NEW ORLEANS — In this city on the mend, hundreds of state-of-the-art, energy-efficient homes are being built in lower- income neighborhoods, a trend that's outpacing most of the rest of the United States.

More than 500 green homes are being built with features such as solar panels and rain-catching cisterns in neighborhoods that received the brunt of the damage from the 2005 floods following Hurricane Katrina. Hundreds of other homes are being given green upgrades.

"New Orleans is certainly a leader in that regard," said Suzanne Watson of the Washington-based American Council for an Energy-Efficient Economy. "The scale is remarkable."

Green building has traditionally been left to higher-end homes, whose owners can afford the costlier features, said Forest Bradley-Wright of the New Orleans-based Alliance for Affordable Energy. But as New Orleans began to rebuild, nonprofits stepped in with innovative techniques to build eco-friendly homes in lower-income neighborhoods such as the Lower 9th Ward and Pontchartrain Park, he said.

"The destruction caused by Katrina necessitated almost everyone to rethink how to rebuild their home," Bradley-Wright said.

Other U.S. cities are building energy-efficient affordable housing. The Boston Housing Authority, for example, is getting $63 million in federal money for energy-efficiency improvements, the largest public-housing project of its kind in U.S. history. But it's rare for a city to develop so many sustainable and affordable single-family homes, Watson said.

"What's happening in New Orleans is incredibly impressive," said Dana Bourland of Enterprise Community Partners, a Maryland-based nonprofit that supports affordable housing efforts.

New Orleans projects include:

• Five green homes and an 18-unit apartment complex in the Lower 9th Ward developed by California-based Global Green USA.

• More than 150 energy-efficient homes planned for the Pontchartrain Park area, an effort led by actor Wendell Pierce, a New Orleans native best known for his role in the HBO series "The Wire."

• 150 eco-friendly homes planned for the Lower 9th Ward by Make It Right, an initiative started by actor Brad Pitt. So far, 34 of the homes have been built and range in price from $120,000 to $160,000. Energy bills are 75 percent lower than in comparable homes, said construction director Jon Sader.

Resident Neal Dupar, 48, said his new Make It Right home has slashed his energy and water costs by $300 a month. "It's helped a great deal," he said.