Case Study:
Eco-design Laboratory

By Nadav Malin

Responding to the hot, dry climate of California’s East Bay hills, Siegel & Strain Architects selected three structural systems, for the design of an educational camp. Each structural option offered a climate-responsive solution to the differing programmatic requirements while enhancing the camp’s value as an educational resource. The program included a dining hall to seat 200 campers, served by a commercial kitchen; two bathhouses adjacent to a swimming pool; and cabins to house 144 campers and staff. Additional space needs, including longer-term staff housing, were identified but excluded from the project due to budgetary constraints. These needs have since been met with conventional buildings.

Nothing about the Camp Arroyo project was simple, beginning with the client group, which consisted of two separate organizations that planned to share the facility. Much of the focus on sustainability came from staff of the East Bay Regional Park District, which codeveloped the camp and intended to use it during the school year to run weeklong environmental education programs for children from area schools. The other client, the Taylor Family Foundation, was amenable to making it a green project but had other priorities as well. The foundation runs summer programs for children with life-threatening illnesses, so amenities such as the swimming pool, lawns, and air-conditioning were deemed critical.

Principal in Charge Larry Strain describes Camp Arroyo as a “breakthrough project for the firm.” Siegel & Strain Architects was selected to design the project in spite of the fact that everything the firm had done previously was much smaller. “None of the four firms on the short list had proficiency with a project of this size,” notes Strain. “They were clearly going for green experience and were willing to give up a background with projects of this scale to get that expertise.”

The 138-acre location once housed a tuberculosis sanatorium. New buildings were sited exclusively in areas that had already been disturbed by prior construction.

Siegel & Strain focused first on building orientation and form for energy efficiency. The team subsequently selected different structural systems for each of the three types of buildings: stabilized earth for the bathhouses, steel frame with straw-bale infill walls for the dining hall, and efficient wood framing for the cabins. Light-colored corrugated metal roofing with large overhangs on all the buildings helps to unify the project visually.

The bathhouse walls are made of cement-reinforced earth, colored to match the soil, connecting the building with the site. The potentially low-embodied energy of this wall system was compromised: First, the soil proved to have very high clay content, so sand was trucked in to augment the mix and give it an appropriate consistency for construction; second and more important, in this high-risk earthquake zone, the walls required a high percentage of cement and had to be reinforced with steel, so their ecological profile is similar to that of standard concrete walls.

For the dining hall, thermal performance to keep out the summer heat was a high priority, and the client had an interest in straw-bale construction. Siegel & Strain turned to structural engineer Bruce King, author of Buildings of Earth and Straw (Ecological Design Press, 1997) for the necessary expertise. The bale walls were coated on either side with 1 1/2 inches of gunite and a layer of plaster, giving them significant thermal mass in addition to the thermal resistance of the bales.

The team felt the thickness of straw-bale walls would feel out of proportion in the duplex cabins, according to project architect Nancy Malone. Instead, they specified 2-by-6 studs and cellulose insulation, with advanced framing to avoid excessive wood use. All of the framing lumber and sheathing were certified according to the standards of the Forest Stewardship Council (FSC).

The designers also developed a sophisticated on-site wastewater treatment system using constructed wetlands that would have been used to irrigate a garden in an old walnut orchard. In spite of the designers’ success in obtaining the permits for that system, the Park District ultimately opted for a more conventional leach field for wastewater due to maintenance concerns. “The conventional system probably requires just as much maintenance,” says Malone, “but it was maintenance that they understood, as opposed to something new.”

An ambitious permaculture-based landscape plan was also scoped out, but was dropped during design as a cost-control measure. Camp Arroyo still intends to develop its landscape along those lines, according to its program director, Kathy Swartz, and in the meantime maintains an organic vegetable garden.

Quality control was a challenge through much of the project, notes Malone. There was a problem with concrete slabs curling at the edges as they cured, for example. While that could be blamed on the fact that coal fly ash replaced 50 percent of the cement in the concrete, Malone points out that the contractors didn’t take standard precautions to ensure an even cure, in spite of the dry heat.

Siegel & Strain focused first on building orientation and form to achieve energy efficiency.

In some cases even a strong commitment from the contractor didn’t go far enough to guarantee compliance with the ecological program. When it came to building the cabins, the framing contractor embraced the optimum value engineering approach to minimize wood use. He happened to absent when the lumber was delivered, however, and the framing crew dove right in. By the time he returned, two of the cabins were largely framed out using standard framing.

While structurally sound, the earthen bathhouse walls developed a problem shortly after construction. Steel reinforcing was used near the interior face but not at the exterior. As a result, shrinkage of the clay and silt during drying caused the walls to curl a little near the top. “It didn’t occur to me that the wall might shrink enough to curl the wall back,” says King. “If I were doing those walls again, I would add rebar on the outside.”

Even with the challenges, the completed project has been a huge success, winning recognition from the AIA as a “Top Ten Green Project” in 2002. That same year, the YMCA of the East Bay took over management of Camp Arroyo, although the East Bay Regional Park District and the Taylor Family Foundation continue to run their programs at the facility. “The buildings are such a teaching tool for us,” says Swartz. She points to the range of structural systems, in particular, as a valuable tool for teaching campers about sustainable design.

Performance issues continue to plague some of the mechanical systems in the dining hall and cabins. Fortunately, the real success of the design is that those systems are hardly needed, even on the hottest summer days. Dr. Gail Brager’s Sustainable Design for Hot Climates class from the University of California at Berkeley’s College of Environmental Design spent 19 days studying the buildings in 2002. With support from the architects and the Pacific Energy Center, they tracked temperatures indoors and out, on various surfaces and in the middle of the spaces. Their results show that even though the evaporative cooler in the dining hall wasn’t functioning properly, conditions remained comfortable indoors through several very hot afternoons.