Obituaries for the skyscraper were written after the terror attacks of September 11, 2001, targeted New York’s tallest buildings. It was argued then that tall, prominent buildings were too risky. It was said they made less sense in a wired-together world that is moving us toward—in the parlance—more “distributive” business models, making the centralized model of downtown obsolete.

Tall buildings, instead, seem to be bigger news than ever. In Europe, skyscrapers are the lab benches for sustainable-technology innovation. In Asia—especially in China—not only are towers erupting everywhere, the quality level is ramping up rapidly, according to Brian Lee, a partner in the San Francisco office of Skidmore, Owings & Merrill. In terms of energy conservation and workplace amenity, in China, “the next wave of expectations is that the quality of constructed performance will be as good or better than any buildings around,” Lee says. The Jinling tower, proposed for Nanjing (right) is only one of perhaps a dozen ultrasophisticated SOM designs in China.

Asia is “the natural environment” of the skyscraper, said Carol Willis in a recent interview at Manhattan’s Skyscraper Museum, which she founded and directs. “Skyscrapers make sense where density and the urban infrastructure make it the logical way to occupy land.” High density is already an accepted norm in much of Asia. The huge boulevards and freeways being flung into the countryside around the biggest Chinese cities are accompanied by commuter rail lines and subways. It’s why, says Willis, “you see towers still going up in Hong Kong, Guangzhou, and the other high-growth cities.” The tallest, densest buildings rise over rail stations—preferably with airport access—whether in Hong Kong (KPF’s 108-story Kowloon Station Tower) or London (Renzo Piano’s 1,016-foot-high London Bridge Tower—shown right).

America’s tall-building love affair has cooled, but such international developments are beginning to influence corporate decision-making here, especially regarding sustainable design. As projects featured in this issue make clear, the future of the skyscraper seems assured in New York City, even though soul-searching went deepest in Manhattan after the loss of nearly 3,000 peoples’ lives in the Twin Towers disaster. Towers today may be more sculpted and more individual in form than ever, but the argument Willis made in her essential history of the skyscraper, Form Follows Finance (Princeton Architectural Press, 1995), still holds: the dramatic shapes reflect both evolving ways businesses use their facilities and the evolution of central business district economies.

Downtowns as nexus of human networks

The 40-year ebbing of American central business district population and influence seems quietly to have halted. Even Manhattan showed remarkable resilience as a business location, according to recent research conducted for the Russell Sage Foundation. “Three years after the attacks, financial firms have by and large decided to stay in Manhattan,” explained Franz Fuerst, one of the Sage researchers, who is a research associate at the City University of New York’s Graduate Center. In correspondence with record, he noted that even Cantor Fitzgerald, a trading firm that lost two-thirds of its employees in the collapse of the Trade Center towers, will move into new quarters in midtown. Goldman Sachs recently unveiled a $1.8 billion new headquarters, designed by Pei Cobb Freed partner Harry Cobb for a site near Ground Zero.

Why does the city retain such appeal to firms that were so damaged by the terror attack? These same businesses, according to a recent New York Times report, are spending $3.8 billion annually on security and disaster contingency planning. The key factor for financial firms, according to Fuerst, “is the tremendous importance of access to sensitive knowledge through face-to-face interaction and a tightly woven network of personal relationships between industry professionals, clients, suppliers, and other decision-makers.”

Finance is one business that recognizes the degree to which it relies on human networks and the settings that, Fuerst wrote, provide “access to sensitive knowledge”—restaurants, clubs, gyms, industry events. “The type of information needed to assemble highly complex financial deals and new products simply cannot be obtained via e-mail or phone,” Fuerst added.

The Russell Sage researchers add to emerging research on so-called agglomeration effects, which is wonkspeak for the reasons businesses choose to locate near each other. Such research points to a new economics of place. A postindustrial business may depend less on easy access to natural resources but now relies more on human access and intricate human networks. (Consider how many consultants it now takes to design even ordinary buildings.)

These kinds of changes are rippling through the entire urban economy. It is just dawning on a lot of people that a peculiarity of our wired world is that we spend more time meeting with people and can never seem to get our “real” work done. The idea of having most of those people close by seems more necessary, not less.

Reconciling amenity and efficiency

European cities, traditionally hostile to tall buildings, are reinventing the skyscraper downtown. In London, decades of resistance to skyscrapers is crumbling, and perhaps a dozen new towers have been proposed in the historic center. Frank Duffy, of DEGW, a consultancy that tracks workplace change in both London and New York, put it succinctly: “The city learned it needs to have a diverse stock of buildings to survive.” More important, the center remains desirable, not merely for business efficiency but for prestige, and because the notion of needing to be at the center of things is far more ingrained in Europe.

