...and 48 for the core. Though the building is designed to be 58% more efficient than a code-compliant building in China, it will not be the net-zero-energy building that its architect-engineer envisioned.

“We don’t have enough data to give developers the confidence that [the net-zero energy systems] work,” said Russell Gilchrist, director of technical architecture in the Chicago office of Skidmore, Owings & Merrill.

The new, second-tallest building in the U.S., which is seeking LEED Gold certification, is virtually complete. The 1,362-ft Trump International Hotel and Tower opened in phases beginning last year.

Trump and all other supertall buildings are trumped by the 800-m-plus Burj Dubai. Mohamed Ali Alabbar, chairman of developer Emaar Properties PJSC, Dubai, says the Burj will open on Dec. 2 after more than a year of delays.

In a sea of tall-building boosters, both Alabbar and Andy Weiss, executive vice president for the Trump Organization, New York City, said supertall building development is not for the feint of heart. Weiss advised developers to prepare for a time-consuming and costly entitlement and zoning process, pay attention to quality so the building can become an icon and begin with a large, centrally located site.

Financing for a supertall building can be another headache because of the need for a large lender, Weiss said. If there are multiple uses, be prepared for a complex design and construction process. “Use firms with track records,” Weiss advised.

With Trump International, the firm started a trend in the U.S. for phased occupancy of supertall buildings. “To have 30 stories of finished building sitting idle is a major drag” on a project, said Weiss.

But phased occupancy brings its own logistical headaches, which need to be accommodated from Day One. “It’s like stacking a series of independent and fully functional buildings one atop the other,” Weiss said. “Phased occupancy permeates the entire design process and every construction element.”

Richard Hanson, founder of Mesa Development, Chicago, knows all the pressures of completing a supertall building in a recession. Condominium closings began last month on his 72-story Legacy at Millennium Park, in the Loop, which achieved a presale status of nearly 90%. The closing pace has averaged one per day. But with real estate values down, it feels as if “you are continually reselling the condos,” he said.

For now, his optimism is lagging. “There’s no debt anywhere in the U.S.,” he said. “You can’t borrow money.”

Still, Hanson is upbeat about the future. “It will take some time before the housing market stabilizes, but we look forward to building tall buildings in several major metropolitan areas,” he said.

Weiss is more discouraged. “The landscape is littered with grandiose plans for buildings not completed or not even started,” he said. “You have to be able to predict the cycles in real estate, trying to complete the project within a cycle. Unfortunately, I don’t think many of us can.”