When it comes to making California an environmental model for the nation, Steve Jensen, Napa’s chief building official, is doing his part.

Jensen was part of the 11-member California Building Standards Commission that last month adopted the nation’s first “green” building code to cut energy and water usage.

When this code filters down to cities and counties, new construction standards will require that buildings drive down energy use by 15 to 20 percent compared to current averages, while water allowed for new landscaping will be cut in half, Jensen said.

California already has the toughest energy standards in the nation. By next summer, the state code will be 50 percent tougher than any other state, Jensen said.

“I’m very proud of what I’ve done,” said Jensen, who oversees the city’s building department. “I think it’s very progressive for California to take the lead.”

Green enough?

The California Building Standards Commission took a year and a half to adopt the new standards, which were vetted by experts and subjected to public hearings.

Most of the standards won’t become mandatory until the end of 2010 when a new state building code takes effect, Jensen said.

The building industry generally supported the new policies, recognizing that the status quo wasn’t good enough. Environmental groups wanted the state to aim even higher, Jensen said.

The new state rules will set the floor for environmental standards, not the ceiling. In the Bay Area, many communities will set higher energy conservation goals, wanting to do more to roll back the effects of global warming, Jensen said.

Groups such as Sustainable Napa County are expected to advocate greater energy conservation measures, he said. The city of Napa is developing new conservation requirements that may also set a higher bar, he said.

Not every part of California is competing for green honors, Jensen said “You have places in the (Central) Valley where green is not that important. With a floor, everybody has to address these issues,” he said.

The new rules give builders choices in how to improve energy efficiency. Some may choose thicker insulation and passive solar features, while others opt for other techniques for lowering a building’s carbon footprint, he said.

The new standards cover virtually all construction, including homes and commercial buildings, schools and hospitals.

New buildings will meet today’s “LEED Certified” standard of the Leadership in Energy and Environmental Design organization and qualify for “Build-It-Green” honors, state officials said.

Jensen noted that “Build-It-Green” and LEED standards are likely to raise their requirements even higher, inspiring builders to do more than California’s new minimum.

After motor vehicles, the construction and operation of buildings are the second greatest producer of greenhouse gases, Jensen said. The new rules will help the state meet its goal of rolling back total greenhouse gas emissions by 30 percent by 2020, he said.

Environmental groups such as the Sierra Club wanted the state’s new standards to become effective immediately. The state commission decided that local government and the private sector needed time to plan implementation, he said.

Toughening requirements on new construction is a way of picking the “low hanging fruit,” Jensen said. In the future, rather than make new buildings as tight as drums, society might get more bang for its energy conservation buck by encouraging owners of existing homes and businesses to buy more efficient heating and air conditioning and add insulation, he said.

Jensen imagines a system whereby builders pay into a conservation fund to subsidize these retrofits.

Napa is currently in the process of inventorying greenhouse gas emission of city buildings and operations. Once the information is in, plans will be developed to reduce emissions. This is a countywide effort being coordinated by the Napa County Transportation and Planning Agency.