In the Supertall! exhibition at the Skyscraper Museum in Lower Manhattan [on view July 27–February 19, 2011], we set a benchmark higher than the standard 300 meters used by the Council on Tall Buildings and Urban Habitat (CTBUH). To be included in the show, the building had to be at least 380 meters (1,250 feet)—the height of the Empire State Building—and likely to be topped out by 2016. (It takes an average of five years to complete a supertall.) Forty-eight projects met these criteria for the show.What is your definition of a “supertall” building?

With design of the Kingdom Tower in Jedda, Saudi Arabia, by Adrian Smith + Gordon Gill Architecture at more than 3,280 feet, we are seeing the bar raised so much higher. Why are so many supertall buildings springing up in Asia and the Middle East? Besides the money being there?

ON A CLEAR DAY On the 157th floor of the future Kingdom Tower in Jeddah, Adrian Smith + Gordon Gill Architecture has designed a 5,800-square-foot projecting, outdoor terrace (above), part of which will have a glass bottom. An observation deck also is planned for the 123rd floor. The reinforced-concrete tower, sheathed in high-performance glass (below), will taper to a height over 3,280 feet.

VIEW FROM THE TOP The three-legged massing of the reinforced-concrete Kingdom Tower provides stability, while the large notches in the tower help shade terraces from the sun. No facade faces the sun directly, and the outdoor air temperature at the top of the tower is expected to be lower than that at ground level. The 5.7 million-square-foot tower, with 59 elevators and three sky lobbies, overlooks a waterfront district, which Smith and Gill are master-planning as a part of the new development of Kingdom City on the Red Sea.

The context is important with regard to tall buildings. In a place like Hong Kong, which encourages skyscrapers, the government owns the land and can gain high bids from developers by allowing what I call “vertical-density” development. Projects such as International Commerce Centre by Kohn Pedersen Fox [page 142] are part of a centralized urban-planning and development scheme that includes transit hubs, offices, housing, and retail.

In other cities with less sophisticated infrastructure and technology, supertalls are used to create an autonomous urban place with complementary uses for business people—offices, hotel, apartments, and shopping. This is a fully acclimatized environment with reliable electricity and other services—even if the local grid is not reliable. These buildings are advanced machines of efficiency that serve a lot of people in a small space.

Urbanization in China is so explosive that many cities have populations as large or larger than New York City's 8 million. Chinese cities offer a huge, growing demand for new buildings. Yet in the Middle East—for example, Dubai—developers try to create demand by designing tall buildings that will attract affluent buyers and investors in real estate. The idea is that glamorous buildings can create demand.

Is the role of the private developer the same as in the United States?

Governments often play an important role in Asia and the Middle East, either selecting developers or investing and building themselves. For example, with the Shanghai Tower [page 156], Gensler is working with a state-run construction and investment company. I think the tower will make money, but it's hard to compare Shanghai Tower to one developed by a purely private market.

How have American architectural firms gotten into the supertall inner circle of skyscraper designers? Obviously we can claim having been there first with our skyscrapers built in the late 19th century in New York and Chicago. But on our home turf we haven't been doing towers at this scale.

American architects and engineers had an edge when the global embrace of skyscraper design began about 20 years ago. Experience clearly matters in doing a supertall. Designers lead a team, and its members know each other and often work together in problem solving to build a better skyscraper machine. Understanding the challenges of designing a curtain wall, elevators, floor plans, and rentable floor area takes experience.

So how would Gensler get the commission to design the supertall Shanghai Tower since it had never designed anything higher than 54 stories (the L.A. LIVE, 2010)? Gensler might be the second-largest architecture firm in the U.S. in terms of revenue [Record, July 2011, page 24] and it has over 3,000 employees, but, as we know, a small coterie of American architects—along with Foster + Partners and others—gets these jobs. So far Gensler hasn't been part of the cloud club. Also whether the firm likes it or not, Gensler is better known for its commercial interior design work than for tall buildings.

