers and structures will not be as effective for subsequent towers. Thus towers need to ensure that they maintain certain distances from other towers such that they receive unobstructed air and that they do not obstruct the for other towers in their vicinity.
An optimum distance can be determined for use in future tower design
19
Coles and Jackson, Windtower, 167.
Windtower
Diagram showing the relative orientations of the windtowers in Bastakiyya. Towers are arranged so that their diagonal axis faces incoming breezes.
Diagram showing minimum distances from each tower to the next
Windtower Placement Masonry wind towers are heavy and their load is generally carried through the masonry walls down to the foundations.20 Therefore, towers are generally placed where masonry walls meet at corners or at other locations along a wall. Generally one of two things happens; either the orientation of the wall will dictate the direction of the tower or the placement of the tower will dictate the direction of the walls. In either case it is interesting to note that in many occasions this has an effect on the plan of the building as well as the streets adjacent to them. Orthogonal plans are at time ‘bent’ to accommodate a windtower. 20
Diagram showing windtower location and affected load-bearing walls.
Coles and Jackson, Windtower, 166.
Windtower Load Bearing Wall
Additional Wind Strategies Windscoops are another passive-cooling technology employed by Bastakiyya houses. They are generally recesses in the outer walls that allows for passing air to be directed to floor of the interior rooms. In interior rooms this helps cool inhabitants that sit on the floor and coupled with the effects of the windtower can provide a more comfortable environment. On the roof, parapets are designed to serve as windscoops such that the air passing over the roof carries heat from the surface via convection and mitigates the transfer of that heat to the rooms below.
Drawing of a wall section of the Bukash house showing wind scoops on the upper floor and roof.
Windscoops were also used to cool water stores and wells
The Courtyard The courtyard house form is the most common housing typology in the Bastakiyya area. Generally, the courtyard serves as private outdoor space for the family and encompassed with three ‘tiers’ of parallel spaces: verandas, inner rooms, and outer rooms.21 The courtyard serves as an organizing element for each home as main summer living spaces are generally placed on the south of the courtyard, winter living to the north, and multi-purpose spaces to the east and west. 22 The courtyard is also seen as a symbol of paradise in Islam.23 In the harsh desert environment, the private garden serves as a sanctuary and a place of rest. Families usually plant a garden with at least one tree in their courtyard. The tree provides shade and the cooler air underneath is kept trapped in the courtyard by the surrounding spaces creating a relatively comfortable microclimate. Climatically the courtyard can also assist in air circulation of the surrounding rooms, specifically the windtower rooms. Air circulation around the rooms can be adjusted via doors and windows that open onto the courtyard; when open, air circulation inside the rooms is better and some air vents out through the courtyard; when closed, the circulation within rooms is strong but it limited to the area directly under the windtower.24 Coles and Jackson, Windtower, 26. ibid, 39. ibid, 32. 24 ibid, 70. 21
22 23
A typical courtyard showing inward facing windows and verandas
A courtyard with an interior garden and movable furniture
Courtyard Orientation Generally, courtyards tend to be oriented along the east-west axis. This reduces their exposure to the sun when it lies on the east and west but increases the exposure on the northern face of the courtyard from the summer sun.25 This is acceptable as even though the southern sun is stronger its penetration is limited by its high azimuth as opposed to the lower sun on the east and west.
25
Coles and Jackson, Windtower, 39.
Veranda Orientation Verandas are generally placed on the southern end of the courtyards as that ensures that they are always shaded. Verandas are sometimes found on all four sides of the courtyards and this mainly depends on the available space that the plot has to offer. Verandas not only serve as an interstitial indoor-outdoor space but also serve as an interstitial semi-private space between the individual family and the collective family of the house.
Courtyard Major Axis
Diagram showing courtyards with their major axes in the east-west direction
South Facing Veranda Other Verandas
Diagram showing the location of verandas with respect to courtyards.
The Majlis Orientation Arab culture imparts a strong emphasis on privacy between private and public life as well as between men and women.26 Thus the sequence of spaces that lead from the public exterior of the building to the private interior are specifically designed to limit views and accessibility. One of these spaces is the majlis. The majlis is a room in the house that programmatically serves as a space for entertaining guests. This space is accessed through a lobby space and is generally placed in one of the corners of the house.
