Green grows up... and up and up and up
Sustainable high-rises are sprouting from Manhattan’s bedrock.
By Deborah Snoonian, P.E.
 
   


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photo © Jock Pottle/Esto

New York Times Tower
Among the green features of the building are a solar screen of ceramic rods, automated skylights, onsite cogeneration, and a courtyard garden. The lowest levels of the building offer full transparency, with views out and in. Extensive lighting studies were performed at a full scale mock-up, which was also used to test furniture layouts and the constructability of the facade. The tower’s high-tech lighting and shading system will be commissioned at the mock up before installation.


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image courtesy dbox

One Bryant Park
Rainwater will be collected, stored in four different locations, and reused for toilet flushing and as makeup for the cooling towers. Raised floors for cabling and underfloor air distribution eliminates ductwork and improves indoor air quality. The podium entry on Sixth Avenue will feature photovoltaics. The building’s angular, faceted form was inspired by Bryant Park’s Crystal Palace of 1853, the first glass-and-steel building in America. One triangular “face” of the building will be double-glazed to vent excess heat.


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image courtesy Flack + Kurtz

Hearst Tower
When finished, the building will house all of Hearst’s magazine-publishing operations in New York. Irregular corners and angles of the structural diagrid posed a challenge to engineers designing the HVAC system, who used computational fluid dynamics to analyze airflow patterns on each floor. In a twist on double-walled construction, the spaces between the new structure and the preserved facade as well as a neighboring apartment building will be used to move and vent air. Rainwater will also be collected and reused onsite for irrigation and as cooling tower makeup.


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Freedom Tower
Battle McCarthy is designing an integrated wind-turbine farm to top the world’s most scrutinized skyscraper. Preliminary estimates indicate the turbines could provide as much as 10 to 15 percent of the building’s energy demand. Other sustainable amenities are typical of those in other high-rises: rainwater capture and reuse, use of recycled content and low-VOC building materials, and recycling of debris during construction.


Image courtesy Fox & Fowle

The Helena
Fox & Fowle Architects’s 580-unit tower sits on the Hudson River at West 57th Street, an area undergoing explosive growth in residential construction. The building will be the first voluntarily sustainable residential high-rise in New York, but others planned throughout the city will soon follow. It is expected to achieve a LEED gold rating, with features including a green roof and gray-water recycling.

Tall buildings are getting greener. Or green buildings are getting taller. Either way you slice it, the sustainability movement in the U.S. has gone large-scale and skyward, and nowhere is this more apparent than in New York City. By the end of this decade, several green high-rises now planned or under construction will pepper the Manhattan skyline, including a headquarters for the nation’s leading newspaper, the Freedom Tower, apartment buildings, and office towers for a financial institution and a major publisher.

Why the surge? New York owners and developers say they’ve discussed green design for years, but no one wanted to be the first to take the plunge—that is, until the Durst Organization hired Fox & Fowle Architects to design the Condé Nast Building at Four Times Square. Within a year’s time from 1999 to 2000, Four Times Square opened, Battery Park City’s environmental guidelines for residential construction were passed, and the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) certification program was established. “Those three events changed everything,” says one developer who wished to remain anonymous. “Before that, we said, ‘Why bother?’ No one understood green design or what its advantages were. But after Four Times Square, everyone thought, ‘We can do that too.’ And LEED gave us a blueprint for understanding how to get there.”

The projects underway involve committed clients who’ve hired architects capable of leading multidisciplinary and often international teams through the confusing choreography of standards, guidelines, and best practices for sustainable design. Though the technologies and strategies they employ aren’t always new, many are rare in tall buildings in the U.S.—a situation that will change as more cities embrace density and draft their own sustainability principles.

The Grey Lady’s green makeover
When Renzo Piano Building Workshop and Fox & Fowle Architects were chosen as the winning team for the new headquarters of the New York Times, critics swooned over its facade of ultra-clear glass shaded by a scrim of white ceramic tubes. As owners, though, the Times was concerned about glare and heat gain. Would eye-strained reporters literally sweat over their deadlines as they cranked the air-conditioning to budget-busting levels? In late 2002, lighting consultants SBLD Studios and interior architect Gensler were already evaluating lighting and shading systems when David Thurm, vice president of facilities for the Times, happened upon a technical paper written by Stephen Selkowitz, a lighting expert and head of the building technologies department at the Lawrence Berkeley National Laboratory in California.

