A Primer On 'Green'

What makes a building green?

Here are a few requirements: sidewalks to encourage walking; low-flow shower heads, toilets and faucets; energy-efficient appliances; and nontoxic paints and sealants.

Does it cost more?

Yes. The extra cost of construction ranges from 2 to 4 percent, proponents say. Opponents say it can cost 11 percent more.

How many D.C. buildings are green?

Six buildings meet the standards: National Geographic Society headquarters, Environmental Defense Fund, U.S. Green Building Council, Nusta Spa, National Association of Realtors and Herman Miller National Design Center.