The walls of most houses are solid on the first level with limited openings on upper levels. One reason is to ensure privacy of the inhabitants from the street. Another reason is to exhibit a modest faรงade that tries not to distinguish itself from ones on other houses. An exception to this solid nature of the walls is that at the majlis where one can find large windows that can optionally be closed with shutters. The visual connections with the street allow passersby to hear, smell and see the activities within the majlis. 26 27
Coles and Jackson, Windtower, 31. ibid, 37.
Majlis
In the Bastakiyya area the majlis are generally located along streets that funnel the cool afternoon breezes.27 As such most majlis can be found either facing north-west or facing a street that carries the north-westerly winds.
Interior of Majlis showing tall room height and large windows
Streets Streets in the Bastakiyya were only as wide as they needed to be. Generally between 6’ to 12’ in width, streets were generally wide enough to allow two people to walk side by side or for two donkeys and carts.28 The restricted widths of the streets served several purposes. 1. The streets acted as funnels for breezes.29 Streets orientations were similar to windtowers orientations in that they aligned with the cool afternoon breezes. Their narrow widths forced winds to travel faster between them (Venturi effect). 2. By maintaining a narrow section streets were shaded for most of the day by the surrounding buildings. Buildings thus also shaded each other. In fact, on the summer solstice, a narrow street (5’ wide) would only be exposed to direct sunlight for a little over an hour and a wide street (15’ wide) would only be exposed for three and a half hours. Streets were always offset from each other even as they followed the same axis. This is primarily to reduce the distance that any line of sight travels within a street. Narrow lanes between houses were considered as semi-public spaces for the inhabitants within which women and other family members could freely move about. The private nature of these streets was maintained by limiting their length and lines of sight into them from surrounding spaces. 28 29
Coles and Jackson, Windtower, 31. ibid, 37
Narrow lanes ensure that the total solar insolation falling on the street surface is minimized (5 ft and 15 ft wide streets shown)
Close proximity of houses ensures that one house can shade the other as well as the street between them
Digital model demonstrating the deeply shaded streets in the district
The colored areas represent interior streets with restricted views from larger public areas. Even within these spaces sight lines are further restricted through shifts in the street’s otherwise linear direction.
Diagram showing typical street widths in the district
Facade Studies: The Bukash House The vernacular architecture in Bastakiyya is a direct result of both cultural and environmental factors. At times, designers had to make decisions on which factor was more important. This is clearly illustrated in the case of the Bukash house where program placement and façade openings do not correspond with intuitive design methods. North Façade The Bukash House has an east-west orientation and thus the north façade lies along the house’s longer axis. One would expect to see large opening to let in the evenly lit northern light but in contrast this façade has the least number of openings. Large openings are only seen at the north-western upper floor where there is a windtower room. South Façade The Bukash House has no neighbors to its south as it faces an open public space. As such there is no shading on this facade of the house. This is primarily because at this position the majlis not only receives cool air that is funneled through the adjacent street but that it also faces one of the community’s public spaces. Since the majlis is always directly next to the entrance this also allows for the house’s primary entrance to face this public space.
North Elevation of Bukash House
South Elevation of Bukash House
East Faรงade The Eastern facade takes advantage of being partially shaded by its neighbor and has a fair number of openings that allow indirect light to enter. Large openings can be seen at both windtower rooms that occupy the corners.
West Faรงade The western faรงade is only partially shaded yet has some of the largest openings on the upper floors for a family room. This is counter-intuitive as the strong western sun will penetrate deep into these openings and potentially increase solar heat gain. The family room is situated as such perhaps because it is the only space through which the inhabitants can look down into the majlis below to observe guests from a distance.
The next stage is to apply the vernacular techniques in a contemporary context. Vernacular characteristics defined earlier will be reinterpreted and applied to design a large urban housing intervention.