Central London’s new towers fall far from the developer norm, however. Like 30 St. Mary Axe (RECORD, June 2004, page 218 | architecturalrecord.com), the towers are urbanistically polite: they are slim and not too tall (to avoid casting deep shadows on surroundings), and flaunt their use of sustainable technologies and efficiency-enhancing amenities (daylight, informal meeting places, individually controlled natural ventilation). One reason is that people working in today’s downtown tend to be highly paid specialists, and an amenable office has become part of what attracts talent.

American developers and large tenants have resisted the thin Euro towers with their small floorplates. They are costly and you can’t gather enough people on a single floor, the argument goes. Some recent proposals address that criticism: Grimshaw’s Minerva building (shown right) , Murphy/Jahn’s Deutsche Post tower, near Bonn (shown right and RECORD, May 2004, page 96 | architecturalrecord.com), as well as the Highlight Munich Business towers (shown right) mix amenity and space efficiency.

Higher first costs in Europe and Asia are not conceived to be the burden they are in America. Oliver Tyler, who has worked on several tall-building proposals in the London offices of Wilkinson Eyre, commented, “Better design is reflected in rents.” As important, “You get through planning permissions more quickly.” Though London’s gamut of approvals is daunting, most of the proposals, some made years ago, remain in play. The reason for optimism has to do with the city’s solidifying position as Europe’s key global hub. It has definitively eclipsed Frankfurt as Europe’s financial-services capital. There’s one reason, says Duffy: “Because it has more people with more skills in one spot.”

London’s success highlights another irony of a wired and “distributed” global economy: it is making large, hub metropolitan areas more important than ever—those places that have the depth and expertise that cannot be found anywhere else. America’s largest cities—New York, Chicago, Los Angeles—are consolidating their global-hub status. The idea that businesses must cluster downtown has seemed quaint in this country for a decade or two. The assumption has been that technology would liberate us from the inconveniences of the congested center, an assumption that the business disruptions of 9/11 only seemed to confirm.

Like the paperless office, this long-predicted future has not yet come to pass. Instead, businesses seek to bring the interactive urban business culture inside the office building. “What’s important is the permeable boundaries, the way people move from one organization to another in their workday, meeting people,” explains Duffy. “Mapping movement patterns would give a sense of the intricacy of business relationships, as well as the degree to which they now depend on face-to-face encounters and serendipitous meetings.” Unfortunately, most companies encourage interaction by cramming more people closer together in smaller cubicles. “We don’t know how to model” that intricate dance of idea-generating encounters, confesses Duffy. But most companies do know how to count up dollars spent per square foot on rent.

America’s predominantly suburban white-collar business model doesn’t ease intense interaction. You not only have to get in the car to see anyone, the trips are getting longer and more congested. Even “densifying” suburban downtowns isn’t easy. “They tend to be podlike, with a single point of entry,” said Robert Lang, interviewed at the Alexandria, Virginia, office of Virginia Tech’s Metropolitan Institute, where he is director. He spoke of employee resistance to a large-company consolidation outside Atlanta. Just getting off the freeway now takes 20 minutes, they argued, don’t make it worse. “As these places infill,” Lang adds, “congestion goes up more quickly than density”—giving a new edge to downtown.

Mixed use comes of age

“A skyscraper can be an acre on a floor, two dozen acres altogether,” says Ken Yeang, principal of Hamzah & Yeang, who has pioneered eco-towers in both temperate London and tropical Kuala Lumpur. “If you spread all that space out, you can only think of it in terms of urban design.” This leads naturally, he thinks, “to more amenities, more social opportunities.” Such tower innovations as sky gardens and atrium spaces for casual meetings over coffee are trickling into the U.S. market. Open stairs are tucked into the floor edges in the design Renzo Piano has made for the New York Times—encouraging idea-sharing by giving these meeting places the choicest real estate.

Yeang goes farther, urging in his designs and his writings a mix of uses that collide in garden spaces chopped out of the tower bulk. (See Reinventing the Skyscraper: A Vertical Theory of Urban Design, 2002, John Wiley & Sons.) Mixing uses in towers, once rare, is rapidly becoming far more common.

New York’s recently completed $1.7 billion, 2.1-million-square-foot Time Warner Center may take the prize for diversity. Behind its tinted-glass skin, you’ll find a four-level shopping center over a basement supermarket and health club. Two office chunks perch atop the mall, one devoted to Time Warner (including studios for CNN) and one tenanted. The just-opened Jazz at Lincoln Center glows in the middle from behind a five-story-high square of glass suspended by cables. A residential tower rises above Jazz to the south. The north tower includes a 251-room hotel and more condominium apartments.

