The Design Issue

Architects Gordon Gill and Adrian Smith on Building the World's Tallest Towers


Burj Khalifa, Dubai

Photograph by Solent News/Splash News/Corbis

Burj Khalifa, Dubai

The Burj Khalifa in Dubai is a building of superlatives. At 828 meters (2,717 feet), it’s the tallest in the world, 227 meters taller than No. 2, the Makkah Clock Royal Tower in Mecca. More than double the height of the Empire State Building, the 163-story building took six years, $1.5 billion, 110,000 tons of concrete, and 22 million man-hours to build. But the most interesting thing about it isn’t any of these incredible statistics but the way it looks: Unlike most supertall buildings, the Burj is nice to look at. It’s not a workmanlike stack of boxes, like the 442-meter Willis (né Sears) Tower in Chicago, or a postmodern heritage trinket like the Makkah Clock Tower, which resembles a Big Ben souvenir someone might buy at Heathrow. The Burj Khalifa, a bundle of cylinders that aren’t uniform yet are formally organized, rises in a graceful spire. The New Yorker’s architecture critic, Paul Goldberger, wrote in 2010, when it opened, that “the profile of the Burj has a magnetism that is lacking in almost every other supertall building of our time.”

The building is the work of Adrian Smith, who designed it while he was still working at the architectural firm SOM, which he left in 2006. SOM—founded as Skidmore, Owings & Merrill—is a factory for enormous corporate projects, some of them inspired and some of them, like the Willis Tower, less so. But in the Burj, Smith managed to make something beautiful.

Gordon Gill (left) and Adrian SmithPhotographs by Matthew Avignone for Bloomberg BusinessweekGordon Gill (left) and Adrian Smith

Smith says of leaving SOM that he was 62 years old, the retirement age at the firm was 65, and he was looking at a final three years training his successors. Instead, he left and took a 10-year lease on an office with his personal savings. He brought with him a handful of colleagues, including Gordon Gill. As they arranged their new desks, they had no clients and no commissions, but that’s changed, to say the least. Among many other projects, Adrian Smith + Gordon Gill Architecture has designed the Kingdom Tower, now under way in the city of Jeddah, Saudi Arabia, just an hour from Mecca. When it’s “topped out” as Smith says, it will be taller yet than the Burj Khalifa and likely the first building more than a kilometer high.

“The developer of the Burj made most of his money on the buildings around it”

Smith was born in Chicago but grew up in San Clemente, Calif. He studied architecture at Texas A&M University, transferred to the architecture school at the University of Illinois at Chicago, and has been in the city ever since. He has blue eyes behind rimless glasses, and white hair hangs like bunting over his head, which seems to have been granted a little extra brain space on top. He often wears all black, but for an interview in March he’d lightened it up a bit, donning a gunmetal-blue button-down shirt with a preacher’s collar and a hidden placket. He seemed to be in a good mood, possibly because he was just back from Astana, the capital of Kazakhstan, where the temperature was about 30 below. There, President Nursultan Nazarbayev, who’s been in power since 1990, awarded Smith + Gill the job of designing the pavilion for Expo 2017, a $4 billion to $5 billion project that will generate all of the energy it requires.

The offices of Smith + Gill are on West Monroe Street in the former headquarters of the BMO Harris Bank (BMO). There’s a grand piano in the reception area and huge glass doors leading out to pleasant patios complete with reflecting pools. There are about 200 employees at the firm, scattered around in a mostly open floor plan. Smith’s office is behind a wall with no doors at the end of a long work area. There are windows on two sides and white walls without pictures. Gill’s similar office is just around the corner.

Gill, 50, grew up in Jamaica and moved to Toronto when he was 11. He wears his hair buzzed short and often seems gently amused. He, too, wears a shirt with hidden buttons, but his has stripes. In a passage not far from his office, models crowd a table and counters along the wall, replicas of Smith + Gill projects, most still in the design phase: Dancing Dragons, a pair of towers with shardlike facets running up the sides, to be built in Seoul; the Wuhan Greenland Center, a single convex tower planned for Wuhan, China; and a sprawling miniature layout of China’s Tianfu Ecological City, a future development outside Chengdu.

“In the science of supertall buildings, we’re still discovering things”

Supertall towers can become bankable tourist destinations. The observation deck of the Burj, on the 124th floor, sees more than a million visitors every year. The Empire State Building reported in a recent financial statement that it makes about as much money from visitors to its observation deck as it does from tenants’ rent. Children regularly send Smith letters expressing their admiration. “They love towers,” he says. “I get things all the time from kids. Usually they send a return envelope, and they want me to sign it and send it back.” He slides one letter across the table. Next to a hand-drawn rendition of the building dominating its shorter competition it reads, “I have a big poster in my room of the Burj Khalifa.”

Yet supertall buildings are also regularly mocked as pointless exercises in the lamest kind of local pride, and they’re the subject of jokes about the insecure men who erect them. The tallest buildings in the world also have a reputation for being hard to fill with tenants. The Empire State Building, completed during the Depression, was knocked for years as the Empty State Building. The World Trade Center was often looking for tenants. Both Smith and Gill counter that the economics of the supertall skyscraper are never about filling all the floors.

