David Arkin and Anni Tilt, husband-and-wife architects in Berkeley, Calif., live with their two children in a refurbished 1910 farmhouse outfitted with solar panels and a wind turbine. They walk or bike the five blocks to their solar-powered office, a new building beside a creek. It's located three blocks from their son's school and 60 feet from the home plate where he plays baseball. A red electric Beetle is plugged in at the house, charged up for trips into San Francisco. Arkin and Tilt didn't grow up in this progressive university town, which welcomes dedicated environmentalists, but they met here during graduate school at the University of California and then stayed to perfect a certain kind of architecture: clean, lyrical buildings that assimilate resource-efficiency into everyday life. Since co-founding the firm in 1997, the two have produced passive solar houses made out of straw bales, rammed earth mixed with quarry waste, and recycled and salvaged materials, and garnered nearly 20 design awards in the process.

Clients seem to like Arkin and Tilt because they do the job of architects, creating handsome elevations and bright, airy interiors that flow. The houses reach out to the landscape, and the landscape reaches into the houses. But clients soon discover the other unexpected perks of buildings designed to live lean. A great deal of time is spent studying the sun's seasonal angles, capturing or controlling it with clerestories and tilted roof planes. Open floor plans enhance the sensation of light in the round, and salvaged materials add vintage flair to pristine surfaces. With their straightforward gestures and careful response to the site, the firm's buildings mix modern and vernacular forms. But unlike the thin veil between inside and out that characterizes Modernist dwellings, the thick earthen walls of some of Arkin Tilt's homes provide a cozy enclosure that breathes, maintaining comfortable temperatures with minimal need for mechanical heating and cooling. The firm's work isn't just about bringing the outdoors in, it's about the way clients feel when they're inside.

With a mostly residential practice balanced by commissions for eco-resorts, park buildings, and religious facilities, Tilt and Arkin are helping to work out the green building movement's growing pains.“When we founded this thing eight years ago, we decided we were going to wear our environmentalism on our sleeves rather than making it something we did on the sly,” Arkin says. Tilt adds, “We try to make sure our clients feel passionate about both ecology and good design, because we do. It makes for much stronger relationships.”

green light

Arkin, AIA, grew up in rural Wisconsin and spent summers during high school and college as a camp counselor, living in a tent. “I think that cemented my relationship with the natural environment,” he says. “One of the things we're always striving to be within any building is outside.” After finishing a five-year bachelor of architecture program at the University of Minnesota, Arkin worked for Obie Bowman at Sea Ranch, Calif., for two years. In 1991, he enrolled in UC Berkeley's joint master's degree program in architecture and planning. There he befriended professor Sim Van der Ryn, a visionary pioneer in green building and a former California State Architect under Governor Jerry Brown, and worked with him on several planning projects.

Following a brief stint during grad school with the architecture and planning firm Calthorpe Associates, Arkin approached Van der Ryn in search of a job. Van der Ryn put him to work for the next four years doing ecological design and analysis. One project in particular planted him firmly on the path to sustainable design. He was appointed project architect for the Real Goods Solar Living Center, one of the world's largest suppliers of solar technology and now the home of the Solar Living Institute in Hopland, Calif. “In many ways, that rekindled my love of architecture and building,” Arkin says. “At the time, the showroom was the world's largest straw bale building at 5,000 square feet. It completely heats and cools itself, and all the electricity is generated on site. To this day, that's one of our goals for all of our projects.”

Although solar panels and other technological interventions crop up on many of the firm's commissions, its focus is on natural materials and building systems, recycled content, and salvaged resources. The two share a compatible design philosophy, and their talents intertwine. David's strengths run to what the buildings are made of and how they're spanned structurally, while Tilt pays attention to the sense of space and light. Her undergraduate degree in civil engineering and their combined experience teaching structures classes at UC Berkeley underpin the firm's willingness to venture into uncharted territory. “When we're working with straw bale, or any systems that are not conventional, it's about not being afraid but thinking about how it's working on all these different levels,” Tilt says. “When you make some attempt to understand new ways of building, you're more open to the possibility of alternative solutions.”

A native of Northern California, Tilt spent parts of her childhood living in Greece, Ghana, and Brazil, where her father worked as an engineer. Her twin interests in ecology and design took root in the early 1990s. After graduating from Princeton University she spent a year in London designing office interiors and spent another year doing construction management and shop drawings for a large Seattle construction firm. By 1990, she had caught the eye of Fernau & Hartman Architects in San Francisco and worked there for the next eight years. During that time, she also attended UC Berkeley's College of Environmental Design, earning her master of architecture degree in 1992. Her thesis explored the ecology of wood-frame buildings. “A lot of people at grad school were interested in ecology,” Tilt recalls. “My sister works for Weyerhauser, and I got to thinking about what those issues mean.”

Tilt also absorbed the design culture at Fernau & Hartman, founded in 1977 by Richard Fernau and Laura Hartman. “Coming out of the 1970s and '80s, green design was not concerned with aesthetics, only a technical undertaking,” Tilt says. “But they saw it as much more, as something with a lot of life and soul in itself. At some point I began trying to interject more salvaged materials into the projects I was doing. They showed me, as Obie Bowman did for David, that you can do good design and incorporate environmental solutions into buildings. I don't see how you do good architecture without paying attention to these things.”

design jujitsu

Arkin Tilt's design process is far less linear than that of most architects. After gathering the usual information about program, topography, climate, and where the breezes and storms come from, the architects diagram the sun's path for clues as to what time of day and year solar power is available. Local buildings constructed before the days of mechanical heating and cooling also inform the design. “People have been shaping their buildings in response to climate and building with locally available materials for years in inventive ways,” Arkin says. “It's because we've become disconnected from the process of working with place that we have to come to it this way.”

