LEWISBURG, Pa. - Like sprinters out to shatter Olympic records, Bucknell University student Ali Blumenstock and her housemates race through their showers.

Blumenstock may not be the Usain Bolt of the bathroom yet - she clocks a decent 5:30:00 - but the 20-year-old junior from Havertown expects to best her time in the months ahead.

"It's really important to make the commitment to change, even if it's small things," said Blumenstock, one of the drivers behind the Sustainable Cooperative at Taylor House, a green residence project formed by the environmental club at the college in Lewisburg, Pa. "It's more than energy efficiency. It's a whole lifestyle."

And every gallon counts.

Across the region and the country, the green movement has taken up residence on college campuses. New or renovated dorms have organic suites (Drexel), green roofs (Princeton), geothermal cooling and heating (West Chester) and eco-friendly furniture (Villanova). Known as green dorms, they are building in popularity as economics make more sense and eco-wise collegians expect and demand it.

"More and more students are saying, 'We want to know how green the campus is before we come there,' " said Paul Rowland, executive director of the Association for the Advancement of Sustainability in Higher Education based in Lexington, Ky. (The Princeton Review even has a green campus ranking.)

The U.S. Green Building Council, which gives its seal of approval - known as LEED - to new buildings that meet its standards, has certified about 76 dorm projects since it first offered the rating in 2000. An additional 307 are registered to pursue certification.

Since 2006, the number of green dorms that have registered for LEED certification has doubled each year. In 2008, a record 127 projects applied. Through August of this year, 87 more projects had been submitted. The data doesn't reflect renovations (popular with colleges and arguably more environmentally conscious) or projects such as the Taylor House co-op.

Amy Seif Hattan directs the Advancing Green Building in Higher Education program at Second Nature, a Boston-based organization. In most cases, a dorm is "just a shell in which to throw your stuff and sleep," she said. "A green building is an ecosystem. It's a pleasant place, it promotes health, it encourages dialogue."

While environmentally conscious housing can trim the campus energy bill, it also offers less prosaic advantages, colleges say. Green dorms expose students to the science of sustainability in practical ways and instill a way of life.

"You're getting a generation of kids who will be green natives," said Marie Coleman, a communications associate for the Green Building Council. "It's what they know."

The Bucknell cooperative grew out of the environmental club, a group of 200 students with about 20 to 30 active members known for challenging wasted resources on campus. In 1 week ~ 139,000 sheets of paper are printed in the computer labs reads one sign the group posted on campus, and that now is in the Taylor House common room.

Some of the club students already lived together in the two-story clapboard on the sprawling Susquehanna Valley campus and practiced green habits. But this school year, students decided to raise the stakes, requiring members to apply to participate in the sustainable living co-op, where they would systematically track their impact and brainstorm ways to reduce it. They wanted to change their way of living.

"This is a small version of what we'd like to see happen all over campus," said Blumenstock, one of 13 housemates.

"We try to be more sustainable than the average Bucknell student," added compatriot Katie Koch, 20, of Fairfield, Conn., an art history and environmental studies major.

Last school year, she designed T-shirts. The Look How Trashy I Am one came with a Sharpie. About 75 students on a campus of 3,500 chronicled on the front of their own shirt everything they threw away - and recycled - over three days, she said. Next week, the co-op residents will invite the public for a house tour as part of a four-day climate action festival.

The heart of the sustainable living project, however, is about day-to-day life.

Besides timed showers with a 10-minute maximum, the budding environmentalists compost food scraps, hang laundry to dry, and use lights with a certain stinginess.

A green meter installed in the common room displays real-time consumption of electricity. Blumenstock, who is majoring in environmental studies and Spanish, turns on a light in the hallway to illustrate, and the meter reading jumps from 2.8 kilowatts to 3.8 kilowatts. Another device shows water usage. One of the students, a math major, keeps a daily tally to figure a monthly average - a number to be whittled down.

The project "makes me more aware," said Barbara Summers, 20, an environmental studies and urban sustainability junior and one of the house leaders, who noted that she never really thought about shower times until she moved to the house.