So began a one-of-a-kind research project. The Times design team met with Berkeley Lab researchers, who recommended an integrated facade management system of dimmable lights and mechanized shades that would respond to the sun’s angle and intensity. Just weeks later, the Times decided to build a freestanding mock-up of the tower [RECORD, March 2004, page 169] that would let them test real-world conditions for such a system, and by mid-June, Berkeley Lab secured a grant from the New York State Energy Research Development Authority (NYSERDA) to collect data they’d need to design it. By the first day of winter 2003—less than a year since the initial meeting—the mock-up stood complete and over 100 sensors began collecting data for a solstice-to-solstice study that allowed researchers to model light conditions year-round. The zones and control schemes were tweaked continually as data were collected. “We didn’t want fixtures going on and off, or shades going up and down constantly,” says firm principal Bruce S. Fowle, FAIA. The study showed that enough daylight penetrated the 44-foot perimeter zone of the building to permit lights in that area to be dimmed, if not turned off entirely, and lighting energy savings in winter ranged from 10 to 70 percent.

The design team issued solicitations based on detailed performance specifications written during the study. Just last month, Mecho Shade, Lutron, and Zumtobel were selected to provide shades, dimmable ballasts and controls, and custom fixtures, respectively. A second NYSERDA grant will allow these suppliers to commission their systems in the mock-up before installation. “This will reduce the chance of poor performance and cost overruns,” says Thurm, problems that have plagued wider adoption of these technologies.

The design also calls for underfloor air distribution (UFAD) on the floors occupied by the Times. Though it’s known to improve indoor air quality, UFAD hasn’t been used much in U.S. high-rises. “There’s a false perception that raised floors sound cheap,” says Fowle. “That may have been true years ago, but not anymore.” To plan its implementation, the Times gathered nearly 40 architects, engineers, and consultants involved with the new tower and a building for another paper they own, the Sarasota Herald-Tribune. “We worked out construction sequencing and other details that would have been difficult to do in one-on-one meetings,” including measures to keep the plenums clean, says Glenn Hughes, director of construction for the Times.

A bank invests in efficiency
Just a few blocks east of where the Times broke ground in August, another glazed tower began construction. Designed by Cook + Fox Architects, One Bryant Park is being codeveloped by its main tenant, Bank of America, and the Durst Organization. The project team is gunning for LEED platinum—a first for an office high-rise.

Though European architects have turned to double-walled glazing systems for efficiency, such a system wouldn’t have worked here because of New York’s hot, humid summers, says partner Robert Fox, AIA. Still, one “face” of the building, which looks south toward Bryant Park, will be double-glazed to prevent heat gain, and floor-to-ceiling glass will be fritted at the top and bottom for interior comfort but left clear in the middle to preserve views.

A variety of energy-saving technologies are planned, including an onsite 4.6-megawatt cogeneration system, geothermal heating and cooling, and building-integrated photovoltaics (BIPVs) installed in three places—atop a glass roof that floats over the subway entrance, along the entry pavilion on the southeast corner, and on spandrels that support a 10-story notch on the eastern facade. Though they won’t produce large amounts of electricity, “we used BIPVs near the ground so people could see them and learn the importance of renewable energy,” says partner Richard Cook.

Fox says sustainable design has taken leaps and bounds in the years since he and former partner Fowle designed the Condé Nast Building and helped draft Battery Park City’s guidelines. “Back then the architects and owners really led the process, but now we’re used to teaming up with engineers and consultants earlier on. And for Bank of America, we challenged ourselves to make the best use of everything that’s available for free: air, sunlight, rainfall.”

As in the Times building, UFAD will be used on floors occupied by Bank of America. Other features include a one-acre planted roof on the podium and an air filtration system that removes 95 percent of particulates, compared to 35 percent for most buildings and 85 percent at Four Times Square.

A publisher puts its magazines under one roof
In the mid-1990s the Hearst Corporation, whose titles include magazines like Esquire and Cosmopolitan, began looking at its real-estate operations in New York with an eye toward consolidation. After analyzing the rental market and crunching the numbers, they decided to build their own space—sustainably. “Buildings have such a huge impact on the environment and health, so having our own green building was a way to recognize this and put our employees first,” says Brian Schwagerl, director of real estate and facilities planning for Hearst. Foster and Partners won the commission for its first major work in the U.S. With his usual technical rigor, Lord Norman Foster designed a glazed tower that’s being inserted—where else?—into the shell of the original 1927 Hearst Building, to which a planned high-rise was never added.

The building’s 856,000 square feet will contain a skylit atrium with a cafeteria and auditorium, a water feature (still under consideration) fed by harvested rainwater that would provide cooling in summertime and help with humidification, and space for all of Hearst’s magazine employees in New York. The project is expected to garner the first LEED gold rating for a commercial office tower in New York State.

