PHILADELPHIA — Negotiations between developers, the plumbers union and the mayor's office here over the issue of waterless urinals have resulted in an agreement that will make the Comcast Center the tallest green building in the country.

Liberty Property Trust, which is building the 58-story, 975-ft. tall Comcast Center, has applied to the U.S. Green Building Council for certification. Part of the Leadership

in Energy and Environmental Design certification proposal was that the building would use waterless urinals, potentially saving 1.6 million gal. per year.

United Association Plumbers Local 690 didn't think much of the idea. Waterless urinals are not in the Philadelphia building code, and the union said it wasn't going to budge in its opposition to granting a variance.

The parties reached agreement in April that water supply piping would be installed behind the wall, although not connected. The installation of the 116 urinals in the building would be considered a five-year trial. The urinals would be replaced during that period if they did not work. And Liberty Property Trust would not install waterless urinals in any other building in the city during the five-year trial. The city's plumbing review board approved the deal.

The issue became a matter of civic pride. Philadelphia was delighted that Comcast made the commitment to stay in its hometown. The Comcast Center is the biggest real estate development in the city center in 13 years.

Moreover, if the Comcast Center lost the title of America's tallest green building, the honor would have gone to the Bank of America Tower in New York. The $540 million structure, designed by the architectural firm of Robert A.M. Stern, is scheduled for completion in fall 2007.