On a hilltop in Victoria, British Columbia, Ann and Gord Baird lived in a trailer with his two children for 20 months while they hand-built their dream home -- out of cob.

Their funky, multi-generational home has curved, two-foot thick cob walls -- a mixture of water, clay (the glue), sand and straw (the strength) as well as pumice (for extra insulation.)

"It looks like mud when you're building it," says Ann Baird, noting they used a rototiler to mix the ingredients. She says she and her husband fell in love with cob when they used it to build a wood-working shop on their eight-acre site. She says it's inexpensive and so easy to work with that "a kid can do it."

A variety of cob houses exist in Europe, some hundreds of years old, but they are rare in North America. I've written about straw bale, hemp and modular homes, but this is the first cob one I've chosen as "This Week's Green House."

The Baird's "Eco-Sense" project, completed in Dec. 2008, stands out for another reason. It is the first home and one of only three buildings ever certified as part of the Living Building Challenge, quite possibly the world's strictest green building standard.

This standard, launched in 2006, requires homes to generate their own energy through renewable resources, capture and treat their water and use only nontoxic, "appropriately sourced" materials. There are seven different types of requirements and homes must prove, after a year of operation, that they meet at least three of them.

"These are quite simply the greenest buildings in the world," Jason F. McLennan, CEO of the International Living Building Institute said in a statement last week announcing the first three to be certified.

The Seattle-based non-profit institute, which runs the program, gave full certification to The Omega Center for Sustainable Living, a yoga studio in Rhinebeck, NY, and Washington's University Tyson Living Learning Center in Eureka, Mo.

It gave partial certification to the Baird home, which has a two kilowatt solar array that sends surplus electricity to the grid, for achieving the Site, Water, Health and Beauty requirements.

Ann Baird says their pioneering project has become their livelihood. She and her husband now give speeches about sustainable building and paid group tours of their home. "We've had busloads of bankers show up," she says, noting they want to understand how to finance alternative buildings.

They were newlyweds when they embarked on the project, celebrating their first anniversary in the 27-foot trailer they lived in during construction. Neither had built a house before. She sold her prior home to help finance the project and he quit his job to work full-time on it.

Her parents, who have a two-bedroom separate suite in the home, also helped finance the project, which cost about $270,000 for materials and hired labor. They did all the work themselves, except for the wiring and the plumbing. They also had an engineer review and approve their design.

The home has 2,150 interior square feet that includes two kitchens (one for her parents), five bedrooms and two bathrooms.It has 60 solar evacuated tubes for heating hot water and an efficient wood stove for winter heating. It has a green roof as well as efficient LED (light emitting diode) fixtures.

To maximize passive solar gain, most of its high-performing windows are on the south side, which has extended eaves to provide shade in the summer. The home's north side has no windows.

The home has minimized its energy and water needs by foregoing items such as a clothes dryer and flush toilets. Instead it uses clothes lines and composting toilets, in which wood shavings are tossed in to help convert the organic matter into garden compost.

Its materials are all non-toxic, including earthen floors and countertops. Drinking water comes from a well, and rainwater is collected on the roof to be used in irrigation.

Building wasn't always easy. "We hit the wall many times," Ann Baird says, recalling weather and other hiccups. But she says it was well worth it. Doing the work yourself and using natural materials, she says, "create that sense of connection to your home."