Flipping off a light switch at the end of the day seems like a simple enough task, but anyone who has noticed a deserted-but-brightly-lit building at night knows that sometimes, it just doesn't get done.

Last spring, a group of students decided to step in. Led by physics graduate student Jolyon Bloomfield, they launched a systematic effort to fan out and turn off lights in two central campus buildings every evening.

In the year since its formation, Lights Off Cornell has evolved into a movement for energy conservation within Cornell's Climate Action Plan. More than 160 students have been involved, and the group now covers seven buildings. So far, the effort has saved an estimated $2,500 and reduced 13 tons of carbon emissions.

It's also helping students develop skills from marketing to computer science. Last fall, students in Computer Science 5150 (software engineering) created an automated website for volunteer scheduling and a smart phone Web interface to record and input data.

The smart phone capabilities save time, paper and tedium, said Alex Visbal '11, project manager for the engineering team.

Meanwhile, the organization has launched an effort to conserve energy and recruit volunteers across campus. That means tailoring the message to appeal to diverse groups, from sororities to other student organizations and staff members, said Natalie Zandt, a senior studying the science of natural and environmental systems and the group's president.

"At Cornell there's such a diverse array of students we're trying to recruit," Zandt said. "We try to pitch it in different ways."

And while lights are the group's primary focus, the group encourages energy conservation in other areas. Volunteers close windows and note overheated or overcooled rooms, for example; and the group is working with Wilson Lab to make electrical wiring changes that they estimate will save the university up to $3,000 a year.

Lanny Joyce, director of energy management in the Department of Energy and Sustainability, said the initiative fills an important need on campus.

"Lights left on in empty spaces are such a visible waste; and the students have created a low-cost solution to help raise awareness and reduce energy use, cost and associated environmental impacts," Joyce said.

It also has much broader impacts, said Zandt.

"More than anything, Lights Off Cornell is about empowering individuals. Many people feel removed from issues like climate change and sustainability because they feel overwhelmed and don't believe that one person can have an impact," she said. "Lights Off gives individuals an opportunity to make a tangible difference, all while earning community service hours. It's a win-win solution for everyone involved."