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 For the country's first sustainable residential tower, green design choices are worth their weight in gold. October 2001
The green building movement may be more obviously concerned with economics than most previous architecture trends. It challenges architects to understand the lifetime costs, monetary and otherwise, of occupying a building. And though most green buildings attack this challenge with glass and landscaping, they needn't. Green design is more about how a building works than how it presents itself. Pelli, New York principal of Cesar Pelli & Associates, says energy-efficient technology is evolving faster than architectural dogma. "The information necessary to make decisions is different from what it was two years ago," he says. And this information remains exotic to most construction trades. So green design must justify pricey materials and contractors, which leaves little room for show-offy science. It also makes having patrons extremely convenient. The affable, bespectacled Pelli had a big one: the Battery Park City Authority (BPCA), created by New York State to develop a 92-acre landfill between Manhattan's financial district and the Hudson River. Pelli's father, Cesar, designed the glassy World Financial Center there in the early 1980s. He shaped the towers according to classicist design guidelines but famously clad them in thin walls to keep costs realistic. In 1999 New York governor George Pataki initiated legislation to provide tax credits for green architecture. The BPCA soon re-quested proposals for a flagship tower that would use natural light and materials and consume less energy than New York's standard buildings. "We've been given an orientation, a volume, a height, a shape," says Pelli, who won the bid. "We've been mandated a brick building." Just as his father had with a different mandate, Pelli set out to interpret guidelines and economic limits with his own stamp. As Pelli's team assembled its bid, a rule emerged. Steep expenses that made the building's air and lighting systems healthier became investments worthy of serious study. "Indoor air quality was a very high priority," Pelli says. "We had to allocate more space to mechanical systems." Theatrics, conversely, became costly indulgences. Other applicants tried them anyway--one proposed a "living machine," which filters and recirculates wastewater in a series of landscaped pools under hanging plants. This invention, although lovely, ignored the site's cost and space limits. Pelli respected those limits and won the contract by fine-tuning windows, power systems, and walls. His facade celebrates efficiency. Windows lock into slender casements, reducing heat loss and repelling pollutants from the interior air. The coated glass retains light while blocking excess heat more aggressively than guidelines require. Plants on the roof and at a setback halfway up expel summer heat instead of absorbing it. Photovoltaic cells in the building's skin generate electricity from sunlight, independent of Manhattan's power grid. Pelli has arranged them into a broad stripe that surrounds the doorway, heralding the future. But the building's real mission plays out within its walls. "No other rental that I know of has dedicated fresh air supply to all apartments," boasts developer Russell Albanese, comparing the atmospherics to a luxury hotel's. Motion sensors control hallway lighting. Digital thermostats help residents consume only the heat they need. But cutting a building's consumption demands more brains and data. Even a wall, explains environmental consultant Asher Derman, becomes a physics problem for a host of contractors. Pelli and colleague David Hess huddled weekly with Albanese, Derman, and some 16 others. Derman says the team had to align several professions. Bricklayers, stonecutters, glass installers, and other artisans--some more mulish than others--all had to learn new roles. "Trade unions can affect the degree to which a client can introduce novelty," Derman says tactfully. He should know: his firm, Green October, consulted to three 20 River Terrace bidders. Derman's busy schedule highlights a major cost factor: pickings among green vendors can be slim. Scarce supplies forced Pelli's team to keep some clumsy innovations while scrapping others. For example, the team wanted to place a device on the roof to rescue lost heat. But nobody offered models small enough to satisfy zoning laws. Meanwhile, green guidelines required space for an electricity-generating fuel cell--whose installation Pelli wants to delay until more efficient models arrive in the next few years. Green architects often have to design buildings to fit equipment rather than vice versa. "The manufacturers make what the manufacturers make," says Carlton Brown of Full Spectrum Building and Development, a Harlem developer that advised Pelli on environmental technology. "We found ourselves on the cusp," Pelli shrugs. When guidelines devote some 700 square feet to a future appliance, you must wring gains from basic places. So while some heat escapes from the roof, central fans will manage temperatures at variable speeds to save energy. Pelli's team also spent months studying how apartments seep air before deciding to reconstruct the walls. "Think of that eighteen-inch layer [inside a wall]," Pelli says. "The amount of time spent trying to optimize it was one of the most interesting aspects of the job." Most developers fill walls with insulation that allows heat and cooling to leak from wall joints, wasting lots of energy. Pelli seals his walls with a solid barrier. Most buildings also run air-conditioning through leaky sleeves in walls. Pelli runs fresh air--cooled or heated by a natural-gas-powered HVAC system--through central ducts. Albanese predicts that the building will use 35 percent less energy and demand 67 percent lower peak electricity than standard buildings. The team chose to recycle all the building's water--sans living machine. A basement plant collects wastewater, treats it, and returns it as clean water to the building's toilets and cooling tower. This also exceeds guidelines, which require only reuse of bathwater. The plant should treat enough water to service the entire building and irrigate Teardrop Park, the mini-glen that will go behind it. This process, while kind to the water table, will be invisible to tenants and guests. "That's the public-relations tragedy of green building design," Derman says. But such invisibility suits a green agenda. Battery Park City Authority president Tim Carey, whose crinkly eyes brighten when he inspects the master-plan models lining his office, says Pataki's mission involves making green design a wholly plausible urban style. Ideas like the living machine didn't fit in because they would only work on jumbo-size lots. "We felt that it was important to keep it in its footprint," Carey says, "so that you could pick it up and put it down in Albany or Buffalo or Los Angeles." Green buildings derive identity from feeling natural. They should reflect the changes in light and temperature outside and fit unambiguously into their surroundings. This focus on keeping buildings healthy and familiar, rather than ecologically strident, may be peculiarly American. "There is a slightly narrower acceptable range of comfort for most Americans," Pelli says. So "passive" systems, which rely heavily on natural light and temperature, are more tenable in Europe than here. "People want hot showers and cold beers," says Randy Croxton of green boutique Croxton Collaborative Architects, quoting influential physicist Amory Lovins. Pelli's design indeed shows how high-tech engineering can serve high-rent aesthetics. He stretched the glass wall as far as the design guidelines allowed, so the middle and upper floors can shimmer in the sun. The photovoltaic stripe will also shine. Pelli raves about photovoltaics' "peak energy harvest" on summer afternoons, when the power grid becomes costly. But according to Derman, photovoltaic panels perform most efficiently at angles, rather than in vertical stacks. The stripe provides symbolic flourish, making up for suboptimal stacks with extra cells. Likewise, Pelli adds a decorative green trellis on the doorway below the required vegetated roofs. The roofs meaningfully improve temperature control ("We won't build this way anymore!" Carey enthuses, waving over the black roofs below his office window), but the trellis mostly looks pretty. Pelli, though, had little latitude to make purely cosmetic choices. More likely, the photovoltaics set a prototype for future high-rise economics. "We knew we weren't saving money," Albanese says. "It would have been cheaper to stick everything on the roof." But as cells become more common, he expects them to appear in more facades. Hess says the stripe aims to establish the shiny cells as "just another building material." At the building's groundbreaking ceremony, Pataki struck a similar theme. "We will have buildings that reflect our environment rather than isolating residents from it," he declared. As 20 River Terrace joins Manhattan's skyline, Pelli hopes future developers will copy its wall and wastewater systems for efficiency's sake. His focus remains, rightly, on the inside. For all the building's beauty, its ecological and economic costs will determine how quickly its ideas spread. Alec Appelbaum writes about business, cultural, and environmental issues from New York City. |
