Bet you haven’t heard this one before: how many Yalies does it take to turn off a light bulb? Or, more pointedly, how many Yalies actually do turn off their lights (or computers or stereos or TVs) when they’re not using them? Consider your own suite for a minute, and you can probably see what I’m getting at: we dorm-dwellers have created a well-lit, energy-consuming machine.

True, the college life is a busy one — when you’re dashing off to classes or meetings, or collapsing into bed after a long night, it’s easy to forget about turning off your computer or flipping that common room light switch. And come the bitter New Haven winter, we all want to crank up our heaters as far as they can go. Plus, for those of us who live on campus, energy is essentially a free good. Without the financial threat of an electricity bill lurking in our P.O. boxes each month, we have little incentive to even think about our energy consumption, let alone to change our day-to-day habits for the sake of conservation. “Why bother?” we complain. “It’s such a hassle.”

But here’s the rub: even though we students may not be footing the bill for our personal energy use, the financial and environmental costs of our cumulative consumption are tremendous. According to the energy conservation plan that the YCC passed last month, Yale spends about $28 million a year to operate the Central Power Plant that provides the electricity for our campus. The variable costs of fuel, water, electricity and chemicals to run the plant contribute roughly $15 million of that total. Moreover, the costs of campus energy use go beyond the millions of dollars Yale pays for it. In satisfying our collective demand for energy, we burn fossil fuels, increasing atmospheric levels of carbon dioxide and thereby contributing to global climate change (along with the slew of ecological and economic problems associated with it). According to a report by the United Nations Environmental Programme, “The United States and Canada have among the highest per capita consumption of energy and other natural resources in the world, and they contribute to a disproportionate share of global emissions of greenhouse gases.” In the aggregate, the impact of individual day-to-day decisions about household energy use is substantial and far-reaching.

The monetary and environmental costs of energy consumption are large, but so is the margin for potential conservation — and small changes in student habits could go a long way in the right direction. According to the recent YCC energy plan, a 10 to 20 percent reduction in campus energy use could generate a savings of $5 to 10 million a year, as well as a considerable reduction in the University’s greenhouse gas emissions. The plan calls for a variety of changes in Yale’s approach to energy, including institutional changes in building design and technology, and conservation efforts by students and staff members. A portion of the savings garnered by these measures could be invested in “green energy,” which is not derived from fossil fuels, further reducing the environmental costs of Yale’s energy use.

Yale is in a position to be a real environmental leader in the energy sector, and we students can play a major role in heading up the charge. Simply by being more conscientious about our energy use, our student body can have a remarkable impact on campus-wide consumption. The winners of an inter-dorm energy-conservation competition at Dartmouth, for example, reduced their building’s energy use by 15 percent.

And the truth of the matter is that day-to-day energy conservation really is easy, even for us busy college students. Reductions in energy use, even ones that may seem trivial, are one of the simplest ways for individuals to take direct responsibility for their environment. Flying out the door to get to class? Hit the lights on your way out — it only takes a second. Winter weather giving you the chills? Think about throwing on a sweater instead of dialing up the heat. It’s not some overwhelming difficulty in these energy-conserving habits that so frequently keeps us from adopting them — it’s just that we don’t tend to think about the costs of our energy use. But if we learn to consider the price, both financial and environmental, that is paid for our over-consumption, maybe we’ll remember to flip the switch on that common room light that no one’s using anyway.

So how many Yalies does it take to turn off a light bulb? Just one: you.