East Elevation of Bukash House
West Elevation of Bukash House
II
HOUSING INTERVENTION Optimizing Spatial Configuration with Computational Tools
Genetic Algorithms To understand genetic algorithms one can use the biological analogy of a tree. A tree transplanted in an area other than its native environment will need to satisfy several criteria in order to flourish such as height above ground, root depth, leaf shape and leaf distribution, etc. As the trees mate and form new generations the offspring that adapt themselves to their environment will survive while others will perish. These successful offspring will mate again and the cycle will continue until several generations later we achieve a tree that is close to an ‘optimal’ state of equilibrium with its environment. Genetic algorithms work on a similar principle. Computational tools allow designers to optimize designs to meet certain criteria, whose computations by hand would be too laborious. For example, it would almost impossible to adjust all the parameters that go into designing a tower that has 1) maximum southern exposure, 2) fixed square footage, 3) fixed volume and
2
1 DESIGN INTENT
4) minimum surface area. However, computational tools using genetic algorithms will provide us with several models that satisfy all these conditions simultaneously. It must be noted that genetic architecture is neither a form-finding tool nor necessarily a form of biomimicry. It does not mimic forms found in nature. In other words “genetic architecture is neither a representation of biology nor a form of biomimesis”30 , it is merely using genetic ‘techniques’ perfected by nature. It is important to identify the unique nature of this type of computation. So far, computing technology as a tool has been used as an ‘extension of the hand.’ It has allowed us to create accurate drawings, performs calculations, etc. all of which are tasks that could be done manually. Genetic algorithms serve as an ‘extension of the mind’, here the computations produce results that cannot be achieved by physical calculations alone.31
3 PROBLEM SETUP
DEFINE PARAMETERS
4 RUN OPTIMIZATION
6 REORGANIZE PROBLEMs
OPTIMIZATION PROCESS Erik Ghenoiu, The view from the cloisters Karl Chu, Metaphysics of Genetic Architecture and Computation 30 31
1. DESIGN INTENT This specifies the purpose of using the optimization sequence as opposed to a conventional means of obtaining an intuitive solution. 2.
3.
4.
PROBLEM SETUP An outline of how the problem will be setup for the program to operate on is laid out. Initial attempts at this setup will generally produce undesirable results and the setup will have to be tweaked often to achieve favorable results. DEFINE PARAMETERS At this stage we define the variables and fitness values. The variables are parameters that the program is allowed to change to affect physical elements in the model. The fitness values are specific parameters that we wish to minimize or maximize. RUN OPTIMIZATION Once the problem and parameters are setup we run the optimization program for a predetermined number of ‘generations’. The number of generations are generally determined through a series of test runs. The higher
the number of generations the more accurate the results, however, this increases the processing time that is needed. 5.
INVESTIGATE RESULTS At this stage we examine the validity of the optimization results. The given solutions, although optimized for their respective parameters, may not meet our design needs with respect to factors such as scale, diversity and aesthetics.
6.
REORGANIZE PROBLEMS If needed, the problem and parameters may need to be modified.
7. IDENTIFY POTENTIAL DESIGN SOLUTIONS Once a favorable optimization sequence is completed we need to critique our results to narrow down our selections. 8.
EDIT The last stage involves a series of changes that need to be made to the optimized result. Intervention of the designer at this stage to correct any issues demonstrates the limits to which the program is successful.
Mediating computer solutions
5
7 INVESTIGATE RESULTS
IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
For the purpose of this research project we shall employ computational tools as an integral part of the design process. 3D modelling tools, parametric design tools and evolutionary solvers will be used to set-up complex problems whose variables are derived from the Dubai vernacular. In order to mediate the influence of computational solutions it is important to criticize them with an architectural frame of reference. Thus, at each stage in the design process there are moments where we analyze results and pick out those that seem ‘to make sense’ rather than those that are the most computationally optimum. The flowchart to the left summarizes the design process.
STEP 1: Establishing a Target Density The first step in designing the high-density development is to recognize the scope of our intervention. By examining city plans and population statistics it is possible to break the city down into 4 housing typologies: 1: Low-Rise Housing 2: Single Family Housing 3: Mid-Rise Housing 4: High-Rise Housing
1950s-1980s 1890s-present 1980s-present 1990s-present
A digital model of the city displaying housing typologies with respect to population densities. We can use this mode to compare typology adjacencies as well as spatial relationships between districts.
Population Density (people/hectare)
By observation we see that most families are concentrated near the creek where densities range from 40 people/hectare to over 180 people per hectare. For the thesis project we set a goal of 130 people/hectare. Family Density (people/hectare)
STEP 2: Modeling Strategy
Building Units The goal of this project is to challenge existing housing typologies by introducing a new typology that is derived from the Dubai vernacular, thus accounting for cultural and environmental constraints. In order to achieve this we will utilize the courtyard house as basic flexible units that be used in a multi-storey scenario.
