When Janet Milkman took over as executive director at the Delaware Valley Green Building Council in 2009, LEED was a largely unfamiliar acronym, and the environmentally and energy-sensitive construction that the accreditation recognizes was not common in the region.

Milkman acknowledges that there were days when she wondered whether she had made the right decision in taking the building council job, intended to promote green construction.

"It was probably the depth of the recession. There was no building going on - green or otherwise," she said Tuesday, able to laugh about those conditions now.

Five years later, Milkman is calling it quits, but not out of frustration. Though her time at the nonprofit organization, formed in 2001 as a chapter of the U.S. Green Building Council, started on a challenging note, it ends with Milkman claiming more accomplishments than disappointments.

At 53, with both children in college, she is returning to her native Massachusetts to live and kayak on Cape Cod. Her next career move has not been determined.

When she was hired, the council's chair at the time, Dan Garafalo, said he hoped that Milkman, who had more than 20 years of experience managing nonprofits in the energy and environmental fields, would "raise the profile of the green-building issues and bring them into the mainstream in industry and policy."

Asked if she believes she accomplished that, Milkman was starting to answer in the affirmative when her successor, Alex Dews, interrupted.

"I would absolutely credit Janet and the organization with making the tent bigger," said Dews, whose appointment was announced late Monday afternoon in a news release by Marla Thalheimer, the council's new board chair. "It's a much bigger network now."

It's a network Dews, 33, of East Mount Airy, has been part of since graduating from Philadelphia University in 2010 with a master's degree in sustainable design. The Phoenixville resident went to work for the City of Philadelphia's Office of Sustainability that year. There, as policy and program manager, he has helped implement and track the progress of the wide-reaching sustainability initiative, Greenworks.

He also has overseen the Energy Benchmarking and Disclosure Program, created when City Council passed legislation requiring all commercial buildings over 50,000 square feet to report their energy use to the city annually, effective 2012. Results became publicly available starting in 2013, enabling prospective tenants to comparison-shop.

Dews begins work at the building council on Jan. 20. Also an adjunct professor at Philadelphia University, he is accredited in LEED (Leadership in Energy and Environmental Design).

Once a community led by designers - mostly architects and engineers - the green building movement now encompasses manufacturers, recyclers, insurance and financial interests, affordable-housing providers, and institutions of higher education, Milkman said.

Philadelphia's hosting of the U.S. Green Building Council's 12th annual conference last year was one of her proudest accomplishments at the council, she said.

In 2009, there were 108 LEED-certified projects in the council's territory, which includes the five-county Philadelphia area and the Lehigh Valley, as well as Delaware. Currently, there are 678.

"What's exciting now is, the industry is back," Milkman said. "People are building again, and they are building better and they are building smarter."