SEPTA, the region's expert on transportation, is out to establish itself as a model in how companies can operate their offices more energy-efficiently.

Just be prepared to deal with cleaning crews vacuuming around you while you're at your desk.

SEPTA announced Thursday that its 20-story headquarters at 1234 Market St. has been awarded an Energy Star rating from the U.S. Environmental Protection Agency for energy-conservation efforts.

One of the most cost-effective changes did not cost the cash-strapped SEPTA anything to implement. But employees had to adjust to cleaning interruptions during their workday, such as their wastebaskets being emptied or desktops being dusted.

SEPTA switched its cleaning contractor from nights to days about 18 months ago to, in part, eliminate the need for most lights at its headquarters to remain on after hours.

That change has contributed to a 12 percent reduction in energy use SEPTA says has resulted from all its greening initiatives.

Those have included the installation of motion-detection light switches, more efficient chillers and boilers, and less energy-hoggish elevators and escalators. Film has been applied to south-side windows to eliminate the sauna effect the sun was having on offices there - and the need for power-hungry fans to beat the heat.

Together, the changes have resulted in more than $100,000 in energy cost savings from 2008 to 2009, said Marion Coker, SEPTA's manager of strategic business planning and sustainability. How much of that was from the cleaning-schedule change is not known.

More efficiency is on the way, Coker promised. SEPTA is testing LED lighting in some areas of its headquarters for possible use throughout the entire building, as well as at its train stations and bus depots, Coker said. A decision on whether to use the Market Street roof for wind-power capture is expected early next year.

SEPTA's Energy Star is the 42d awarded in Philadelphia since the program's inception in 1999.

What SEPTA has achieved in energy efficiencies "reflects two important trends," said Janet Milkman, executive director of the Delaware Valley Green Building Council. "First, that government agencies at all levels are taking the lead on energy efficiency . . . second, that human behavior is the next great frontier in operating efficiencies. We've made great strides in energy-efficiency technology, systems and materials, and now we have to work on changing our practices."

Like cleaning offices during the day.

"In the beginning it was a little bit of an adjustment," Coker said. "Now . . . most people don't mind it at all."

Contact staff writer Diane Mastrull at 215-854-2466 or dmastrull@phillynews.com.