In Yale University's recent announcement  that it had reduced greenhouse gas emissions by 17 percent since 2005, Richard C. Levin, the institution's president, credited several initiatives, among them replacing windows and installing more efficient heating and cooling systems in 90 buildings.
The maintenance projects were only part of the story. A statistic points to a notable behavioral shift: Students in Yale's undergraduate dorms reduced their electricity consumption by 10 percent. They did so through a range of measures, including unplugging appliances and defrosting mini-refrigerators before leaving for vacation. Some of it was also the college's doing, as it installed occupancy sensors that automatically turn off lights in empty common rooms.
That 10 percent reduction occurred in the first year of Yale's new effort. Bob Ferretti, education and outreach manager for the college's Office of Sustainability, credited the early success to students picking off the "low-hanging fruit" (turning off lights, putting laptops on sleep mode, etc.)
In the second year of measuring, though, students' energy consumption stayed about the same. That still puts students on target to meet Yale's goal of reducing by 15 percent energy use in student housing -- measured from the 2005 baseline -- by the end of this year.
But it also raises the question: Are students there willing to do what it takes to knock off the next 5 percent? And, in a broader sense, while students are behind many of the large-scale environmental projects  at colleges across the country, are there aspects of their everyday routines that they're less enthusiastic to change in the name of energy conservation?
Julian Dautremont-Smith, associate director of the Association for the Advancement of Sustainability in Higher Education, said responses to environmentally friendly technology vary greatly. Students tend to be more than willing to adapt to some products -- occupancy sensors and energy-efficient flat-screen computers -- but are more hesitant with others, such as low-flow shower heads.
The more controversial products often improve over time in response to consumer preference, and student resistance dissipates, Dautremont-Smith said he's found. But student behavior typically takes longer to change.
Administrators at Stanford University got a crash course in responding to student complaints this month. Following a spring pilot program that involved installing low-flow shower heads in one dorm, the university replaced more than 1,500 of the old shower heads across the campus with the low-flow variety before students returned from winter break.
Students, mostly in one dorm, revolted. Christian Tom, a Stanford junior who lived in that dorm, said almost everyone on his hall noticed a major drop in water pressure. They signed a letter that Tom sent to the university's housing office voicing their displeasure.
Jonas Ketterle, a Stanford senior who proposed to Stanford's housing office that the new type of shower head be used, went dorm to dorm explaining to students that the change was made to decrease water consumption.
Once facilities management pumped up the water pressure, which had been lower than intended in the dorm, students were mostly placated, according to Rodger Whitney, Stanford's chief housing officer. Tom agreed, but said he wishes that the university had looked for energy savings in other places, such as low-flow urinals.
Ketterle said most of the complaints had to do with process -- the university not notifying students in advance -- and not with the idea of changing the shower heads to conserve energy. He said Stanford administrators fell short in their plan to post notes in the dorms announcing the shower head change. Whitney said the university would think twice about making these types of moves mid-year in the future.
Micah Ziegler, a member and past leader of the Yale Student Environmental Coalition, said students are typically used to taking long showers with intense water pressure. Colleges can get into trouble when they assume students will automatically adapt to appliance changes and understand the thinking behind the moves.
"It's a university's responsibility to educate students about how sustainability is being managed," Ziegler said. "I don't expect flow charts on the wall, but I do want e-mails saying, 'You're saving energy and here's how you're doing it.' Students need to know why they're using a low-flow shower head. When they go off in the real world, they have to make that decision for themselves."
That doesn't mean institutions need to put every dorm renovation change up for a student referendum, Ziegler said. Colleges can set the agenda in certain cases.
"I don't hear anyone complaining that a fluorescent light looks so different than an incandescent one" that is less efficient, he said. "Most people can't tell the difference."
Whitney said Stanford students have typically been receptive to reminders by administrators and students to reduce their energy consumption by turning off power chords and unplugging electronics. The problem, Ketterle said, is that students don't know how effective they are at reducing their energy footprint.
That's why Stanford is drawing up plans for a green dorm that would include a first-floor laboratory where researchers would monitor room by room energy use and student behaviors. Ketterle, the student representative for the project, said the idea is for the hallways to compete in energy-reduction competitions, similar to the university's water usage contest.
Ketterle said he's impressed with students' willingness to turn off lights and unplug appliances, but he's still bothered by the amount of garbage generated in dorms.
Ferretti, the Yale outreach manager, said students might get over the 10 percent energy reduction hump if they kept their room temperatures a few degrees lower.
Students in an environmental task force  there successfully lobbied Yale housing to lower the base temperature two degrees in the winter and raise it two degrees in the summer. But students can typically control, within a few degrees, the temperature in their rooms or suites.
"There are some students willing to go the extra mile and put on an extra layer in the winter," Ferretti said. "If their room is a sweltering 80 degrees, instead of opening a window they can report the problem."
Ziegler said that while some students aren't willing to live in a colder room, they are good about asking the college to repair leaky windows or fix broken exterior doors. Many times, he said, it's students who are urging each other to take shorter showers and decrease the room temperature.
Peer influence is typically the most effective way of changing behavior, said Sarah Hammond Creighton, Tufts University's sustainability coordinator and co-author of the book Degrees That Matter: Climate Change and the University , from MIT Press.
Colleges, she notes in the book, are often hesitant to tell students to lower their load of gadgets plugged into the wall despite the fact that it would save the institutions money. Some colleges ban personal air conditioning units and limit fridge size, but "an energy police state is not likely to be successful," Creighton said.
Tufts officials sweep the dorms at the start of winter break to see if students have turned lights off, closed windows and emptied their fridges. Those actions help save the university $5,000 in aggregate, she estimates.
Vera Chang, a junior at Carleton College who's involved in the sustainability movement on her campus, said students' use of mini-fridges bothers her the most, in part because many halls come with larger fridges. (She admits, though, that she used one her first year.)
Still, it's a tricky task for students to monitor each other. Nathan Wyeth, a senior at Brown University and co-leader of the student group emPOWER, which is pushing for renewable energy purchases, said he's careful not to go overboard.
“I don’t want to be a nag to my friends," he said. "I don’t always say, ‘Did you put your laptop to sleep or did you just leave the room without shutting off the light?' Colleges need to take the lead in some cases."
Creighton said it's also important to keep in mind the role of the non-students on campus. As her book says, "We know that there are few incentives for individual emission reduction actions on campus, particularly because individual departments and research units are not billed directly for energy costs (or savings)."
Few would consider turning off a copy machine or an overhead projector a hardship, but Tom, the Stanford student, said some students are concerned that to make any serious mark in energy reduction, they need to make major quality-of-life sacrifices. And he worries that the water-pressure incident and similar mishaps only exacerbate the problem.
Ketterle said that's a misconception worth addressing.
"I take fairly long showers," he said. "I'm interested in saving energy, but I don't want to -- and I don't think anyone should have to -- sacrifice performance in these cases."