Jan. 31, 2004, 1:19AM
LOS ANGELES -- Which is the greenest building of them all?
Is it the National Audubon Society's new urban nature center -- the first edifice in Los Angeles to be powered, heated and cooled solely by the rays of the sun -- its rebar molded from melted handguns?
Or is it the Natural Resources Defense Council's new regional headquarters in nearby Santa Monica -- a building so efficient that it recycles water from its sinks to flush its toilets and uses one-third as much energy as similar structures?
In what the conservation groups call a friendly cross-town competition, not a greener-than-thou spat, Audubon and the council recently squared off to see who would emerge as owner of America's most environmentally advanced edifice.
Each had its partisans. Los Angeles Mayor James Hahn and other political luminaries crowned the Audubon Center at Debs Park on Jan. 13. Last week, actor Leonardo DiCaprio and Hollywood environmental activist Laurie David posed for the paparazzi at the council's Robert Redford Building, which they had helped pay for. Not surprisingly, they called it the champ.
Last week, the U.S. Green Building Council, the nation's leading authority on such matters, declared that the Natural Resources Defense Council office was indeed the greenest building in America, but only by the most minuscule margin of verdant brick and mortar.
One distinct advantage: While the Audubon Center east of downtown is a brand-new structure, the council took an existing building, a former acupuncture school, and recycled it.
Maybe the real winner is Southern California, which now can boast that it is home to the country's top two showpieces of environmental architecture.
"Los Angeles is usually maligned as the capital of sprawl, and with some reason. But there are some extraordinary things happening here," said Elizabeth Moule, chief architect of the council's headquarters."These green buildings are meant to be a practical showcase of what is possible."
The Green Building Council rates structures on a 67-point scale.
Wood must come from forests that are carefully thinned, not irrevocably depleted. Recycled building materials, such as coal ash in concrete blocks, must be widely used. Caulks and paints that release trace amounts of toxins are strictly forbidden.
Only a building in India, the CII-Sohrabji Godrej Green Business Centre in Hyderabad, has scored higher than the Audubon Center and the council headquarters.
Each of the two California buildings has its special charms.
The carpeting in the Audubon Center was made from the Mexican agave plant. Its cabinets and desks were fashioned with boards of compressed wheat and sunflower seeds.
The hardwood floors in parts of the Redford Building were made from bamboo, which grows back with such speed that it can be used as building material without depleting forests. Many of the lightly painted walls appear to be coated in a rough-edged wood, but it is in fact a composite of recycled concrete and sawdust.
The Audubon Center uses solar power to heat water coils wrapped around the entire 5,000-square-foot building during the winter. The system is electronically linked to an astronomical clock in Boulder, Colo., and in spring, it automatically switches gears and uses solar power to cool the building. Bathroom waste is sifted right on site through live cultures in paper-like membranes that eat the contaminants away, and the resulting clean water percolates into the ground. The building is not even connected to the city sewer system.
The Redford Building uses photo sensors to dim lamps when sunlight is bright enough to read by. It also filters and disinfects water reclaimed from rain gutters, sinks and showers, reusing it to flush toilets. The 15,000-square-foot structure contains offices for 36 environmental lawyers and scientists, and contains a public exhibit space and Internet center named for David and DiCaprio on its ground floor.
"In semiarid Southern California, why do we use drinking water to flush toilets?" Robert Watson, director of the council's international energy project and one of the fathers of America's green building movement, said during a recent tour of the Redford Building.
"I have been doing this for 20 years, and I'm still amazed by some of the things in here," he added.