Kroon Hall Rises

F&ES’ New Ultragreen Home

Photos by Robert Benson Photography
Illustrations by Gregory Nemec

A casual visitor to the new home of the Yale School of Forestry & Environmental Studies might not consider it radically different from any other building at Yale. At first glance, Kroon Hall is strikingly simple—a modernist blend of a cathedral nave and a Connecticut barn, just 57 feet wide, with high barrel-vaulted gable ends, set back from Prospect Street and running 218 feet east into the heart of Science Hill.

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Robert Benson Photography

But from the start, more than a decade ago, proponents of the building set out to achieve an unconventional, even audacious, agenda here, focused on building social capital, breaking with the past and speaking to the future of environmentalism. They wanted a healthy place to study and work, of course, but they also wanted what Stephen Kellert, Tweedy Ordway Professor of Social Ecology, calls “restorative environmental design,” bridging the gap between nature and people even in the middle of the city. That was going to mean demolishing at least one corner of the Science Hill landscape of driveways, dumpsters, parking lots and a power plant and bringing the place back to life as a campus for people. They also wanted the new building to be energy-efficient, and they set out to achieve a platinum rating in the green-building certification program, Leadership in Energy and Environmental Design (LEED). But they aimed to do much better than that. The typical LEED gold or platinum building performs only about 28 percent better than conventional buildings on energy efficiency, according to a 2007 survey. Kroon Hall planners set out to achieve something more like the architectural Holy Grail, a modern building that wasn’t merely efficient, but carbon-neutral. Dean Gus Speth, who together with Kellert was the driving force behind the project, promised a building that would be “a symbol of the school’s ideals and values and a powerful expression in beautiful form of our relationship to the environment.”

It was an agenda that invited close scrutiny and also elicited some anticipatory schadenfreude. In effect, F&ES was pushing the building community, and Yale itself,  well beyond their comfort zone, with the help of European thinking from the British firm Hopkins Architects and a shopping list of technologies and construction techniques most American contractors had never heard of, much less attempted. The initial response from some university staff included “barely suppressed ridicule” and “almost outright laughter,” Kellert recalled recently. Discussing the carbon footprint of a building could still seem, as late as 2005, like debating the finer points of theological dogma; it didn’t have much to do with the real world. “They thought we were just out of our minds and had no idea what we were talking about,” said Kellert. Even green-building advocates took a wait-and-see attitude. “Yale is one of the great institutions in the world, and if they make a real commitment to green,” said Richard Cook, of Cook + Fox Architects in New York, “we will all be watching to see what they accomplish.”

Four years ago, standing at 195 Prospect Street, you would’ve seen a one-story-high wall filling most of the space between Sage Hall and Osborn Memorial Laboratories (OML). The wall had barred jailhouse windows. Behind the windows was a gas-fired power plant—whining, humming and emitting carbon exhausts—a bleak symbol of business-as-usual in the fossil fuel economy. Finding your way into Science Hill meant sneaking up a driveway on Prospect Street and through a parking lot on one side of the power plant or walking down to the grand, turreted corner entrance of OML and through an archway—into another service yard.

Yale had come to recognize Science Hill’s shabby character as a neglected outpost of the university, and it had developed a plan to transform it into a place students might actually want to stay for a while, rather than just making quick forays from the main campus. But the parcel between Sage and OML would be a harsh test of just how far the university would go to achieve that goal. The site was an industrial wasteland containing contaminated soil, an underground spiderweb of utility lines and the power plant. It also sloped steeply from front to back and from one side to the other. When the architects first saw it, said Speth, “they gagged.”

Fast forward four years, and the same piece of Prospect Street now feels as if the main Yale campus has opened a scenic beachhead into Science Hill. The resemblance has to do partly with the architects’ choice of the same Ohio sandstone used in many buildings on the main campus. As a result, Kroon Hall’s pale yellow coloring makes a luminous contrast with the gloomy brownstone and maroon brick of other Science Hill buildings. But the resemblance to mainland Yale has even more to do with the way the building connects to its landscape.

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Robert Benson Photography

Where the power plant used to stand, an elevated piazza now serves as the entrance to Kroon—and also screens it from the noise and traffic of Prospect Street. On the higher ground to the left, at the north side of the building, there is a courtyard and seating area planted with native ferns and bulbs. On the south side, one story down, a sidewalk welcomes people off Prospect Street into a broad, grassy courtyard, with a rain garden at the far end and access to Sachem’s Wood, the green heart of Science Hill, just beyond. For Kellert, who teaches about the restorative power of parks and gardens, having “the Yale courtyard tradition on both sides” is almost as important as the building itself: “People will be teaching out there, dining out there, bonding out there.” For Speth, the transformation of the landscape raised the promise of actually improving on über Yale: “The Cross Campus and the Old Campus are very nice,” he allowed. “But Science Hill is going to be special.”

