The Spokane Convention Center will be going green. Its developers are working to qualify the expanded 100,000-square-foot exhibit hall as an official "green building."

"Ultimately, this is driven by (the fact that) we want to create a healthy environment," said Kevin Twohig, executive director of the Spokane Public Facilities District, which is overseeing the expansion.

"We want to improve the ground we're going onto. We want to create a building that is built out of materials that are as sustainable as possible."

The nonprofit U.S. Green Building Council makes the call on LEED - Leadership in Energy and Environmental Design - certification, confirming that a building has a high degree of environmental sustainability.

Since the LEED program began in 2000, more than 180 million square feet of commercial building projects nationwide - about 4 percent of the total - have been registered or certified as green. Membership in the Green Building Council has increased to 4,800 companies from 300 four years ago.

Nationally, 126 buildings have been certified by LEED, including a Bonneville Power Administration building in Vancouver, Wash.; a hospital in Boulder, Colo.; and a high school in Clackamas, Ore.

So far only one convention center, a 1.5-million-square-foot project in Pittsburgh, has achieved LEED certification. But the Spokane undertaking is among two dozen across the country that have registered.

Industry experts say green building is catching on among those who choose sites for conventions, which can bring big bucks into a community.

"It's a competitive advantage. If you're looking at three centers and everything else is equal and your group is concerned about the environment, that puts you over the top," said Mary Power, president of the Convention Industry Council.