When it comes to building projects, this one's a monster.

The construction zone is essentially the entire country. The builders are a variety of specialists, including architects, plumbers, masons, and lighting, heating, ventilation, and air-conditioning experts.

Since July, they have been meeting in cities - they were in Philadelphia last month - to construct not with bricks and steel beams, but with words.

The goal: a code to guide all development of green commercial buildings in the United States.

The International Green Construction Code would, as its name implies, also be available to other countries. But drafting it has been the work of U.S. construction professionals who share a desire for the built environment to incorporate more green features.

Pennsylvania is one of only two states with a government representative on the 28-member drafting body. The other is California, the only state to have a green building code.

The Sustainable Building Technology Committee is an arm of the International Code Council, a Washington association of 50,000 members that develops residential and commercial building codes and standards that states, counties, and municipalities adopt or use as a guide in creating their own.

The Green Building Code would address only commercial development. Last year, the International Code Council and the National Association of Home Builders developed green standards for municipalities and other governing bodies to use for residential construction.

Like most building projects, the green construction code is not expected to be without controversy when the first draft goes public in March for evaluation and input.

"We'll have early adopters and early supporters, and we'll have people who are dead set against it," said Maureen Guttman, Pennsylvania's representative on the committee. She is executive director of the Governor's Green Government Council, the state's sustainability office.

Typically, building codes cover health, safety, and welfare issues to ensure a structure's reliability for use. A green building code - which Gov. Rendell has called for in Pennsylvania - does the same "from a more global perspective - the health, safety, and welfare of the planet," Guttman said.

In her view, encouraging so-called higher-performing buildings - those, for instance, that use less water and electricity and more recycled materials - "is a community and ethical obligation."

"That's kind of a leap in thinking," she acknowledged.

It's the kind of thinking that California, which adopted a completely voluntary green building code in July 2008, is looking to make mandatory. The state's Building Standards Commission is scheduled to vote Jan. 12 on several proposed mandatory provisions, its executive director, David Walls, said.

Some of the proposals call for reducing indoor water use by 20 percent over conventional construction and cutting construction waste by 50 percent.

The public-comment period on the first draft of the international code will run through next summer, concluding with a hearing in Chicago in August. A revised draft will be considered at hearings in spring 2011 in Dallas, with the code council slated to adopt a final version that year at its annual convention in Phoenix.

In the 1990s, Guttman said, construction requirements resulting from the Americans With Disabilities Act were initially seen as "an enormous challenge." Now, they are "so ingrained with what we do, nobody talks about it."

She foresees sustainable-building requirements following the same path, "particularly since it is so clearly shown that to build good, sustainable buildings is good business."