Two iconic Manhattan skyscrapers have emerged from major renovations with sharply reduced carbon footprints, making them beacons of New York's evolving "green skyline." But the two projects could hardly be more different. The United Nations Secretariat building, designed by a team of architects including Oscar Niemeyer and Le Corbusier, was completed in 1952. After a gut renovation, the 39-story building reopened this year. "We tracked the LEED criteria, as well as guidelines from Japan and Great Britain and Australia, which in some cases are more stringent," says Michael Adlerstein, Assistant Secretary-General and Executive Director of the U.N. Capital Master Plan. "We wanted to restore the building in a way that, if we were to be evaluated, would meet the standards of what the world expects."
Courtesy of Green Mountain Energy Company
By contrast, Jones Lang LaSalle (JLL), which managed the $550 million renovation of the Empire State Building, has "a close relationship with the USGBC," says Dana Robbins Schneider, JLL's senior vice president in charge of Energy and Sustainability Services for the Northeast region, who worked to ensure that the building would receive LEED Gold status.
The 102-story Empire State Building, designed by Shreve, Lamb and Harmon and completed in 1931, was already scheduled for renovation in 2008 when the nonprofit Clinton Climate Initiative approached Anthony Malkin about ways to reduce its carbon footprint. (Malkin and his father lead the investors who own the building.) One of the goals of the renovation was "to prove the economic viability of a deep energy retrofit," says Schneider. She and her team began examining dozens of strategies; they eventually came up with a plan they projected would reduce energy use by 38 percent, paying for itself within three years. "For most owners, an energy project has to pay for itself within three or four years through reduced energy costs to be considered a good investment," says Schneider. The strategies included reconstructing each of the building's 6,514 double-hung windows, reusing the existing glass, sash and trim, and adding a low-emissivity (low-E) film suspended between the two panes of glass to more than double the original R-2.0 center-of-glass thermal value. The remanufacturing was carried out on-site, to avoid the costs, monetary and environmental, of shipping. In fact, Schneider says, the energy savings have exceeded the projected 38 percent in the first two years of post-renovation operation. As part of JLL's contract with Malkin, she says, "we perform intensive measurement and verification." And the performance will only get better as new tenants move into the building—their leases require them to meet strict performance guidelines, and Schneider works with them to select daylight dimming, variable-volume air conditioning, and other green systems. Not only is information shared among tenants, Schneider says, but it is shared publicly, so owners around the world can replicate the results.
One of the projects rejected initially as not cost-effective involved replacing the incandescent bulbs that illuminate the building's famous spire. Schneider's team continued to monitor the available technology, and last year it decided that the cost of LEDs had fallen to the level where the project made economic sense. Every visitor to New York can see the results. LEDs are twice as efficient as the previous generation of lights and make it possible to change the appearance of the building's legendary light shows instantly.
Rather than having to satisfy investors, the U.N. answers to 193 member states. But the Secretariat building was so dilapidated that virtually everyone could see the need for drastic measures. The building's original, 1/8-inch-thick glass provided practically no insulation. Window-washers described a zone of cool air around the building on the hottest days, and curtains moved in the breezes even with the windows closed. Over the years, the U.N. had added reflective film to the glass, to reduce heat absorption and glare, but the film just made the glass look dirty.
Adlerstein's public information officer, Werner Schmidt, gave lots of what Adlerstein calls "dirty tours"—designed to demonstrate how badly the structure needed renovation. But it wasn't just the $150 million cost of the Secretariat renovation (part of a $2 billion refurbishment of the entire U.N. campus) that required selling. The original Secretariat had hundreds of private offices on its 39 floors. Adlerstein was determined that the renovated building would have an open plan to reduce energy consumption. In addition to improving air flow, it requires less ductwork and fewer sprinkler heads. But, not surprisingly, many workers didn't want to lose their private offices.
Adlerstein's proposal was eventually endorsed by Secretary General Ban Ki-moon—which, he says, "is the only way these things happen." The project was green from the start: according to Adlerstein, as the building's facades and interiors were disassembled, 95 percent of the material taken from the site was recycled for other purposes. "All the aluminum, all the glass from the curtain walls, the interior walls—the only material that didn't get recycled was the asbestos," he says. Skanska, the general contractor, "made the subcontractors deliver receipts from the proper dumps for materials taken from the site."
Once the building was gutted, a two-year process of replacing the facades began. The new curtain walls are double-glazed units installed with thermal breaks. Behind the glass is a "daylight-harvesting system"—perforated venetian blinds that open and close automatically as the sun moves from one side of the building to the other. The other big move was replacing the building's old steam chillers with efficient electric chillers.
Overall, the building uses about 50 percent less energy (a mix of electric, gas, oil, and steam) than it did before the renovation and emits about 45 percent less carbon, says Adlerstein, citing the work of consultants who are monitoring the Secretariat's performance. And there are other green achievements, including a reduction in fresh water use of nearly 50 percent, he says, largely from "being more clever about toilets and sinks and urinals."
But in each case, the greenest move may have been renovation itself. True, razing either the U.N. or the Empire State Building was unthinkable (though the U.N. is not subject to landmark laws). "If you build a new building, even if it's a very green building," says Adlerstein, "you've thrown away the energy embodied in the previous construction."