Windtowers In addition, we will reinterpret the vernacular form and role of the classic windtower. Traditionally, windtowers have solely affected interior volumes. To expand their role in the urban environment we will utilize windtowers as a passive cooling strategy for both interior and exterior spaces allowing for streets and plazas to be cooled as well.
Vernacular typology
Current typology
Hybrid typology
Optimized hybrid typology
Traditional Setup Windtower cooling interior spaces
New Setup Windtower cooling interior and exterior spaces
STEP 3: Site Selection The chosen site upon which to implement the strategy is an empty plot that is adjacent to the Dubai creek, the historic Bastakiyya district and high-density midrise housing. The plot is a graveyard and it is unlikely that there will ever be any construction on this site. However, it has a scale that can accomodate several blocks. In addition, its adjacency to the historic district and mid-rise housing allow us to compare our results with existing scales on the site. The site is open to the creek and so we can assume an uninterrupted flow of fresh air from the North-West.
The site is divided into five smaller ‘blocks’ by streets that will establish connections accross the site.
Public park
Bastakiyya
Creek
High-density mid-rise housing
Connecting to neighboring streets
Bus stop
connection to public park
Step 4: Nature of the Vernacular Grid The Bastakiyya historic district follows a rectilinear grid that is stretched and skewed at various locations. Upon examination it is clear that each of the building units take on one of two modes: either they are standalone or they cluster together to form a group of buildings.
Plan of Bastakiyya showing underlying grid lines
Aside from geographic constraints, wind plays an important part in the form of the Bastakiyya grid. Streets, particularly those that run North-South, are oriented so as to maximize their exposure to incoming cool afternoon breezes from the NorthWest. The wind passes through streets and plazas to help create comfortable outdoor environments.
Plan of historic district showing wind penetration through streets and public spaces.
Original 100’X100 grid
Grid distorted with attractor points
Calculate angle of outer streets with respect to wind
1 DESIGN INTENT
Our first step is to establish a base grid on our site. In order for our grid to relate to the vernacular we will attempt to optimize it for wind and for shortest paths across the site. We will use the optimization template outlined earlier.
1. DESIGN INTENT - To obtain an optimized grid configuration where the streets are aligned to the direction of the wind. 2. PROBLEM SETUP - An orthogonal grid is distorted by a number of attractor points. For each configuration, the angle between the outer streets and the direction of the wind is calculated. We can also calculate the length of the paths that run across the site. We also remove cells with the smallest areas and those with a N-S orientation and replace them with public space.
OPTIMIZATION PROCESS
Step 5: Grid Optimization
2 PROBLEM SETUP
3 DEFINE PARAMETERS
4
6 RUN OPTIMIZATION
REORGANIZE PROBLEM
5 INVESTIGATE RESULTS
7 IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
Eliminate cells with N-S oriented aspect ratios
Eliminate cells that are lower than a predetermined minimum area
Shortest paths across grid
3. DEFINE PARAMETERS
1 DESIGN INTENT
Variables: 1. The number of attractor points
Fitness: 1. Given that the wind in Dubai is fairly consistent we can calculate the angle between each street with respect to that general wind vector. The average angles of all the ‘bordering’ streets with respect to the wind become our first fitness value. In order to maximize wind penetration we wish to MINIMIZE this fitness value. 2. As discussed earlier we have established points of interest and connections across the site that we wish the grid to accommodate. We can calculate the shortest paths across the grid for each iteration. These lengths become our second fitness value which we also wish to MINIMIZE.
OPTIMIZATION PROCESS
2. The location of each attractor point on the grid.
2 PROBLEM SETUP
3 DEFINE PARAMETERS
4
6 RUN OPTIMIZATION
REORGANIZE PROBLEM
5 INVESTIGATE RESULTS
4. RUN OPTIMIZATION 5. INVESTIGATE RESULTS 6. REORGANIZE PROBLEMS Initial adjustments included adjusting the size of the grid. Other adjustments needed to be made regarding the depth of the outer streets that are to be examined as well as limiting the range of the number of attractor points.
