Soaring to the sky - Emirates24|7

Soaring to the sky

The materials for the exterior were selected with both low maintenance and longevity in mind. (XAVIER WILSON)

The Burj Dubai, developed by Emaar Properties, will open today, January 4, 2010 – the fourth anniversary of the accession to power of His Highness Sheikh Mohammed bin Rashid Al Maktoum, Vice-President and Prime Minister of the UAE and Ruler of Dubai.

Emirates Business, part of Dubai Media Inc, is marking the event by taking an in-depth look at the tallest building in the world. The tower has transformed the world of tall buildings and catapulted Dubai onto centre stage among the international architecture and construction fraternity.

This souvenir issue showcases the processes involved in the creation of the project, starting from the design brief and moving on to the structural engineering challenges, site-specific challenges and the construction site realities.

We spoke to the various companies that formed the project team. And what better way to start than with an interview with the Burj Dubai's design architect, Adrian Smith, who formerly worked at the Chicago office of Skidmore, Owings & Merrill (SOM), the firm that won the design competition.

Smith, who has now moved on to set up his own practice Adrian Smith + Gordon Gill Architecture (AS+GG), charts the progress of the design process to date.


What was the initial client brief and what was your design interpretation?

AI became involved with the Burj Dubai when the developer, Emaar Properties, invited the Chicago office of SOM, where I was a design partner, to participate in a design competition in early 2003. The form of the building is geometric in plan, starting with three branches and three pods. Setbacks occur at each programmatic element, decreasing the tower's mass as it rises towards the sky. At the tower's top, the central core emerges and is sculpted to form a finishing spire. Views of the Gulf and city are maximised throughout the building through the use of a Y-shaped floor plan inspired in part by certain early designs by Mies van der Rohe, Chicago's Lake Point Tower and my own design for Tower Palace III in Seoul, South Korea. The client definitely wanted the Burj to be the world's tallest structure. But I was also attempting to create a building that would stand as a lasting landmark whose iconic status transcends the issue of height. In developing the initial concept for the Burj Dubai, I searched for elements within the existing context and culture of the area to reflect on and draw inspiration from. Within the Middle East and Dubai there are strong influences of onion domes and pointed arches and patterns that are indigenous to the region, some of which are flower-like with three elements, some with six, and so on. Other influences include spiral imagery and the philosophy embedded in Middle Eastern iconographic architecture and motifs. These motifs have their origin in organic growth structures and plant materials. The form is geometric in plan, starting with three branches and three pods. The specific shape of these branches is modular in nature and in function, and organic and biomorphic in form. The form can be found in flower petals, leaves and seeds, in animals such as birds and in sea creatures including crustaceans. The overall composition is a vertical object reduced and transformed by spiral reduction of branch lengths until it reaches its central shaft, at which point the shaft peels away to reveal a triptych configuration that erodes in a spiral manner until a single spire remains. The resulting impression is organic and plant-like. This typology is indeterminate in its size and can be expanded vertically by adding modules to its base or continuing to divide the spire element. I would also note that it is important for architecture to reflect the ethos of its location; otherwise you end up with cities that don't look much different from any other city in any other part of the world. My own approach to architecture has always been that of a contextualist, which is to say that my designs take into account the history and culture of the societies they serve. In plan, although not in elevation, the Burj Dubai refers to the onion domes of Islamic architecture, for example in the rippling patterns of the façade there are references to both the Gulf and the surrounding desert landscape.

Did you have the freedom to create as a designer and was Emaar the ideal client?

