Sustainable business is still a term many Philadelphians likely would struggle to define accurately. But it is a far more familiar concept than it was eight years go.

Iola Harper credits Leanne Krueger-Braneky for that.

Krueger-Braneky has been the Sustainable Business Network of Greater Philadelphia's only executive director, advocating since 2004 for small businesses that value social and environmental impact as well as profit.

"She is the mouthpiece . . . for this movement," said Harper, a marketing consultant and cochair of SBN's board of directors.

The question now is whether SBN can find a new leader to sustain that voice.

Krueger-Braneky has announced her intention to leave at January's end the nonprofit she was hired to run when she was 27 years old and it was just two.

Though she will continue to live in Philadelphia, she will be working for a national organization of which SBN is a founding member - the Business Alliance for Local Living Economies, or BALLE - as director of fellowship and alumni. Her work will involve convening those who are organizing businesses toward collective economic impact in communities.

"I'm really hungry to have an impact on the national level," Krueger-Braneky said last week.

Her track record at SBN has been heavy on impact.

When she accepted the job as executive director, her office was a small room off the bedroom of SBN founder Judy Wicks, who was living above what was then her restaurant in West Philadelphia, the White Dog Café. SBN had fewer than 100 fee-paying members, and an annual budget under $100,000.

Membership is 450 today, the budget $500,000, and the agency now rents space in a Center City office building.

Among its work: a 2011 report critical of the city's environment for small business.

City sustainability director Katherine Gajewski praised SBN for helping "to keep focus on opportunities to further support and grow the local economy through our commitments to - and investments in - sustainability."

City water commissioner Howard Neukrug lauded SBN's role in a newly formed green-infrastructure stormwater-industry partnership as "a great support for our Green City, Clean Waters plan." Through it, Krueger-Braneky will continue to work to better position small business for those stormwater-improvement jobs.

Like Krueger-Braneky, her successor "has to have the passion for what we do," Harper said. "It has to be in their blood."

SBN has posted her job at Application deadline is Dec. 28.