7 IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
1 DESIGN INTENT
OPTIMIZATION PROCESS
2 PROBLEM SETUP 7. IDENTIFY POTENTIAL DESIGN SOLUTIONS The top 16 solutions were analyzed. Aside from the fitness parameters, additional factors needed to be considered such as: 1. availability of public space 2. diversity in cell areas
3 DEFINE PARAMETERS
4 RUN OPTIMIZATION
3. location and nature of oblong and oddly shaped cells 4. vehicular road access from blocks
6 REORGANIZE PROBLEM
5
5. linear trajectory of roads
INVESTIGATE RESULTS
6. shifting residential streets to limit sight lines
7 IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
It is important to note that the selected result may not be the most optimum computationally but can still satisfy a majority of evaluation factors.
The grid is converted to the lower plan of the development with major vehicular avenues, public spaces and courtyards determined
Further analysis demonstrates how the streets are effective at ventilating public spaces.
1 DESIGN INTENT
OPTIMIZATION PROCESS
2 PROBLEM SETUP 8. EDIT Once the final solution is picked we further edit it to meet our design needs. Below is the unedited output of our chosen configuration. Several changes were made to convert this layout to one that we can effectively use on our site. 1. With respect to the shortest paths (shown in red) we need to reroute the North-South path on the left to remove the awkward turn at the northwest corner 2. There are several pockets of public space that can be connected together via a public promenade that runs though the site in order connect pedestrians across the site (shown in green).
3 DEFINE PARAMETERS
4
6 RUN OPTIMIZATION
REORGANIZE PROBLEM
5 INVESTIGATE RESULTS
7 IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
Determining the grids: Each successive grid is derived from the center points of the grid underneath. This ensures that there is no direct overlap of cells as well as so that there is some continuity in the general language of the grid from one level to the other.
1 STEP 6: Adding Additional Levels
Light penetration diminishes as we add layers on top of one another. Our goal is then to find an optimum configuration of cells such that we can achieve a high-density of cells along with enough porosity for light to the layers underneath. 1. DESIGN INTENT To obtain two levels of cell configurations that are optimized for light penetration as well as for maximum available living space (maximum density) 2. PROBLEM SETUP At this stage the nature of the cells and grid on level 1 has already been determined. A new grid system is derived from the center points of the level 1 grid to serve as the grid for level 2. In a similar way the grid system for level 3 is derived from that of level 2. The grids are then populated with cells with respect to a variable group of points on the grid and a solar analysis is conducted for each iteration. The process involves creating a courtyard at the center of each cell and then testing the courtyard surfaces for total solar insolation. The total number of cells for each generation is also calculated.
OPTIMIZATION PROCESS
So far we have only optimized the first level. In order to determine the organization of additional layers we could simply run the optimization sequence again with a different set of constraints. Instead we are going to tackle the biggest disadvantage of stacked living areas - loss of light.
DESIGN INTENT
2 PROBLEM SETUP
3 DEFINE PARAMETERS
4
6 RUN OPTIMIZATION
REORGANIZE PROBLEM
5 INVESTIGATE RESULTS
7 IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
Each Grid is then populated with cells. The lowest grid is always fully populated as its cells cannot affect the solar insolation on cells that are above it. Cells on levels 2 and 3 are based on a similar system of attractor points as used in the grid optimization process. Each attractor point ‘attracts’ at least 3 cells such that no one cell is left alone (i.e, there are always at least two neighbors per cell) The goal is to maximize the number of cells while also maximizing the amount of light that passes into the intervention.
1 DESIGN INTENT
2
Variable:
PROBLEM SETUP
OPTIMIZATION PROCESS
3. DEFINE PARAMETERS
1. The number of cells on the grid to populate 2. Grid location of each cell 3. The minimum number of ‘neighbors’ associated with each cell Fitness:
3 DEFINE PARAMETERS
4 RUN OPTIMIZATION
1. Total solar insolation in each ‘courtyard’ (to be maximized) 2. Total number of cells (to be maximized)
6 REORGANIZE PROBLEM
5 INVESTIGATE RESULTS
7 IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
Sample configuration showing housing units in white and ‘test courtyards’ with their respective radiation meshes
The same sample configuration showing only the test courtyards
1 DESIGN INTENT
OPTIMIZATION PROCESS
2 4. RUN OPTIMIZATION Using a simulation program we can determine the amount of light that falls upon each ‘courtyard space’. At each computational iteration the computer calculates the solar exposure as well as the total number of cells.
