CASE STUDY: COTE TOP TEN WINNERS
Garthwaite Center

By Christopher Kieran

The Garthwaite Center for Science and Art at the Cambridge School in Weston, Massachusetts, serves as a classroom, laboratory, and gallery space for the K-12 private school. The Boston-based firm Architerra developed a simple aesthetic for the building that does not immediately convey the innovation of its design, which creates continuity between interior and exterior space and serves as a tool for education. “It grows on you,” says COTE juror Gail Brager of the University of California, Berkley. “It becomes more impressive the more deeply you look at it.”

The two-story, 22,000-square-foot building features site-specific, regionally sensitive solutions exemplary of bioclimatic design. Huge windows emphasize views of the quad. Surrounding trees, visible through a clerestory, give the building a tree-house feel. Cutting 18 feet into a rocky hill allows the building to “grow” out of the ground a feeling enhanced by placing all seven exit doors at the natural grade, so the floor levels mimic the hillside they sit on. Excavated rock was crushed and reused as gravel. Even the land displaced by the building is fully incorporated into the project, as Architerra also reused salvaged boulders to create an informal amphitheater outside.

Oriented on an east-west axis (facing 15 degrees west of south), the building is optimized for passive solar heating. Large overhangs are dimensioned to admit maximum daylight in winter, while blocking all direct sunlight from the double-height glass front during summer months. A partial green roof provides insulation and is visible through the clerestory windows from most everywhere on the second floor. Architerra principal Ellen Watts says, “People first know it’s a special building by the audio track,” referring to the sound of trickling water produced by the main atrium’s wetland planter.

Radiant-floor heating reduces the need for noise and air distribution. Garthwaite’s reliance on natural ventilation is impressive for the New England climate, which varies to extremes. Only the data center and art galleries use mechanical cooling. Over 90 percent of occupied spaces have operable windows, the openings of which are positioned for cross-ventilation. A digital control system that enables remote monitoring supplements an efficient displacement ventilation system. An enthalpy wheel recovers 87 percent of the energy from exhaust air and uses it to precondition ventilation air. A super-insulated building envelope helps stabilize interior temperature.

High ceilings and large exterior windows bring in plenty of daylight, augmented by light-colored surfaces, interior windows, and exterior glass with highly visible light transmission.

The school insisted the design process involve students from the outset. In lieu of an interview, competing architects came to the school to run green workshops for the students. Students produced a preliminary tree survey that was used during design to maximize preservation of existing trees, participated in every design meeting, and took hard-hat tours during construction. Watts admits that such intense student engagement was terrifying at first. When her son heard that students were part of the selection committee, he warned her, “You guys are toast.”

The result was that Architerra produced a building with enormous educational opportunities for the students, who are now analyzing the building’s performance, taking photometric readings to compare daylight levels in the atrium with model predictions.

Exposed building systems offer additional teaching opportunities. A glass-walled mechanical room allows students to view toilet composters and other green systems. Outside, students can see how the boiler burns 100 percent recycled wood pellets (a byproduct of sawmilling), providing 80 percent of the building’s heating needs with a 67 percent reduction in greenhouse-gas emissions compared with a conventional boiler. The wetland planter designed by the botany teacher fosters education about hydrological cycles and species diversity. The exposed structure and systems enable students to observe how buildings work. The building itself is a classroom.

The facility was not permitted to use the local sewer system, so all sewage is treated on-site with composting toilets, an underground graywater bioreactor, and a leaching and recharge field. In addition, all stormwater had to infiltrate on-site. The green roof reduces runoff, and an underground rainwater-discharge system is fed by roof gutters and trenches around the building.

Budget issues, combined with a determination to meet sustainability goals, forced Architerra to minimize cost premiums of green features. The cost of triple-glazed windows was mediated by using affordable fiberglass windows in standard sizes and colors. Floors were finished by simply polishing the structural concrete slabs. Galvanized ducts hang in full view. The Douglas-fir timber frame and its bolted-steel connections remain exposed. Watts adds that, thanks to accurate milling and pre-drilling of the frame by a local fabricator, “the frame went up like a Tinker Toy. It was perfect.”

The simplicity of the design aesthetic is a direct result of the client’s and Architerra’s commitment to creating a relatively low-cost, sustainable building. It’s the exaltation of simplicity not the resignation to it with which the Garthwaite Center says: What you see is what you get. And in this case, how you learn.