Built a decade before today's green building vogue, Oakland's only straw bale house has emerged as a showplace of ancient methods, modern technologies and Bay Area sensibilities.

Now, the three-bedroom family home at 99 Roble Road, nestled in the hills on the Berkeley-Oakland border, is on the market for the first time, with a $1.125 million asking price.

Straw bale homes like this one are beloved for their thick walls. At a practical level, the thermal mass means year-round comfort and low energy bills. The 2-foot thick walls of the Roble Road house soak up sunlight during the day and radiate heat at night. They provide at least three times the insulation value of a typical Bay Area home.

"When the sun goes down, you don't immediately get cold in a straw bale house," said John Swearingen, founder of Skillful Means in Berkeley. "The house retains heat, and your body has time to adjust."

In fact, the Roble Road house requires very little heat, resulting in energy costs of $30-$40 a month. The house has radiantly heated concrete floors downstairs, radiantly heated wood floors upstairs and a wood stove in the living room.

"The thick, textured walls and natural materials provide a snug, secure environment," said Dan Smith, founder of the green design firm DSA Architects, who designed the home. "When you walk into 99 Roble Road, you leave behind the ambient freeway sounds and are welcomed by the earth, by nature."

Swearingen has built straw bale homes for airplane pilots, Silicon Valley executives, eco-minded folks and others. "It's like comparing a wool suit to a polyester suit," he said. "They might look the same from a distance, but you can tell the difference if you're in it."

The natural quiet of a straw bale home enables residents to relax, unwind and create. A testament to that is the spectacular straw bale home built for the late Bay Area composer Lou Harrison near Joshua Tree National Monument, where he composed his last work, "Scenes from Nek Chand," for custom-made steel guitar.

The straw-bale home's earth-friendly qualities are more than skin deep. The environmental benefits begin with the straw itself. Building the Roble Road house literally transformed an agricultural waste product - stalks left after rice was harvested from Central Valley fields - into the home's walls. California rice farmers used to burn the straw, but the state passed a law in 1991 requiring them to phase out the practice.

Straw bale construction gives the straw a productive second life. A baling machine compacts the straw into 2-by-3-foot bricks, which are then stacked, pinned and stuccoed into walls. If dismantled in the distant future, the walls could be used as mulch, rather than going to the landfill.

A straw bale home also uses less wood than a typical wood-framed house. And, as Swearingen pointed out, rice straw is an annual crop, compared with 50 to 100 years for trees used in building. "Straw bale is one of the few natural products that we can build with in California," he said.

Although straw has been used as a building material for centuries, straw-bale construction in the United States first found favor in Nebraska - tornado country. It turns out the straw bales also naturally absorb the shock of earthquakes. Composer Harrison's home in Joshua Tree neighbors six earthquake faults, yet is built solely of straw bales, wire and stucco.

Still, in homes like 99 Roble Road, wood framing provides structural support for the second floor and meets the state's tight earthquake safety standards.

"We've enhanced the performance of the straw bale walls by effectively turning them into plastered sandwich panels, using stronger mesh, better attachments and additional strap bracing," said Smith. "Tests show they work as well as good plywood walls and are a good choice for earthquake country."

Confronting the elements

Straw bale homes also are fire-resistant, waterproof and as pest-resistant as wood framing. Fire is a real fear in the Oakland hills. Roble Road was engulfed in the 1991 Oakland hills firestorm, and the straw bale home was built literally in the ashes of a traditional home.

"Combustion requires oxygen, and a plastered straw-bale wall just does not contain enough air to keep a fire going," Smith said.

Moisture is a more important risk here in the fog-friendly Bay Area. At Roble Road, Smith used a watertight roof with wide overhanging eaves, elevated foundations, good door and window flashing, and a skin of well-weathering plaster to protect bales from rain and ground water.

Rodents can't nestle into a straw bale house because the bales are well coated with plaster, Smith said. And North American termites have adapted to an almost exclusive diet of wood.

Depending on your personal style, building a straw bale house can be more like a pot-luck than a construction project. Straw bale construction calls for much more unskilled and semi-skilled labor than typical homebuilding, and many builders involve their family and friends in the process. At a practical level, volunteer labor saves money. For community projects, like Santa Sabina Center in San Rafael, the building process can engage people deeply in a structure they will later inhabit or care for.

The family that built the Roble Road house hosted two "bale-raising" parties. Dozens of family, friends and neighbors gathered to stack the bales into tidy walls and provide other enthusiastic support. After all, sustainability is also about people, community and connection.

But how about cost?

"A straw bale home costs about the same as other custom houses," Swearingen said. "You still need the foundation, roof, plumbing and so forth. The final cost depends on how much sweat equity you want to put into the project."

The regulatory process has gotten simpler since the straw bale renaissance began in the 1990s. In 1996, California building codes were amended to allow straw bale construction, and most counties allow straw bale based on those codes or similar standards.

Only one in Oakland

Today there are more than 1,000 straw-bale homes in California, but 99 Roble Road is the only one in Oakland, according to Smith, whose firm has designed more than 50 straw bale buildings in California and elsewhere. While most of those are residences, community projects are catching on too, like the Shorebird Nature Center in Berkeley and the LEED gold-rated Presentation Center in Los Gatos.

On Roble Road, the setting itself deepens the home's green credentials. The owners bought the land after the fire and came to a hillside of charred rubble. They cleaned up the debris, tilled the soil and planted fruit trees, native shrubs, more oaks and redwoods. Today, it is a vibrant hideaway that borders on Oakland's walkable Rockridge neighborhood - with BART, public schools and dozens of restaurants. The house has convenient access to freeways, and the thick straw bale walls provide ideal sound insulation.