PROBLEM SETUP
3 DEFINE PARAMETERS
5. INVESTIGATE RESULTS 6. REORGANIZE PROBLEMS For most runs, the size of the courtyards needed to be adjusted. Eventually, the dimensions of each courtyard were a determined with respect to the area of their respective cells. Other modifications were made to ensure that there were no isolated cells; that each cell always had at least two neighbors.
4
6 RUN OPTIMIZATION
REORGANIZE PROBLEM
5 INVESTIGATE RESULTS
7 IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
1 7. IDENTIFY POTENTIAL DESIGN SOLUTIONS
1. Level of porosity over public spaces 2. Ensuring that there were no level 3 cells without any level 2 cells to support them, resulting in ‘hovering’ masses 3. Possibilities for vehicular and pedestrian circulation paths on level 2 and 3
OPTIMIZATION PROCESS
After the optimization program was run the top four ‘fittest’ configuration were critiqued for additional factors:
DESIGN INTENT
2 PROBLEM SETUP
3 DEFINE PARAMETERS
8. EDIT Only a limited amount of editing was needed to adjust for some courtyard dimensions and for some oddly shaped cells.
The top four fittest configurations were tested on the site as physical models. The model shown at the bottom is the one selected as the final configuration
4
6 RUN OPTIMIZATION
REORGANIZE PROBLEM
5 INVESTIGATE RESULTS
7 IDENTIFY POTENTIAL DESIGN SOLUTIONS
8 EDIT
3D rendering of all three levels
STEP 7: Determining Voids: Public Paths Once we have finalized the 3-dimensional configuration of cells the next step is to examine each plan to determine the locations of primary, secondary and tertiary modes of circulation. Vehicular paths and pedestrian streets can only be created if the cells give up some of their area. In essence, it is the void between the cells that is public space. Therefore, it is necessary to minimize the number of roads and streets so as to maximize the livable square footage and thus the overall density of the intervention. By examining each plan, we can determine where each of the circulation systems lie and how much area each cell must offer.
Each cell on the plan is first offset according to the use of the streets adjacent to that cell. Once the new cell area is determined, a void is inserted to create the ‘courtyard’
The plan on the right shows how we can create vehicular ‘loops’ that allow access to each cell or at least to each cluster of cells. Once these vehicular paths are determined the rest of the streets can be used for narrower pedestrian functions.
The final cell configuration in plan view. The cells on the left only accomodate courtyard voids while the cells on the right have additional voids for streets. The voids add further porosity to an already optimized configuration.
STEP 8: Adding Circulation: Shaded Streets Once the offsets are complete we can begin to insert the streets within the voids. It is important to note that should a street span the entire void upon which it is placed, it would effectively negate any light that would have passed through that void to the space below.
The only guideline that is maintained is that the streets be placed along the Northern facades of buildings so as to shade them, similar to how a veranda operates in a typical courtyard house. Streets that operate on a N-S axis are located on the face that oriented North.
In order to allow light to pass through the voids, as well as for pedestrians to remain shaded it is important that pedestrian streets only cover part of the void and allow light to pass through the rest.
Pedestrian streets are placed on the Northern faces of cells as to shade them
View from within intervention showing shaded streets
Since streets do not fill the entire void, the leftover space allows light to filter down to lower levels
Circulation: Preliminary Tests
Initial circulation tests aimed to optimize a 3-dimensional road configuration that allowed access to each individual cell by car. Through this method we would be able to remove any redundancies with regards to road placement thus maximizing square footage available for living space. This method was later abandoned as the network was difficult to critique and intersections between levels did not take into account physical constraints such as a minimum turn radii, ramp ‘landing’ dimensions, etc.
STEP 9: Cell Organization
Each cell can be subdivided into smaller living units by observing some simple rules. A typical cell rests upon four cells from the grid immediately underneath its own level. Part of these cells sit within the boundary of the courtyard and the rest outside. The parts that are inside turn into terraces, the parts that are outside serve as paths to the unit entry. This ensures that each living unit has access to an outdoor space.
Each cell can typically be subdivided into 2 to 8 living units depending its size. Each division is unique and the resulting volumes offer a diverse range of living conditions to accommodate various demographics.