After analyzing several HVAC options, including UFAD, engineers Flack + Kurtz opted for slab-integrated heating and cooling with low-temperature air. Temperatures can be controlled from stations located on each floor, and in lieu of floor-by-floor mechanical rooms, central air handling units will be housed on the 28th floor to make it easier to flush them with outside air. Engineer Paul Reitz says they found the dips and angles of the diagrid a serious challenge in analyzing the system’s performance. “We relied heavily on computational fluid dynamics (CFD) to determine how air would move on each floor,” he says. “Without CFD, the entire system would have been guesswork—and we could have guessed wrong.” CFD also enabled clever use of the building’s tight site; the space between the preserved six-story facade and the new structure, as well as between the structure and the apartment high-rise to its west, are being used as plenums to move and vent air.

Reliance on such high-tech analysis is increasingly common in sustainable design, and this project has benefitted from a partnership between a world-class architect fluent in technology and an engineering firm that’s been intimately involved with the sustainable-design movement in New York City through projects and standards-setting. “I’m hard-pressed to find a firm that cares about the details more than they do,” says Reitz of Foster’s staff, who express the same sentiment about their partners. That trust has proven necessary to achieve any measure of success with green building.

A tower powered by wind
If all goes as planned, the most scrutinized high-rise of our time will be the first in the world to harvest wind. Last year, London engineering firm Battle McCarthy was tapped to design an integrated wind-turbine system for the Freedom Tower. The firm has worked on similar schemes for other buildings, but none have been realized.

Though turbines are a well-developed technology, concerns about noise, vibration, and safety have kept them off buildings in densely-populated areas. That will change. “Wind turbines make sense particularly for tall buildings, where you don’t have to pay for the structure to put them up,” says Guy Battle, principal of Battle McCarthy. Engineers are finding ways to make them quieter, he says, and despite common perceptions, there’s little risk that turbine blades will fly off or dismember birds in midflight.

It’s unclear whether architect Skidmore, Owings & Merrill will pursue LEED certification for the Freedom Tower, but the firm maintains that LEED criteria are guiding the design. More green towers can be expected to rise in lower Manhattan, too: Following Battery Park City’s lead, sustainable design guidelines have been drafted, and developer Silverstein Properties is seeking a new type of LEED certification for the exterior structure of Seven World Trade Center, slated to open in 2005. The core-and-shell LEED program was established in 2003 to encourage sustainability for developer projects built on spec, a market several times larger than that of owner-occupied buildings. A companion program, LEED for Commercial Interiors, will allow tenant fit-outs to be certified as well.

Greening the sky-high home
It was just west of the WTC site, in Battery Park City, where sustainability took root. Last year, the Solaire became the first residential high-rise completed under the neighborhood’s green guidelines; now a second tower, also designed by Cesar Pelli & Associates, is under construction at 211 Murray Street. The new building will share a blackwater treatment system located in the Solaire’s basement. Treated water from both buildings will be used as makeup water for cooling towers and will feed clean water to a nearby park.

Similar projects are underway in Battery Park City, and now neighborhoods like midtown and Hell’s Kitchen are building green residential towers even in the absence of mandates. The first to open will be The Helena, a 37-story tower on West 57th Street, designed by Fox & Fowle and expected to achieve LEED gold.

Green residential high-rises might be even hotter than the commercial market in New York. “There are bigger opportunities for implementing sustainability in residential tall buildings,” says Gary Pomeranz, senior vice president of Flack + Kurtz. “People don’t interview for a job and wonder, ‘What’s the air quality like in here?’ But when they’re looking for an apartment, they want clean air, clean water—and they’ll pay extra for those amenities.” That’s proved true at the Solaire, where rents have averaged about 10 percent higher than at conventional buildings.

Beyond ratings and ribbon-cuttings
Accolades aside, the true test of sustainability will begin when the dust settles at these construction sites. Any building can be operated inefficiently, and this is especially true of large structures with complex systems, multiple tenants, and mixed uses. Each of these towers will be fully commissioned before opening to head off operating problems, and developers like the Durst Organization have even been successful at securing grant funds from NYSERDA and other agencies to periodically test and commission their existing buildings. LEED also aims to correct this situation by requiring projects to be reevaluated after five years to maintain their rating.

Though even American architects agree they lost ground to designers bound by higher energy prices, “the U.S. has been taking cues from high-rises in Europe and Asia, particularly in curtain-wall design, for efficiency,” says Paul Katz, principal at Kohn Pedersen Fox in New York, which is building multiple high-rises in Shanghai and Hong Kong. Future U.S. projects will see even more melding of architecture and engineering to meet sustainability goals through formal means, and the most innovative examples might occur outside New York. “The city’s zoning laws are based so much on the street grid that they’re totally contrary to green design. They almost predetermine form and orientation,” says Fowle.

But for now, the Big Apple’s green towers represent the best in U.S. practice. And they point up the growing influence of LEED and local sustainability mandates, despite the inevitable limitations and flaws of such criteria. Peer pressure helps too. As one Manhattan developer put it, “It would have been nice to have been the first to build this way, but that’s okay—we’ll just set higher goals the next time.” Exactly.