As companies become more environmentally aware, that attitude is reflected in the buildings they work in and the ones they renovate or tear down.

Officials at PNC Financial Services, for example, plan to recycle more than 70 percent of the downtown Pittsburgh building they recently began deconstructing, a trend being seen at more demolition sites nationwide.

"Traditionally, if someone were to demolish a building, they would simply go in with a wrecking ball," said Gary Saulson, PNC's director of corporate real estate. Now the company is being much more deliberate in how they take down the building, a process that will run about two months.

PNC Financial bought the city's former Public Safety Building in 2004 for $4.2 million, and immediately announced plans to turn the space into a park. The company previously had built the world's largest certified green corporate building at a site near the building.

Officials estimate the building will yield 11,000 tons of waste — 8,000 of which is recyclable. In addition to the steel and concrete, 24 tons of exterior steel will be used in other products and the foam board ceiling tiles will be returned to the manufacturer to be used again.

"Rather than knocking it down and carting it off to a landfill, if you deconstruct a building and reuse its parts elsewhere, you're saving labor, materials," said Alan Traugott, a founding member of the U.S. Green Building Council. "You are trying to avoid going for new virgin materials and all the embodied energy and associated environmental impact that reflects."

The practice has become more commonplace, Traugott said, as a distribution network for used building materials has sprung up. Pittsburgh-based Construction Junction, a nonprofit retail store for used and surplus building materials, saves thousands of doors, windows and cabinets for reuse every year, according to its Web site.

The demolition of buildings in the United States produces about 124 million tons of debris every year, according to the Deconstruction Institute, a Florida-based group which encourages recycling of buildings and the use of recycled building materials.

"Clearly as our land use becomes much more critical, doing this makes a lot of sense," said Rebecca Flora, executive director of the Green Building Alliance.

Peter Templeton, deputy director of the Leadership in Energy and Environmental Design project and International Programs for the Green Building Alliance, said different municipalities have different requirements. Some of the strongest programs are in place in Washington state and California.

According to the Minneapolis-based Institute for Local Self-Reliance, a nonprofit research and educational organization, some towns across the country have passed ordinances requiring recovery of construction and renovation debris.

In Atherton, Calif., 50 percent of waste from demolition projects must be recycled or diverted from landfills.

Meanwhile, PNC's Saulson said deconstruction actually benefits businesses by creating and sustaining jobs at the plants where old building materials are sent. It also makes fiscal sense for PNC, he said.