When bank executive Gary Saulson told his project team that he wanted to turn a partly constructed operations center in Pittsburgh into a “green” building, they called him “well-intentioned” – but “crazy.”

Five years later, no one is questioning Saulson’s sanity.

Thanks to midcourse changes in the building’s design, materials, lighting, and heating and cooling systems, the 647,000-square-foot steel, stone and curved glass structure overlooking the Monongahela River spends $1.5 million a year on utilities – 26 percent less per square foot than one of the bank’s comparable standard buildings.

Today, Saulson, director of corporate real estate for PNC Financial Services Group Inc., is overseeing the construction of new green PNC branches.

Green construction and renovation techniques are spreading in the commercial real estate industry.

Innovations – such as sun-reflecting ceramic dots in windows, giant vats of ice for overnight energy storage, plant-covered rooftops, bigger eaves and compact fluorescent lighting – are being used in structures ranging from an unassuming PNC branch that opened last month in Ashburn, Va., to the new Bank of America building that will soon be New York City’s second-tallest skyscraper.

The new designs have been spurred not only by concerns for the environment but also by the cold, hard calculation of the potential savings in energy bills.

Commercial buildings devour more than a third of the nation’s electricity. During heat waves, they often rely on auxiliary generators that are less efficient and more polluting than electricity on the grid.

While industrial use of electricity has flattened over the past decade, consumption by commercial buildings has risen about 4 percent a year, according to the Energy Information Administration.

Energy-efficiency experts say that better construction techniques, new energy-saving devices and smarter management can reduce electricity consumption by 20 percent in older commercial buildings and up to 50 percent in new ones, vastly reducing air pollution and utility bills.

“Perhaps the flashiest green building will be the 945-foot Bank of America tower under construction on West 42nd Street in Manhattan.

Architect Robert Fox used a computer model to determine the energy effects of altering the walls, ceilings, mechanical devices and other parts of the 2.2 million-square-foot building.

As these techniques become more common, costs are falling.

Fox said “greening” the tower will add just 2 percent to its $1.3 billion cost.

“One of the more important things is to understand how your building acts,” Fox said. “It’s not just a matter of how much insulation you use.”

“Our goal is to absolutely consume the least amount of power,” Fox said.