Ten years ago, Gary Saulson's life was transformed by a telephone conversation and a leap of faith.

Mr. Saulson, PNC's director of corporate real estate, had already started to watch the banking company's new Downtown operations hub, Firstside Center, rise from the ground when he got a call from Rebecca Flora of the Green Building Alliance.

The alliance's mission is to promote energy-efficient, environmentally friendly buildings, and Ms. Flora wanted Firstside to become such a structure.

Mr. Saulson was skeptical. "My vision of a green building at that point was dirt floors and straw walls and people walking around in Birkenstocks, and I don't know if they were singing Kumbaya but they might have been."

Still, he agreed to set up a meeting with Ms. Flora, and before that session was done, "I had committed to making Firstside a green building, even though it was well under construction.

"I had absolutely no idea what I'd committed to. I knew I had committed to doing the right thing, but that's as far as it went."

Today, PNC says it has more LEED-certified "green buildings" than any other company in the world. LEED, run by the United States Green Building Council, stands for Leadership in Energy and Environmental Design, and comprises a rating system for making sure a building is environmentally sound.

"It's kind of like the UL label on an extension cord, showing that some independent entity is saying a building works like it is supposed to," Mr. Saulson said.

By the end of this year, PNC will have 61 buildings in 11 states that either have the certification or are in the process of getting it, he said, including the firm's new office-housing-hotel complex Downtown.

Most of the green buildings are bank branches, and one day recently, Mr. Saulson led a road trip to one of the newest branch buildings, off Route 8 in Richland.

The most notable feature of the branch at first glance is the bank of windows near the roof line that let natural light spill into the building.

"This building is built around the windows," he said, because "people really excel" when they get to work in natural light. At Wal-Mart, which also has a green building push under way, studies have even shown that products displayed at the end of an aisle under a natural skylight will post higher sales than the same items sold under artificial light, Mr. Saulson said.

The glass in the Richland branch's windows has a thin, tinted film sandwiched inside, making them three times more efficient than typical commercial windows, he said. In the late afternoon, when the sun can slice into the building, the tellers have control over motorized blinds that can cut the glare.

The branch is bordered by low-water plants that need only concentrated watering for the first couple weeks, and after that can subsist on natural rainfall.

When customers walk into the branch, they cross a hog hair carpet that is especially designed to glom onto dirt and keep it from being tracked inside, "so you increase the air quality in the building."

The flooring in the building is a recyclable terrazzo made of ground-up cement and bits of glass; the brick walls are prefabricated to cut down on construction time; and interior panels are also built ahead of time, using recycled steel.

The branch is heated and cooled by a high-efficiency unit on the roof and lit by long-lasting fluorescent bulbs.

Even though each branch is slightly different, they are all based on a prototype that was worked out by Mr. Saulson's team with the guidance of PNC's environmental consultant, Paladino & Co. of Seattle.

The philosophy the team adopted, he said, was "let's forget about any bank branch we've built in the past. If we were designing a branch from scratch, what attributes would it have and more importantly, if our objective is to build the most affordable and most efficient green bank branch, what would we do?"

No item is too small to fall under that spotlight, he said. For instance, when it came time to consider water heaters for the branches, team members first suggested standard home-sized 60- to 80-gallon water heaters.

"But I said, 'Why?' " Mr. Saulson recalled, and after figuring out that the main water needs in a branch would be employee hand washing and occasional cleaning, they decided to install five-gallon water heaters, "and guess what, it works just fine. You really need to go back and challenge everything, and realize that there is nothing that's sacred."

By focusing on cost as much as green materials and practices, Mr. Saulson said, PNC has been able to build the new branches for about $2.6 million, roughly $100,000 less than some competitors are spending on traditional branches.

Once they open, he said, they use 34 percent less energy and 29 percent less water than traditional branches.

Mr. Saulson grew up in Arizona, the son of a man who built wooden bed frames for box springs.

Even though he could never get his father to modernize his dirt-floor, tin-roofed plant, his dad taught him his first lessons in total recycling.

His father bought a million board-feet of lumber a year and planed it himself. The resulting wood shavings were sold to horse owners for bedding, and the scrap wood was made into surveying stakes and concrete spreaders.

After graduating from George Washington University, Mr. Saulson decided to defer his plans for law school -- a delay that became permanent -- and worked in commercial real estate in Phoenix.

He jokes that he came to Pittsburgh 18 years ago "for the weather." In fact, he entered the company as the "OREO manager," an acronym that stands for "other real estate owned" and refers to the buildings PNC acquired because of loan defaults.

Eventually, he became chief of all the company's real estate operations, including construction, remodeling and food service.

Five years ago he put many of the lessons he had learned to work when he built a new home in Upper St. Clair using green construction principles. Most of the tile there is recyclable and heating-air conditioning is high efficiency.

At work, the entire floor where his office is located at Two PNC Plaza on Liberty Avenue, Downtown, has been turned into a giant testing lab for green materials.

Not only does the company test all the fixtures, lights and materials it puts into its green buildings, but manufacturers now regularly approach PNC to try out prototypes.

Right now, for instance, PNC is testing an electric-eye urinal that uses seven low-water flushes in a row before using a full-water flush the eighth time.

"In an office environment, with the number of people who use a urinal," he said, "is there any chance it's going to go two weeks before you get to the eighth flush? No."

It's just one example of how the construction and materials industries are changing, Mr. Saulson said.

"When we built Firstside" a decade ago, he said, "only a couple manufacturers made low-VOC (volatile organic compound) paints. Now every major manufacturer makes low-VOC paints, and you can buy them at Home Depot and Lowe's.

"When we built Firstside, there were only a couple of manufacturers making carpet that was environmentally friendly and there were only a couple of patterns available. Now every major commercial carpet company makes environmentally friendly carpet and there are thousands of patterns available."

Companies like his have helped create that change, he said, but most of it has occurred "because the consumer has spoken; there's tremendous consumer demand, and that's going to continue."

"This is not a fad. This is not Pogs. It's not Beanie Babies. It's here to stay."