A half-dozen families have signed up since the center opened a few weeks ago, and some of the parents are quick to say they're not rabid environmentalists. Alyson Fuchs, who enrolled her 6-month-old daughter, Sadie, says she was attracted by the building's cleanliness.

"I'm not a gung-ho environmentalist," said Fuchs. "But when we were looking at other day cares, we went into an infant room and it smelled like they had washed the room in bleach, and that made me sad."

Back in the center's lobby, the blue slippers come off and there's a gathering in the "imagination" playroom, complete with a bubbling fountain and a stage where children can perform.

Klaus sits at the foot of a miniature treehouse, doing a bit of imagining herself. Her business has plenty of growth to go — there's room for 268 children — and she's already working on plans for summer camps, for a kindergarten class, for a "family concierge" to coordinate doctor's appointments and other events.

"We've crafted the perfect child care center for me," she says with a smile.

She'll soon find out how many others share her green vision.