As I understand it, Gensler builds relationships and trust, starting with interior design work for corporate clients, and then it pushes the boundaries from the office to the whole building. It builds trust with clients by coming in at the ground floor, so to speak. Gensler also has hired people and has assembled a team who had worked on supertalls elsewhere, such as SOM. Also it worked with Thornton Tomasetti and Cosentini Associates for the engineering of Shanghai Tower. I heard Arthur Gensler represented the firm for official meetings and ceremonies—which makes a strong impression with the clients.

Does it make sense to keep going higher, as we see with the Kingdom Tower? The architects involved in supertalls talk about sustainability values of such density and agglomerating various forms of transit within the project.

A lot of conditions are cultural. I was just in Frankfurt, a city that likes skyscrapers, but where retrofitting and recladding towers built in the 1960s to 1980s for energy-efficiency is an important trend. In terms of the supertall sustainable skyscraper, the next step is toward net-zero energy—that is, towers producing as much energy as they consume. This idea is already starting to happen with shorter towers.

Isn't there a point when a supertall is just too tall? Even if it is energy-efficient?

A lot of people believe supertalls are irrational acts. I think they are fundamentally rational, but also aspirational. To build a supertall you are taking a risk, more than if you were building a conventional structure, but you are trying to do something that gets extra attention. These bigger-than-life skyscrapers are beautiful. Supertalls are the celebrities of the skyscraper world.

Super Supertall: Kingdom Tower

Kingdom Tower, the ultra-seductive crown of a new development—the 1,312-acre Kingdom City, in north Jeddah—got its final building approval in February. Currently it is undergoing load testing for soil conditions and has completed its test pile program.The tallest supertall in the world, Kingdom Tower, in Jeddah, Saudi Arabia, is expected to zoom upward of 3,280 feet (over 1000 meters) when completed in 2017. But Adrian Smith + Gordon Gill Architecture won’t say how much “over” that height it will soar. It could be the competition thing. Ever since the first tall buildings started breaking height records in New York in the late 19th century, architects and their clients have vied for the tallest-in-the-world title. If technology and money can provide the wherewithal, the adventurous will want to go ever higher, wrapping desire within rationales (e.g., solving population density, saving energy).

Smith, who was the lead designer of the world’s tallest tower—the 2,717-foot-high Burj Khalifa in Dubai (2010)—while he was a partner at Skidmore, Owings & Merrill (SOM)’s Chicago office, left in 2006. He joined up with Gill, an SOM colleague, and soon the new firm was invited by Prince Alwaleed bin Talal of the Kingdom Holding Company (KHC) to compete for the reportedly $1.2 billion tower overlooking the Red Sea. In 2011, Smith and Gill won the coveted commission over high-flyers SOM, Foster + Partners, Kohn Pedersen Fox, Pelli Clarke Pelli, as well as Pickard Chilton, Atkins, and Henning Larsen Architects. And while HOK is master-planning Kingdom City, Smith and Gill are in charge of the 57-acre waterfront district around the tower.

Smith maintains the scheme—a reinforced-concrete three-legged structure, designed with engineers Thornton Tomasetti—won the day because “it was cost-effective, efficient in the floor plan, and dynamic to look at from all vantage points.” Like Burj Khalifa, Kingdom Tower uses a basic tripodlike form to spread the load. But this tower’s tapering slope, Smith notes, helps reduce wind load more effectively than the Burj Khalifa’s stepped profile. “The slope mitigates vortex shedding,” says Smith, pointing out that every floor sets back from 4 to 8 inches as it inclines upward.

The tower, clad in high-performance glazing, will contain a mix of offices, hotels, condominium units, plus “service” condos maintained by the hotel, not to mention retail and observation decks. Currently Smith and Gill have a supertall just beginning construction in China—the Wuhan Greenland Center, at 1,988 feet high—with another, the 1,476-feet-high Yongsan tower, planned for Seoul. “It’s exciting to design a building that is going to be a landmark,” Smith says. “I look for a form that will function well and represent the country’s growth and cultural leadership.” Suzanne Stephens