First of all, it started as a competition. That itself gives you a certain challenge. In respect to that challenge, you do have the freedom to show them what you think you should do and that gives you a certain freedom to create without client input, which does come after the competition. And as such, they recognised our scheme as a buildable scheme – one that was not so extraordinary or impossible to build that they would have all sorts of difficulties in the future. They identified the fact that it was a buildable scheme and then began to put a more specific programme into that scheme, which effectively allowed us to develop the scheme into a workable building. A wonderful aspect of working with Emaar on this, and in particular with Chairman Mohammad Ali Alabbar, was that they understood the element of time in the design process and allowed us to work the concept to the point of completion. Even when we had a rough scheme of 700 metre, I knew that this scheme was not right and not complete and kept working on that. When I showed Alabbar a scheme that was somewhat taller, he recognised that it was important to the project and accepted those ideas even though it was at an additional cost to him. That was the biggest aspect of this whole process and that is rare among clients. So he is to be congratulated in regard to that aspect.

Could you elaborate on the design intent?

When conceiving the building, I really wanted it to look like it was growing out of the earth, that it was emerging from the soil. It plants itself in a way that it is like a tree with the roots reaching out to the ground to anchor it. The legs come down and then move out and create a larger podium for the building. And so in that sense it is more organic. The goal was to create an organic piece that looked rooted in the environment in some way and that grew out of the ground. The interiors follow through with that organic quality with the sense of fluidity in the lobby and the transition from the larger spaces to smaller spaces and then to the elevator system within the residential building. Hence, the interiors are working with the architecture of the building.

Did you try to innovate through the use of materials?

No fundamentally new or untried technologies, materials or systems were used in the Burj Dubai. What was new and innovative are the ways they were used to optimise performance. The materials were selected and systems designed with both low maintenance and longevity in mind. Additionally, the design focuses on several unique problems posed by super-tall buildings. Coordination of the results of wind tunnel testing and concerns about the stack effect led to the development of special elements and mitigation strategies within the building and on the many building terraces. Window washing and the need to maintain the building's exterior wall led to the design of a system that incorporates over a dozen specialised mechanised units at several levels of the tower. Other innovative uses of materials and systems include:

• High-efficiency lighting

• Reduction in urban heat island effect with large water features and extensive landscaping above the garage podium roofs

• Use of site-wide gray-water system for irrigation including recovered condensate

• Cooling of incoming water by condensate recovery system

• Minimise the vertical chilled water transfer loop; the Burj has one of the highest chilled water pressures in the world, for chilled water energy savings

• Use of ventilated double wall system in the entry pavilion

What about designing for the wind? This is a significant aspect that affects tall buildings.

We conducted extensive wind tunnel tests to ensure the tower would perform optimally in response to weather conditions. In response to the tests, we sculpted the tower's shape, in particular by staggering the setback heights, to shed the negative forces of the wind moving around the building, which we call "confusing the wind". We also took steps to mitigate the stack effect, which in the Burj means that, due to the height of the building and difference between the internal and external temperature, indoor air tries to travel downward and flow out of the bottom of the building. To address this issue we minimised the infiltration/exfiltration of the exterior wall. We also created a sky lobby elevator system in which the shuttle and local elevator shafts are separate and did the same with the shafts enclosing the exit stairs. In effect, the building acts as a series of shorter, separate buildings stacked on top of one another.

How did you treat the massing and the raising of the heights?

The massing and height of the building are closely related. Emaar was interested in making the Burj the tallest building in the world, but that standard could have been met with a building much shorter than the one we ended up designing. But I envisioned the Burj as a very elegant, slender building, and resolving the design in an appropriately proportional way required a great deal of height – quite a bit more than Emaar had originally expected. In the end, the height of the project was changed from 700 metres to "something taller" when we changed the massing at the tower's top. There will be a final, definitive height at some point, but the truth is that no one really knows what the final height will be until it's announced by the developer. The Burj will continue to be the world's tallest building for at least five years, since no announced projects of greater height have actually broken ground yet, and it will take at least five years of construction for another tower to exceed the height of the Burj. When a taller building does come along, the Burj Dubai will retain its iconic status, which does not depend on its height.

Many tall buildings internationally are proposed and designed but do not get off the drawing board. Is it possible to design a tall building that is financially feasible?

