The San Francisco Bay Area sits at the intersection of environmentalism and technological innovation, so it’s natural that this market would produce some of the country’s most innovative green homes.

Of course, the definition of “green” is still under discussion for many within the home building industry and beyond. The general consensus is that green building techniques focus on energy, materials, waste, water, and habitat. For some builders, this means concentrating on design aesthetics, passive use, or holistic design and health. For others, green building takes on deeper, more philosophical tenets of community enhancement and global sensibility.

No matter the philosophy, though, these homes stand apart. Each pays tribute to slightly different green building schools of thought, while personifying progressive green building techniques that set new benchmarks for future builders to follow.

Holland/Yates Residence, Portola Valley, Calif.

What would the greenest custom home in America look like? Would it be energy independent and fossil-fuel-free? What about building beyond LEED Platinum standards to achieve the most credits in its class? Would it invoke regenerative principles to produce even more energy than it consumed?

According to homeowners Paul Holland and Linda Yates, America’s greenest custom home would include all of these principles and then go even farther to educate people on building smarter and living greener lifestyles.

When the Silicon Valley couple began five years ago to design their 5,600 square-foot home in California’s Portola Valley, they wanted more than just a living space: they wanted an experience. Inspired by their travels around the world and by their three children, Holland and Yates envisioned a home with a uniquely green story. 

But this is also Silicon Valley. The culture breeds leadership, innovation, and competition. Holland, a venture capitalist, and Yates, a management consultant, had even loftier goals: Building the greenest custom home in America.

“To be clear, the greenest dwelling would be a yurt or tent,” Yates explains. “But we feel it’s important that we have a gathering space large enough to support the causes and people who are making a difference in the world.”  

Led by builder MGM Construction, the Holland/Yates residence boasts an array of innovative green features, including reclaimed materials and locally salvaged limestone for fireplaces and paving. The recycled steel roof feeds rainwater into a massive 50,000 square-foot cistern for irrigation. The home utilizes a ground source heat-exchange system that relies on the earth’s thermal energy as the sole source of domestic heat. On the drawing board, the home is set to achieve the most LEED for Homes credits of any other project in the country. It is expected to be completed in January 2011.

The house also will be outfitted with the latest clean technology advancements, thanks to Holland’s venture-capital connections. Seven of his clean technology startups are represented in this project. For example, the home’s lighting, climate and irrigation will be automated by Control4 software and remotely operated by Apple’s iPad. SunRun, another venture-funded company, will provide financing for a 40-kilowatt photovoltaic array that will satisfy the home’s energy load, plus the future demands of charging five electric vehicles.

Holland and Yates also hope their efforts serve a greater social purpose by inspiring others to build smarter. Their home is wired to let people monitor its performance online, and the couple intends to share their hard work and research with the public as an open-source project. “We just hope others will carry on what we have started here,” Yates says.

Sausalito-Purhaus, Sausalito, Calif.

The green building movement is in part a response to human health issues related to poor indoor air quality and toxicity issues in buildings. In recent years, comparative risk studies performed by the Environmental Protection Agency (EPA) have consistently ranked indoor air pollution among the top five environmental risks to public health. Yet, as green building certification programs push for energy efficiency and resource management, indoor environmental quality is often overshadowed.

Enter “Bau-Biologie” or Building Biology.

Building Biology is a field of building science that investigates the indoor living environment for a variety of irritants and focuses on how occupants interact with building materials, indoor air quality, and electromagnetic fields. Creating healthy homes and workplaces free from pollutants is the focal point of this green building philosophy, which is concerned about certain practices that can lead to indoor air quality problems. These include the construction of more tightly sealed buildings, reduced ventilation rates, the use of synthetic building materials and furnishings, and the use of chemically formulated personal care products, pesticides, and household cleaners.

For homeowner and designer Renee Rech, creating a low-toxin home is not just a goal, but a necessity. Rech, sensitive to chemicals, has devoted five years of sweat equity to this project, and late this year, perched in the Sausalito hills, the 2,400-square-foot Sausalito-Purhaus will be born.

Part modernist design, part purist oasis, the Sausalito-Purhaus is at the forefront of healthy home building. Created by Rech and her team-Marilee Nelson, a healthy home consultant, and Oakland, Calif., green builder McDonald Construction & Development-the home is designed and constructed using Building Biology principles.

That means that building materials for the house were selected to avoid off-gassing of chemicals into interior environments. In place of gypsum board for drywall, a magnesium-oxide board is used, which is naturally fireproof, mold-proof, and insect-resistant without using fungicides, biocides, or flame retardants.

“Many well- known green building products were researched and tested for use in Sausalito-Purhaus, and even some of them fell short when it comes to health and indoor air quality,” says Rech. “Just because something says it’s green or recycled doesn’t necessarily mean it’s healthy—zero-VOC has become a common term, but there are still dangerous toxins in many of these products.”

Other healthy home features include insulation utilizing recycled blue jeans and interior concrete-work free of fly ash admixtures, which is a toxic byproduct of coal production. The entire home is wired with armor conduit cable to eliminate electric fields. The home features an infrared sauna for detoxification, steam oven and dehydrator for healthy cooking, whole-house water purifier, energy efficient ERV system with whole-house air purification, and non-toxic furnishings.

“We just hope to inspire others to be active consumers and begin a dialogue with manufacturers, architects, and builders and push health into the forefront of the building world,” says Rech.

Learn more about markets featured in this article: San Francisco, CA, Los Angeles, CA.