“They are conceived of as landmarks and can have a huge influence on where they’re being built,” Smith says. “The developer on the Burj made most of his money on the buildings around it, which gave it a center and a unique feature that no other planned village has. But because it was the world’s tallest building, it also gave identity to Dubai.” Chairman Mohamed Alabbar of Emaar Properties, the tower’s developer, said on the release of the company’s annual results for 2013: “Downtown Dubai, our flagship mega-development, has energised the property, retail, tourism and hospitality sectors, in addition to creating over 50,000 jobs since its launch.”

Smith + Gill is also a firm that takes sustainability seriously; it was awarded the Expo pavilion in Astana not only because it could build big but also because it could build green. Its reputation comes from a project the principals conceived to keep workers busy when several projects were halted during the financial crisis. They sent 50 idled architects to study the 50 blocks that make up the neighborhood in downtown Chicago known as the Loop. The result was the Chicago Central Area DeCarbonization Plan, and a book by the architects, Toward Zero Carbon. The city adopted the completely self-funded program as a road map. They asked questions such as: How tall is the most efficient building, if carbon emissions are accounted for in its materials as well as energy consumption after construction? The answer is a three-story walkup, which, among other things, does not need elevators and can be built with a low-carbon material such as wood. It is, says Smith, an interesting fact to live with for a designer of supertall buildings.
 
 
One doesn’t design a supertall tower, so much as find it: In its essence, such a building is just one of the few solutions to the many hundreds of problems the architect must solve. The most obvious and important problem is wind, which Gill calls “the governing design element.” A supertall tower mustn’t resist the wind nor let it move in an organized way around it. When wind goes around an obstacle, a vacuum, or vortex, is created on the back side. The wind collapses into this vacuum, causing pressure that can amplify or fight with the pressure of the wind on the front. When these forces build up, a structure can start to vibrate like the rigging on a sailboat. At the top of the 344-meter John Hancock Center just down the street from Smith + Gill, which Smith worked on as a young architect at SOM in the 1960s, chandeliers can sway, and toilet water shimmers.

Picking up a miniature Burj Khalifa in the hall, Gill zigs his finger along the outside of the model. The stepped risers that make up the building end in an irregular spiral which “destroys these vortexes,” he says. Shedding the vortexes, as it’s called, “prevents the flow from getting organized, so the building never gets into any kind of harmonic motion,” Gill says. “It confuses the wind.”

Wind tunnel testing has become integral to the design of tall buildings, and the models are blasted with turbine-generated gusts of up to 55 meters per second (about 120 mph) while hundreds of sensors register differing pressures. Testing a design in a wind tunnel can cost as much as $100,000, but it has helped Smith and Gill learn a lot about how supertall buildings respond to the wind. “We recommended the spiral stepping, and it turned out to be a good move,” says Smith. “It gave more variation to the profile of the building from the point of view of the wind. Each time you have a different width or setback, it changes the frequency or the size of the vortex. It hadn’t come up before. In the science of supertall buildings, we’re still discovering things.”

Understanding wind continues to change the design of these mammoth structures. Whereas Smith and Gill first thought primarily in terms of resisting or baffling the wind, they now think about harvesting it. The 310-meter Pearl River Tower in Guangzhou, designed by Smith and Gill when they were both still at SOM, includes wind turbines: This not only provides energy but also helps solve the vortex problem. Pearl River is one of the greenest buildings in the world, though it’s also the headquarters for China National Tobacco, the world’s largest maker of cigarettes.

The shape of the base of a building like the Burj Khalifa or the Kingdom Tower in Jeddah is also an answer to a practical question. The base must obviously be wide enough to support the immense structures above, and while a square base is easily enough built, someone standing at its center might be dozens of meters from a window. That’s barely tolerable for office workers, who are paid to be there, but the Burj and the Kingdom Tower are largely residential projects, and condo buyers don’t want windowless cubicles deep inside a hive. Smith and his team solved this by designing both in a Y-shape, with fins extending out. In this way, the base is as wide as a Chicago city block, but all parts of the floors are near windows. It’s a design whose inspiration is close to home—Chicago’s Lake Point Tower uses this plan—and one Smith had used before on the 264-meter Tower Palace III in Seoul.

Money and vision aside, the height of a building can be limited by more prosaic matters, such as the weight of elevator cables. As building height increases, the cable gets heavier; the Burj is near the maximum height a single elevator can travel without being insupportable. Kone, a Finnish company, has announced the design of a lighter carbon-fiber elevator cable that will make heights of up to 1,000 meters possible, but it has yet to be deployed. In the Kingdom Tower, double-deck elevators will go to the observation level on the 157th and 158th floors. The final element governing building height, though, may not be mechanical or even financial. There may be a limit to the rapid change in height the inner ear can stand. At extreme heights, an elevator might need to be designed to go slower than one might want, or to rest at a middle floor. But that’s not something condo buyers are likely to favor. Asked if he’s ever worried about the discovery of an unforeseen challenge or phenomenon only after a tower has topped out, Gill smiles, pauses, and says simply: “Yeah.”

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Urstadt is an editor for Bloomberg Businessweek.

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