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Robert Benson Photography

Though it hardly seems like architecture at all, the south courtyard was the elegant stroke of design that made the entire Kroon building project work, on at least three counts. It isn’t a conventional courtyard but a raised platform, with a green roof of engineered soil just one foot deep.  Beneath it lies a service node where all trash, recycling and delivery traffic for the southwest corner of Science Hill now get handled underground, out of sight. University staff initially resisted the full scope of the service node idea, said Speth. They wanted to keep an above-ground driveway running from Prospect Street along the north side of Kroon to supply Kline Biology Tower. “We really blew a gasket about that. It would’ve been a mess, just as it was before.” Instead, a single driveway off Sachem Street now brings all vehicle traffic into the service node, with deliveries continuing through an underground tunnel to Kline. “I think they knew we were right, but they didn’t want to pay the price.”

The courtyard was also essential on aesthetic grounds. At the beginning of the project, the dark, Gothic mass of OML loomed four stories high at the lower end of the site. Raising the ground level one story reduced the two wings of OML to a more manageable scale, according to Mark Simon, whose Connecticut firm, Centerbrook Architects and Planners, worked with the British design team as on-site architects. It also brightened both buildings by bouncing light off a higher surface. Olin Studio, the landscape design firm, came up with the idea of tapering the courtyard down at the lower edges, so people on the bottom floor of OML now look out on a slope planted with oaks and sweet gum trees. The tapering also lent itself to a stairway in one corner, leading from OML’s grand archway into the courtyard. So for the first time in almost a century, this entrance to Science Hill now opens onto someplace people actually want to go.

That kind of coordinated thinking also figured in the courtyard’s third role as a stormwater-harvesting area. LEED requires new buildings to reduce stormwater runoff by 25 percent below pre-construction levels. So both north and south courtyards, as well as the roof of the building itself, now drain into underground holding tanks. The floating rafts of iris, wild rice and cattails in the south courtyard’s rain garden are meant to look nice, of course. But they also help purify rainwater by removing 80 percent of suspended solids—another LEED requirement. After further treatment, water from the north courtyard gets used to flush toilets and water from the south courtyard for irrigation, avoiding the need for about 500,000 gallons of city water a year.

“It’s the combined power of multiple systems that makes this building much more sustainable,” said Cricket Brien, a design associate with Olin. “If you took one piece of it out, a lot of the other pieces would suffer. Yale was really committed to this idea of integrated planning and design so that systems, buildings and sites work together.”

Integrated thinking, with architects, engineers, landscape designers, contractors, facilities staff and faculty all listening to one another from the start, was also critical to the design of the building itself, and nothing about it felt like business as usual. Yale had recently brought in a hard-nosed corporate construction manager named Jerry Warren, and on a European tour to choose an architect, he and Kellert soon banged heads. “He would bully me and I would just go back at him,” Kellert recalled. “We argued about energy efficiency and sustainability and whether these newfangled approaches worked or not. He said, ‘I’m an engineer. I’ve worked with buildings for 30 years. Don’t tell me how to do my job.’” But Kellert added, “He turned around. This thing wouldn’t have happened without Jerry Warren.”

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Top of Page | Spring 2009 | environment:YALE

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Kroon Hall Rises
Robert Benson

The Ordway Learning Center is located on the ground floor, opposite the library, and has ample space for quiet study.

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Kroon Hall Rises
Gregory Nemec

Rainwater captured on the building’s roof and grounds will be cleansed by aquatic plants and used for toilets and irrigation.

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Kroon Hall Rises
Gregory Nemec

Warmed and cooled air both move almost imperceptibly through an air plenum and multiple diffusers in elevated floors so that it envelops people in a room. The air then exits through vents located above office doors. Low-velocity fans in the basement keep the air moving throughout the building.

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Kroon Hall Rises
Gregory Nemec

Four solar panels embedded in the southern facade provide the building with hot water. On days when there isn’t enough sun, fluid in the evacuated tubes runs through externally powered coils that warm incoming city water.

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Kroon Hall Rises
Gregory Nemec

The photovoltaic panels on the roof’s south side turn sunlight into DC electricity (red), which is converted in a transformer box to AC (blue). The AC is used in conjunction with AC power from the Yale grid and then goes to outlets and lighting throughout the building.

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Kroon Hall Rises
Gregory Nemec

In winter, ground-source heat pumps draw 55-degree to 60-degree water from four 1,500-foot-deep wells in Sachem’s Wood. The heat is removed from the groundwater by the heat pumps and is transferred to a separate water loop through the radiators. Then the groundwater is pumped back into the wells and absorbs heat from the Earth, ready to begin the cycle again. In summer, the process is reversed. The heat pumps take the cool from groundwater to cool the air, and then the water is pumped back into the wells.