The advantage for the Related Companies’ Steve Ross, who developed the massive project, was that the various uses balanced the financial risks, according to Gregg F. Carlovich, a Related resident manager. (For a history of the project, see RECORD, June 2003, page 86.)

Time Warner Center’s quiet, bespoke exterior clads dizzying complexity. “Each use has its own structural and mechanical solution,” explained Mustafa Abadan, the design partner for the project. So the massive loads from the concrete-frame-and-shear-wall structure for the hotel and residential levels is transferred through gigantic trusses to a steel-framed office grid. The long spans in the shopping concourse fell outside the higher bulk of the building. “Each use had to have its own lobby presence,” added Abadan. “People expect that sense of exclusivity.” Those seven lobbies also enliven Columbus Circle, an important urban open space, 24 hours a day. Skylobbies would probably have been more space efficient, but tenants and owners who pay top dollar do not want to transfer, Abadan said. One hundred-thirty elevators serve the building.

A number of towers on the boards express their mixed-use nature explicitly. Renzo Piano’s London Bridge Tower stacks a narrow spire of apartments above a hotel and a thick base for offices and retail, as well as a revamped rail station. The functions meet at dramatic skylobbies—visible from outside. Form elegantly transforms as it rises through different functions in SOM’s Jinling tower.

Towers as lab benches for sustainability

The skyscraper has always been used to prove new technology that then spreads more widely throughout the building industry. The greatest focus recently has been on energy conservation, which can seem quixotic because everything about skyscrapers seems to demand conservation compromises: If you introduce more glass to use less electric lighting, you add heat gain. If you build shallower floors or add secondary glass walls for insulation you add a great deal not only to construction cost but to material used in construction. The narrow floor plates used often in northern Europe look inefficient because of the relative size of cores and structure.

But the penalties for pursuing conservation are rapidly dwindling. Holistic analysis of “building physics” (now common in Europe) is displacing the traditional mechanical-engineering focus on cubic feet of air moved per minute. Advanced designs use the buoyancy effects of air in double curtain walls. They exploit diurnal temperature swings and manipulate building form both to encourage natural ventilation and to reduce heat gain.

Advanced distributed-air systems reduce ductwork needs and shaftways, according to Matthias Schuler, of Transsolar, a pioneer in the use of nonmechanical means to achieve user comfort. This delivers lower floor-to-floor heights for the same ceiling height and gets more usable square feet per floor. Like many foreign tall-building innovators (Schuler is based in Stuttgart), he is optimistic enough about America jumping on the innovation bandwagon to open a New York office. By separating dehumidifying from ventilating and cooling, Schuler argues, cooling energy can be dramatically reduced even in the sealed buildings that prevail in hot, humid climates where the northern European natural-ventilation techniques don’t work. The tilt of units in the “shingled” curtainwall of a Murphy/Jahn tower he has collaborated on leaves space for fresh-air vents in soffits on each floor. If necessary, the air can be cooled or heated using miniaturized fan-coil units tucked beneath the floor. This “breathable” skin saves energy and simplifies and reduces the building’s mechanical requirements. Jean Nouvel takes solar protection yet another step in the Agbar tower in Barcelona (Shown right, top).

Structural advances, such as the diagonal external grids that are appearing more frequently on new designs, also reduce core sizes and column needs, increasing usable floor area. For very tall buildings, cores laced with trusses combined with massive outrigger structures liberate tower form and allow more usable space. They have become more common since their early use by Thornton-Tomasetti and Cesar Pelli in Malaysia’s 1998 Petronas towers. They figure in a number of designs selected by Guy Nordenson and Terence Riley for the recent “Tall Buildings” exhibition at the Museum of Modern Art. (There is a catalog published by the museum.)

Do skyscrapers still make sense?

“I don’t believe the challenges are in making towers bigger, but more livable,” says Craig Schwitter, a structural engineer with Büro Happold in New York. Indeed a great deal of versatility can economically be incorporated into much lower towers. Concrete framing, for example, can permit geothermal cooling through the slab, according to Schuler, a scheme that may reduce cooling costs to almost nothing. With American companies generally looking to drive occupancy costs lower (and with first-costs remaining paramount), America isn’t ready yet to move to the forefront of tall-building innovation. The terror attacks three years ago—of all things—may have galvanized change in the slow-moving sensibilities of the real-estate industry. “Buildings can’t be seen as adversarial,” explained Schwitter. He argues that wary tenants and staff become more comfortable with working on high floors when they incorporate green space, when they minimize discomfort and make the most of daylight and fresh air