As seen on Philly.com.

Armed with microfiber mops and dusters and low-noise vacuums, a group of workers has emerged from the cover of night to lead a revolution. Cleaning crews are boldly steering janitorial carts into office buildings' lobbies, work cubicles, and restrooms when such potentially disruptive activity has long been considered a no-no: in the daytime.

They are buffing and wiping and collecting trash in the middle of other workers' workdays - even as those employees take phone calls, pore over spreadsheets, or write reports.

A popular practice in Europe, out West, and even in corporate-headquarters-rich Atlanta, the movement is barely a ripple in this region. But commercial-property owners expect a steady stream of converts. They cite reasons such as these: Daytime cleaning reduces operating costs - lights and heat don't have to stay on all night, for example. And, as an added benefit, reports of work-station theft all but disappear.

"It's one of those almost-no-brainer changes that you look back and say, 'Why weren't we doing this forever?' " said Dave Campoli, regional vice president for REIT Management/CommonWealth REIT, owners of One Franklin Plaza in Philadelphia, where tenant GlaxoSmithKline (GSK) has been serviced by a daytime cleaning crew from ABM Industries since the fall.

Campoli is in talks with other tenants in REIT's portfolio of 25 city and suburban properties, trying to "build a base . . . who are willing to say yes." To his knowledge, the only other city property that has adopted day cleaning is SEPTA's 20-story headquarters at 12th and Market Streets.

The transportation agency said the change, made 20 months ago, had contributed, along with other greening measures, to a 12 percent reduction in energy use.

Of all the sustainability initiatives, day cleaning is "the biggest bang for the buck; it didn't cost anything," said Marion Coker, SEPTA's manager of strategic business planning and sustainability.

What it did require was adjusting to "someone coming into your office and emptying a trash bin," she said.

At the GSK offices, that "someone" used to be Pamela Seawright, whom ABM assigned to One Franklin Plaza a year ago. Her job now is maintaining the 16 restrooms on floors 10 through 17, as well as the fitness center.