One of the key concepts we developed in Chicago, and then introduced to the local authorities in Dubai, was the concept of advanced occupancy. Simply put, it allows for the beneficial use and occupation of completed portions of large projects, well in advance of completion of the entire project. In the case of a super-tall building like the Burj Dubai, with an overall construction schedule of more than five years, the application of advanced occupancy permits the owner to generate revenue from completed portions of the project starting about the midpoint of the construction schedule. This early start of cash flow compares favourably what would be expected with much smaller projects, therefore substantially reducing the owner's debt burden. To accomplish this, all parties – the owner, the contractor, the designer and local authorities – had to agree on the concept and be willing to implement a structured, comprehensive and logical programme to achieve it. The building was designed to facilitate this approach, but unfortunately due to circumstances, the local authorities would not permit advanced occupancy on the project.

Are tall buildings sustainable?

Skyscrapers are inherently sustainable because they accommodate a large number of people on a small footprint of land. They also offer efficient vertical and horizontal transportation systems, encouraging the use of public transit and creating increasingly walkable cities. Super-tall buildings can also be formed to further decrease their environmental effect and become "super-sustainable". These structures can take advantage of the faster wind speeds at higher altitudes and drive wind toward building-integrated turbines to generate power. Because they are less likely to have shadows cast on them, high-rises also make efficient use of building-integrated photovoltaic systems to absorb solar power and generate energy. And deep foundations make them ideal for geothermal heating and radiant cooling systems. The Burj Dubai is not widely credited for its array of sustainability features. Initially, we did not define a sustainability programme. That is embedded in the work that we do anyway. There are a couple of new additions such as the condensation collection system that was added by our engineers, but we did not go about the process of making it a Leed silver building. We knew that it would be sustainable by the very nature of what we do. In fact the building's form and systems responded in a variety of ways calculated to perform optimally in its environmental context. In response to wind tunnel tests, for example, the tower's shape – particularly its setback pattern – was sculpted to shed the negative wind forces moving around the building. Other aspects of good practice and sustainability incorporated into the design include:

• A station for the Dubai Metro is being incorporated into the development. There also will be a local trolley service along the Boulevard to serve the project. Indeed the Burj Dubai was the catalyst for these transit features, which will serve the entire city, to be built.

• A high-performance window wall system with thermally broken aluminium frames and insulating glass with selective coatings provides a low shading coefficient while maximizing natural daylight and views.

• Intake of outside air at higher altitude takes advantage of temperature drop at higher elevations.

• Natural ventilation of spaces is utilised where possible.

• Use of a site-wide grey water system for irrigation including recovered condensate.

• The Burj is one of the first towers in the world to apply extensive stack effect mitigation strategies at design stage.

Do you feel that the design interpretation has been true to the concept?

Yes I do. We actually developed the design and detailed it and we knew exactly what we were going to have before building. We did a lot of modelling and so it wasn't a surprise when it was finished. There is always an element of surprise as to what the scale of a real building does to your ideas and that is where the real interpretation of the building comes in. It is also where you get a bad or a good surprise. Here it is a good surprise. I did not get involved in the ground realities of construction. Hyder was involved in making sure that the construction was true to our construction drawings. So I was not surprised about the building because nothing changed in the design in any material way.

What materials are used in the tower's exteriors?

The materials for the exterior were selected with both low maintenance and longevity in mind, given the harsh local environment. The exterior wall materials consist of high performance insulating glass units, installed in a unitised, aluminium framed system with polished stainless steel mullions and patterned stainless steel spandrel areas.

The building has very interesting night lighting. Could you explain how that effect was created?

At grade, the site was developed into a terraced field of fountains and geometric islands connected by landscaped walkways. The design of the typical night illumination for the tower concentrated on accenting the setback terraces as they progress up the building. Additional "festive" lighting was incorporated onto the tower, which mainly consists of a field of strobe lights with increasing density as they approach the top.

How did you address the issues of exits, entries and parking in this high-density site?