The cell rests on four cells below it. The part within it’s courtyard (green) functions as terraces while the outer parts serve as public spaces. The arrows point towards potential entry locations. A triangular ‘indent’ marks the entry to a unit.
Each cell is typically subdivided between 2 to 8 times. In this example the cell is split into 7 units. Each unit has a unique form and square footage.
2600 sqft 3200 sqft 2300 sqft
2200 sqft 3000 sqft
2500 sqft 4200 sqft
In this example, the resulting square footages vary from 2,200 sqft to 4,200 sqft. This allows for the occupation of a diverse range of residents that comprise multiple family sizes.
STEP 10: Structural System
There are two primary systems of construction that are used in the intervention. One is a system of triangulated trusses and the other a system of concrete ducts. The truss system spans the border of each cell and its members are divided such that vertical members between different levels line up to make it easier to carry the vertical load.
Typical truss layout for a group of cells
The structural ducts are located at cell corners and primarily support cantilevered spaces as well as vehicular and pedestrian circulation paths. The concrete ducts are responsible for carrying fresh air to each unit.
To demonstrate the logic behind the truss system let us examine three units, one on each level
Locations where cells intersect are mapped
Intersections indicate vertical truss member locations. Additional members are added to complete the truss.
Completed truss system
For a typical cell layout, the structural ducts are placed at the corners of the units
For example, at levels 1 and 3 the ducts connect to each other to form one continuous ‘tube’ Ducts that are close together are opportunities for the placement of windtowers
Level 2 ducts are generally independent from those above and below that level
Composite system of trusses and ducts
An elavation of the structural members of a cluster of cells
STEP 11: Facade Design
For the facades, a system of perforated panels was tested as a means of screening and concealment for each cell. Each facade on each cell is uniquely designed to operate for the local conditions around that cell. Privacy and thermal comfort play an important role in maintaining views and controlling light.
Let us examine the following cell on level 2
Each facade pattern is a combination of various different patterns The first is that of a gradient that is opaque towards the bottom and open towards the top. This is drawn directly from the vernacular
For each facade, we can calculate the annual solar insolation from our simulations.
The second pattern reacts directly to the thermal map above
The third map is the privacy map where specific areas of the facade are ‘blocked out’ to ensure that residents cannot look onto another’s private space and vice versa.
The resulting pattern is an average of the three maps. We can adjust the weight of each mapping so as to control their influence on the final pattern
Windtowers are placed over structural ducts at the corners of cells to ventilate interior spaces
Unlike the vernacular, the ‘street’ grid is independant from the direction of the wind
A lofted form unifies the two grids
The central triangular portion of the form is reponsible for ventilating and cooling public streets and plazas
The outer portion carries air to the cells
An arch within the form directs incoming air to the ducts.
STEP 12: Windtower Design As mentioned earlier, the windtowers now take a role such that they -Cool interior spaces -Cool exterior public spaces -Support cantilevered cells -Support circulation paths Each tower has a unique form. At the base, the form is determined by the arrangement of the structural ducts (that follow the optimized grid). At the top of the tower, the triangular form orients itself to the wind. Since the windtowers are placed over spaces that are between buildings, they are able to cool interior spaces as well as the public spaces directly below them.
Windtowers guide pedestrian and vehicular circulation throughout the intervention. Air travelling through the central vanes fall directly over public nodes.
Optimizing Windtower Distribution We have learned from the vernacular architecture of Dubai that the windtowers are situated above the load-bearing walls of the houses. This generally places the towers towards the outer periphery of the houses and within close proximity of neighboring windtowers (given that the streets between houses are narrow).
district receives fresh air as placement options are limited. Upon examination we see that the windtowers are distributed such that each receives fresh air that is not turbulent due to a tower upstream. Or conversely, no tower is placed such that the turbulent air it creates can affect the performance of a tower downstream from itself.
Intuitively, it would be quite a challenge to ensure that each windtower in the
A wind analysis of the Bastakiyya district shows that almost every tower receives fresh air despite the close proximity of the towers
Our intervention faces a similar challenge. Just as the original windtower’s placement was restricted to the load-bearing walls, our windtowers too can only be placed on certain locations. Thus it is important that we consider the effect that our towers can have on their neighboring towers downstream. In order to do this we must first simulate the effect of the turbulence of the tower. This is done by approximating the ‘turbulent cone’ that is formed as air passes across the tower We can examine the general behavior of a windtower in an air stream and approximate its effects in our digital model.
