Build green, build more.

That's the gist of a proposal Pittsburgh Councilman William Peduto plans to introduce tomorrow that would give incentives to developers to incorporate features like natural light and flushless toilets into new buildings.

"All throughout the world where development is occurring, communities are making sure it's done right," he said. His proposal has "no financial tax dollars that are being used as an incentive. It's the ability to build it bigger and put more in it."

If council approves and Mayor Bob O'Connor signs on, developers that pledge to build environmentally friendly structures in industrial or commercial areas would be allowed to build 20 percent higher and include 20 percent more floor space.

A 55-foot limit common to city districts, for instance, would be 66 feet for green buildings, adding an extra floor.

To go higher and bigger in neighborhood business districts, developers would need to go through a public hearing and get City Planning Commission approval. There would be no incentive for going green in residential areas.

Developers seeking the incentive would have to use the nationally recognized Leadership in Energy and Environmental Design, or LEED, standards, which rate buildings according to land use, water savings, energy efficiency, natural materials and indoor environmental quality.

The city would get a lien on the property to ensure the developer went through with its promise.

Environmentally friendly construction costs a little more, especially if a building is to be certified as green through the LEED process, said Rebecca Flora, executive director of the Green Building Alliance. She said allowing green buildings to be bigger "is a great way of levelling the playing field" by boosting the amount of rentable space available.

Mr. Peduto's approach is similar to that used in the cities of Acton, Mass., and Arlington, Va., according to the U.S. Green Building Council. A more common approach has been to provide tax incentives.

"If you give someone money to do it, that might work better," said Ernie Sota, a builder and developer who has worked on three green buildings in the area. Still, Mr. Peduto's concept "will have some impact," he said.

Subsidies wouldn't fly here, Mr. Peduto said. "We're going to have a hard time paying the bills next year," he said.

Pittsburgh ranks among the top five cities nationwide for green construction, said Ms. Flora. Environmentally friendly buildings include the David L. Lawrence Convention Center and PNC Firstside Center, Downtown; KSBA Architects headquarters and Blackbird Lofts in Lawrenceville; WYEP Studios in South Side; Greater Pittsburgh Community FoodBank in Duquesne; Carnegie Mellon University New House Residence Hall in Oakland; and U.S. Steel Research and Technology Center in Munhall.

Still, Pittsburgh isn't among the scores of cities with legislated incentives for environmentally friendly construction.

"It's almost embarrassing that we haven't had more leadership from local government," said Ms. Flora. Instead foundations, especially the Heinz Endowments, have led the charge.

Legislation "is a way, I think, to provide increased awareness, leadership and acknowledgement on the part of government that this is a good thing."

Councilman Doug Shields is co-sponsoring the measure, which likely will come up for discussion and a tentative vote July 5.