The public enters the site at an intersection and roundabout with a special water feature off Burj Dubai Boulevard. After I left SOM to launch AS+GG, Emaar commissioned us to design the Burj Dubai Gatehouses, a series of six security facilities that control access to the tower. Positioned at various points around the tower, five of the gatehouses are oriented to the development's hotel, residential, office and service entrances. A sixth gatehouse serves as a taxi stand. Each gatehouse contains an equipment room, washroom and a cabin with seating area for attendants. They also conceal large-scale security scanners that X-ray incoming cars before they are allowed onto the property through boom gates. The curvilinear geometry of the gatehouses' stainless steel armature echoes that of the Burj Dubai itself. The armature also features teakwood accents that create shade and make the environment cooler for the attendants. The gatehouse cabins are each about 50 sq m each and between three and four metres tall. They are oriented to maximise views of incoming cars and pedestrians.

How did you go about planning the vertical transportation for this mixed-use project?

The tower can be likened to a small vertical city. It contains residences, places of work, hotels, restaurants, retail shops, amusement areas, revenue-generating lease areas and all the spaces and equipment necessary for the aforementioned to function properly. Furthermore, similar to but beyond the needs of a small city, the arrangement of the various functions must be rationalised along with the means and methods of transportation of people, energy, goods and materials. The building utilises high-speed non-stop shuttle elevators bringing passengers to sky lobby floors where they transfer to local elevators serving the floors in between. This is similar in concept to the "express" and "local" commuter trains used in cities around the world. The design of the system must correspond with both the type of use of the floors served and the physical configuration of the building. The location of the sky lobbies and the type, use and number of local floors being served from those sky lobbies must be taken into account when the size, speed and number of elevators are calculated. It's critical that a balance is struck between all these factors in order to optimise the vertical transportation system and minimise the amount of space the elevator shafts and lobbies occupy. The key to the efficiency of space usage is to stack the local elevators serving the different zones of the building on top of each other. In order to accomplish that, a gap of several floors has to be designed into the structure in order to accommodate the required elevator pits, over runs and machine rooms for each group. In order to maintain the efficiency of the building, those gap floors, although not accessible by the public, are gainfully utilised as space for mechanical and electrical services. With respect to fire and life safety, we went beyond the local building code by implementing strategies such as "lifeboat" elevator evacuation, introducing areas of refuge and conceptualising an advanced evacuation communications methodology developed along with the crisis management plan for the project. Furthermore, being the tallest building in the world and being constructed in a post-9/11 world, from the start it was agreed that going beyond the code also included certain security enhancements that we conceptualised and implemented on the project but cannot discuss here.

What about the landscaping for the project?

We did not have much to do with the landscaping. We did a site plan, which began to draw a geometric pattern out into the landscape. When SWA got involved they simplified that in the process and it really works with the building (see page38).

What were the solutions to challenges that arose during the actual construction?

In a few cases it was necessary to tweak the design during construction. For example, it was necessary to redesign the elevator system and re-stack the tower while it was under construction due to a late programme change by the client.

What next for Adrian Smith?

We're pursuing several projects in the Gulf, most of which are still confidential. At my new firm, AS+GG, Gordon Gill and I look first at the environmental context of our projects, but the art, vernacular architecture and indigenous materials of our buildings' sites also have a strong influence on our thinking. Masdar Headquarters, our project now under construction in Abu Dhabi, is inspired in part by Arabic wind towers. It will be the world's first large-scale positive-energy building, generating 103 per cent of the energy it needs to operate. Among its signature features are a series of 11 giant cones which provide natural ventilation and interior daylighting and form courtyards and other amenities at their bases and the world's largest solar panel array. Gordon and I are extremely pleased that Masdar HQ will also be the home of the International Renewable Energy Agency, an intergovernmental organisation for promoting the adoption of renewable energy worldwide. We also have an increasing presence in Asia, with several projects in China and South Korea, including the new head office of the Federation of Korean Industries in Seoul, which features an innovative and highly sustainable exterior wall designed specifically for the project. In addition we're working on a green retrofit of the Willis (formerly Sears) Tower in Chicago, making it much more energy-efficient, and also designing a new green luxury hotel next to the Willis Tower.

 

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