The next step is to place the windtowers on a predetermined grid and optimize the grid to accommodate 1) the maximum number of windtowers and 2) the minimum number of intersections between a tower and another tower’s ‘turbulent cone’.
The upper image shows a non-optimum condition where some windtowers are placed within the ‘turbulent cone’ of another tower, such as towers 2 and 13. The lower image shows a potential optimum configuration where turbulent air from a tower does not affect other towers.
Windtowers The towers draw cool air into the housing cells below and also cool the streets and public plazas that they rest upon. LEVEL 3 Housing cells that are optimized for maximum density while simultaneously allowing the maximum amount of light to filter to Level 1 and Level 2 LEVEL 2 Elevated circulation paths that access each cluster of cells can be used for vehicles and pedestrians LEVEL 2 Housing cells that are optimized for maximum density while simultaneously allowing the maximum amount of light to filter to Level 1 LEVEL 1 Public space weaves through the grid allowing a public promenade lined with retail and other services LEVEL 1 Vehicular paths grounding the grid within its context by establishing connections with neighboring roads and places of interest LEVEL 1 Housing cells derived from optimizing a grid for wind penetration
Conclusion This project demonstrates that optimization tools can produce efficient non-intuitive results that, if attempted by conventional means, may not have been possible. It also shows that these results may only be obtained by carefully setting up the problem parameters in order for the program to work. This requires an experienced understanding of the scope of the problem and to some degree the nature of the expected result. The setup must also take into account the range and number of variables so as to narrow the range of results and to reduce computation times. It should also be understood that obtaining an optimized solution is only a checkpoint towards a more comprehensive design solution as it is the intervention of the designer that transforms an otherwise ‘optimized computer output’ to a viable design strategy. Therefore it is understood that the most optimum result from the computer may not always be the best solution for the designer. The designer must at all times balance efficiency with parameters that are not factored into
the optimization process. An example is the use of the public space obtained from the grid optimization process. Here, public space is obtained by eliminated cells that fall below a minimum area threshold. This generally places the public ‘voids’ at random areas on the site. Thus it is up to the designer to use their discretion when examining the results in order to select/modify a public space configuration that ‘works’. As for the city of Dubai this project presents a viable alternative to the current built environment experienced in the city. Most of the cultural and environmental issues mentioned earlier in this book are addressed by the project. With regards to establishing an identity for the city the project manages to extract lessons directly from the vernacular architecture; an architecture that had been abandoned when it is perhaps the only example of an authentic architecture in the city. By densifying existing sites we can reintroduce services into communities at a scale that is walkable. Most new
developments necessitate that one would need to drive somewhere to get groceries, visit the mosque, etc. By optimizing the streets for wind, we can naturally ventilate public spaces as well as introduce fresh air to most of the interior streets. By introducing windtowers we can also cool interior spaces. Collectively this reduces the level of mechanical cooling needed to maintain comfort within the units. In addition the windtowers also aid in ventilating exterior spaces (streets/ plazas) drastically mitigating the heat island effect that is common in the city’s densely populated areas. By optimizing the cells for light we ensure that all residents have access to the outdoors and to natural light. This is not typical of a mid-rise or highrise typology unless units are located on the periphery. In our project, light is not sacrificed for density. The housing ‘cells’ obtained from the optimization process vary in scale and produce living units of various scales. This establishes a community whose occupants comprise families of various
sizes and demographics. Most buildings, in Dubai and otherwise, offer similar sized units that promote the occupation of a homogenous community. Custom facades are designed for each cell to improve their performance with respect to solar exposure and with respect to privacy as observed in the vernacular. Moreover these strategies can be applied at various scales. Our example shows a three-tier (60 feet) configuration that can easily be modified for more or less levels. The configurations also adapt to sites of all forms and scales as well. The strategies utilized in the project are all derived from the vernacular architecture of the region and thus bind the contemporary intervention to local roots. In a city that might be losing its identity such strategies are vital tools in reintroducing cultural values into the built environment without resorting to a motif.
Azhar Khan 386.383.8018 azharkg@gmail.com