News
11.19.2008
Stepping Up
Refining the next generation of green skyscrapers: From 4 Times Square to One Bryant Park, The Durst Organization has profited from a growing awareness of the virtues of green design, along with great strides in energy-efficient technology. Aaron Seward talks to the major players.
One Bryant Park breaks new ground, as in the use of underfloor ventilation throughout the entire height of the structure.
Courtesy Cook+Fox

When 4 Times Square was completed in 1999, the project was touted as the harbinger of a new era of environmental responsibility in the design of tall buildings. But for a while longer, skyscrapers in New York City continued to be designed and constructed in more or less the traditional manner. The games of one-upmanship that would have indicated a dedicated consensus of green builders did not immediately materialize. “When we built 4 Times Square, we were creating a template of a way of building that people would have to follow,” Douglas Durst, president of The Durst Organization, developer of 4 Times Square, told AN. “Not many people did. It takes a while to see how successful and adaptable it is, for it to spread to other people’s projects.”

It took some time for the benefits of green design for tall buildings to be better understood, for the industry to accumulate hard data linking healthy, daylight-filled offices to higher worker productivity, and greater energy efficiency to lower electricity bills. But the green building boom didn’t begin in earnest until developers realized that they could charge higher rents for spaces that adhered to greater levels of sustainability. The trend first became apparent in the city when Larry Silverstein decided to seek LEED Gold for 7 World Trade Center, and Hearst did the same for its new tower. “It was disappointing that it took so long, but a lot of people in the industry thought it was a quacky idea,” said Bruce Fowle, partner of FXFowle, designer of 4 Times Square. “Now it’s a marketing tool.” The change in attitude can be seen quite clearly in the example of the New York Times Building. While the project took great strides in energy efficiency and usage of daylight, Forest City Ratner and the New York Times Company opted not to pursue LEED. “In 2004 when we had to make the decision [to pursue LEED], it was still a fairly new idea, and they didn’t feel that they had to put a label on it,” continued Fowle. “In my last pitch to them I told them they were going to spend the rest of their life explaining why they didn’t go for LEED rating. And that’s what’s happening.”


David Sundberg/Esto


BERNSTEIN ASSOCIATES PHOTOGRAPHERS

Top: When 4 Times Square was completed in 1999, it was heralded as the first green skyscraper. Above: Ten years later, One Bryant Park will become the first LEED Platinum office building in New York City.
 
 

The LEED system was still under development when 4 Times Square was designed and built, so there is no reliable way to quantify just how it measures up to the certified office towers now up and running in the city. Some experts think, however, that most of the new green skyscrapers haven’t gone far enough in pushing the envelope on sustainable design. That honor has been reserved for Durst’s latest project, the Bank of America Tower at One Bryant Park, which is currently nearing completion. Once finished, the building will seek a LEED Platinum rating. “It’s a pretty easy comparison to go from 4 Times Square to One Bryant,” Serge Appel of Cook + Fox, designer of One Bryant, told AN. “At One, Durst took what they learned at 4 and went on from there. In terms of green building, 4 might be at 25 on a scale of 1 to 100, while One’s a 75. There’s more infrastructure, more thinking. It’s the next generation.”

So what did they learn? What defines the next generation of green skyscrapers? First, One abandoned some of 4’s more showy energy-producing features, namely the building-integrated photovoltaics. In the final analysis, the solar cells generated very little energy, only about one percent of the base building needs. Even at the current state of the technology, photovoltaics did not prove feasible for a tall building that remains in shadow half of the day. Instead, the designers at One opted for a 4.5-megawatt, gas-fired cogeneration plant, which recycles waste heat from the engine for heating and to power absorption chillers for cooling. And while the plant will not cover the building’s overall energy usage, producing energy onsite is more efficient than pulling it off the grid, which is only about 50 percent efficient.

The interior’s environmental air quality was improved at One with a better filter. It removes 95 percent of particulates, while 4’s removed around 85 percent. Not a huge jump, but the real advance in this area is the usage of underfloor displacement ventilation, while 4 uses a traditional overhead delivery system. The underfloor method was used in the New York Times Building, but only in the newspaper’s half of the structure. One will be the first project to use it throughout. It keeps the interior healthier by creating successive air chimneys on each floor, which avoid mixing exhaust air, which rises to the ceiling, with fresh air. The method also requires less energy for air conditioning, since it only conditions from the floor to the tops of people’s heads, rather than all the way from the ceiling to the floor.

The building envelopes also differ. While 4 can boast of greater insulation values, as a large portion of its exterior is masonry, at One, the designers decided to go with an all-glass system. The loss in energy savings is balanced out by the fact that a completely transparent facade brings more daylight into the interior, which, when combined with daylight-dimming light fixtures, drastically cuts down on the power needed for lighting—the greatest energy consumer for buildings of this type. While 4 employed similar strategies, few if any tenants actually implemented daylight-dimming fixtures and many fitted out their spaces with perimeter walls, which cut down on daylight transmission.

In addition to the savings in lighting energy usage, the designers of One picked an all-glass system to create a more daylight-filled environment for the workers. And the glass curtain wall at One does go as far as current technology allows to insulate the building: It is a thermally broken system, which prevents heat exchange between exterior and interior mullions, and the low-e coating and ceramic fritting on the glass panels significantly cut down on heat loading from the sun.

One takes a definite lead in its conservation and reuse of water, employing systems that were not available at the time of 4. The entire building is outfitted with waterless urinals and systems for gray water recycling as well as rain and ground water collection. Overall, the building should save 55 percent of water usage over a traditional building, easing effluence into the sewer system.

Both projects distinguished themselves by adhering to green practices, though it is difficult to compare the two projects in this regard as no metric existed at the time of 4 to let the designers know just how green they were being. Materials were sourced locally even when a premium had to be paid. At One, countertops are made from Icestone, a recycled glass product manufactured in the Brooklyn Navy Yard, which cost more than Italian marble. Construction components were reused on site. The big item in this regard at One was wire spools—contemporary office buildings have a lot of wiring. The construction teams were coached on green building practices and monitored by a third party.

But while it appears that One has exceeded 4 in just about every green check box on the list, it’s hard to regard it as the trailblazer that the previous building was. “There’s nothing in One that is experimental,” said Appel. “Everything has a legitimate payback period that a developer can justify.” Rather, it seems that the steps taken at One should be taken these days as a matter of course. The next generation of green skyscrapers, then, must lie elsewhere. “We need to be thinking beyond LEED,” said Fowle. “How can we do zero carbon and zero net energy buildings? Buildings that are not just better, but that have a positive effect on the environment, as opposed to a less negative effect.”

Aaron Seward

Aaron Seward is an associate editor at AN