After sketching out three very different design schemes, they and their clients choose one to develop, doubling up on room functions where they can. “The goal we take most seriously is to build as little as possible,” Arkin says. As the design starts to gel, a study model is made out of cardboard and discarded Tazo tea boxes, using their colors and phrases to express the different kinds of materials and textures. “We're recycling while we're designing,” jokes Arkin. Then, depending on the project, it's off to the Pacific Gas and Electric Co.'s Energy Center, where the architects use a heliodon to study the model's interaction with the sun. A spotlight shines on a table that rotates to mimic the sun's path across the house at different times of year. On one project, the heliodon helped the architects size the overhang on a cupola and observe the effects of clerestory windows on the spaces below. Often they'll make a time-lapse video to show the client, taken with a fiber-optic lens placed inside or outside the model.

Tilt insists that, rather than limiting the creative possibilities, green thinking subtracts data that's essentially arbitrary. “I always feel there's an overwhelming number of design possibilities out there,” she says. “Sustainable design is a way of honing those possibilities. You throw out an idea and test it—how it works with the sun in winter—and that eliminates a lot of things. You narrow down pretty fast, which isn't to say there aren't still a million solutions. In that way I find sustainability a really useful approach.”

Salvaged materials add serendipity and wit to every project. In a remodel, old decking may adorn a new wall; a glazed door will reappear on the other side of the house. On custom homes, the architects think salvage when they want to add interest to a simple space. “We're identifying items that have the potential for being met by a salvage material—interior or exterior siding, an old window or door—with the idea that we'll find something between the time of design and the time the builder needs it,” Arkin says. “We've done it enough times that we're comfortable putting it in the plans; we'll build an allowance into the construction contract that covers it, and we'll help the clients find it.”

The back half of their garage is stashed with a stretch of old bowling alley, fabulous metal doors, chalkboard slate, corrugated wire glass, and windows in shapes they like. And at some point in the design, clients may be taken on a treasure hunt for a funky fixture or countertop at one of the East Bay's well-stocked salvage yards. Arkin and Tilt accompany clients on the first trip, showing them what to look for and what to leave behind, like doors out of square. Over the years, they've developed an A-list of salvaged wood suppliers—a handy source for the 32-foot beams they needed for one recent project.

When specing old stuff, Arkin says they're always asking what's appropriate. “While we're inclined to take some risks, we don't do it without thorough understanding and research,” he explains. “There are craftspeople we work with on a regular basis to implement those details.” However, Tilt adds, “At some level it's not for everyone. You can't spec the thickness of a material, the kind of wood, or the color of tile. You have to be loose about it, do a little design jujitsu.”

beyond the bale

Those slightly offbeat flourishes get played out on the larger scale, too. As founding members of the California Straw Bale Building Association, Arkin and Tilt have constructed more than a dozen buildings from straw, which is super-insulating, durable, and abundant. The walls are clad in a vapor-permeable, sprayed-earth technology known as Pisè. Utterly maintenance free, it's a warm natural finish, sometimes with salmon- or ochre-colored striations, and can be troweled smooth or scraped vertically for a rough finish. It's possible that their work in straw bale, a material devoid of standard detailing specs, has pushed Arkin and Tilt to reinvent just about everything they get their hands on. Solar panels often double as shade structures. A solar-panel awning shelters their office entryway and announces the firm's interest in solar energy. The two have also developed seasonally adjustable brackets for horizontal and vertical mounting that they've dubbed Arc 'n' Tilt, tongue firmly in cheek.

With a project architect, a draftsperson, an office manager, and occasional interns, the firm intends to lead sustainable design into an ever more sophisticated future. Arkin and Tilt cultivate a variety of connections that keep them on their toes. Arkin is past president of the national office of Architects/Designers/ Planners for Social Responsibility. Its Northern California chapter established a Green Resource Center in downtown Berkeley and produces an annual trade show called Green Materials Showcase. He also teaches at the Solar Living Institute, and both teach and lecture at UC Berkeley. “More recently I've become aware of the impending crisis we face over energy resources,” Arkin says. “Buildings offer an opportunity to reduce our dependence on oil, because they use 35 percent of the energy resources in this country. We as architects have a responsibility to make that transition possible by designing self-sufficient projects.”

As eco-conscious design catches on, Arkin and Tilt's decision to make their firm a showcase for the environmental cause has turned out to be a smart one. “Our clients have a world view that's much bigger than just themselves,” Tilt says. “That's the delight of what we do—the wonderful people we meet.” Two such former clients are Randy Hester and his wife, Marcia McNally, both professors at UC Berkeley. Arkin and Tilt added an efficient addition to their tiny 1920s bungalow, animating it with clerestory and transom windows and innovative materials such as a terrazzo-like countertop of crushed automotive glass. “They're just brilliant at inventiveness at the smallest scale,” Hester says. “Those countertops make me smile almost every day. Anni and David reduced our energy consumption by 40 percent, and did all those good things. But mostly their design just gladdens our lives.”