SAN FRANCISCO, Calif. — Their projects range from multi-unit developments geared toward the homeless in Seattle to single-family homes built one-by-one to reinvigorate a degraded Atlanta neighborhood.

They are developers who have built green affordable housing in the some of the country's hottest housing markets. They gathered Thursday to discuss successes and lessons learned from incorporating green building principles in their projects.

The roundtable discussion was part of Green Homes and Sustainable Communities, a two-day symposium on green affordable housing sponsored by the Institute for Professional and Executive Development.

"One of our biggest challenges was understanding what green was all about," said Pete Hayley, executive director of University Community Development Corp. in Atlanta, the first CDC in the country to build green single family homes as part of the Green Community Program from Enterprise Community Partners.

The agency is close to meeting its goal of completing 15 green single family homes. Hayley estimated the homes save buyers 15 percent to 20 percent off their total utility packages. He found using green criteria cost about $2,100 more per house. Additional green features cost about $1,100 more.

Using the same team to design and build green affordable housing projects helped Jeff Oberdorfer trim the learning curve of building green.

He works as the executive director of First Community Housing in San Jose, Calif., a non-profit housing corporation that gives its residents Eco passes, which are good for unlimited use of the county's bus and light-rail lines.

The organization's Casa Feliz project in San Jose added a green roof, a much cheaper alternative to building a $300,000 storm water drain. The roof, which boosted the 60-unit building's LEED score enough to earn gold certification, now doubles as a habitat for the Bay Checkerspot, an endangered butterfly.

Oberdorf plans to include green roofs in all future projects when possible.

"If we can't afford it, we shouldn't do it," he said. "Otherwise, I need to know why we shouldn't."

Sharon Lee, executive director of the Low Income Housing Institute in Seattle, wasn't sure how a no smoking policy would work at the Denny Park Apartments. The 50-unit project boasts planters to catch rainwater and exterior insulation that returns 20 percent more heat than required by code.

Residents, about 20 percent are formerly homeless with children, welcomed the no-smoking rule.

"Our residents are very adamant, and are even policing each other," she said.

Dennis Wilde, principle of Gerding/Edlen Development Co. in Portland, Ore., implored attendees to take into account a building’s orientation to save potential headaches and money. He also advised continuing education to help live in ways consistent with the philosphies behind green buildings.

Gerdin/Edlen, which has more than 30 projects designed to LEED certification, strives to create a "20-minute lifestyle" in its communities. This concept means residents can walk to work, shop, eat or have fun within 20 minutes.

"It’s more important to build great places," he said, "rather than great buildings."