One week after undergraduates overwhelmingly approved a resolution calling on administrators to reduce greenhouse gas emissions, supporters of the proposal are left with the daunting task of figuring out how to implement the mandate from the student body.

The resolution, which passed by a nearly 9-to-1 margin, calls on the Faculty of Arts and Sciences (FAS) to reduce its emissions to a level 11 percent lower than its 1990 output by 2020.

That’s just a one percent larger reduction than Yale has committed to make in the same time period. But it’s a task much easier voted for than done.

For one, the FAS energy output has increased by a third since 1991, according to figures in a report by the Environmental Action Committee (EAC), the group that promoted the resolution.

And FAS is likely to use even more energy as it grows by leaps and bounds over the next several years.

The school currently occupies approximately 8.9 million square feet, and it’s expanding by 11 percent in the next year, according to Faculty Dean Jeremy R. Knowles’ annual letter released this October.

To hold its energy consumption constant over the next year alone, FAS would have to reduce its consumption per square foot from its current level—about 45 kilowatts, according to the EAC report—to under 41 kilowatts.

And then, there’s Allston.

The Allston campus—which will nearly double Harvard’s current size—won’t lie entirely within the domain of FAS. And the University has committed to environmental sustainability across the River.

Still, according to EAC co-chair Jake C. Levine ’06-’07, “most of the buildings over there are going to be science buildings. Those types of buildings, especially labs, use up an amazingly disproportionate amount of energy.”

According to the EAC report, labs make up a quarter of FAS square footage but a half of the school’s energy expenditures.

A further obstacle to a green future will be the FAS projected dip into the red.

The school’s operating deficit is projected to reach $75 million in the fiscal year 2010.

“In the end, it comes down to the bottom line,” Levine said. While facility improvements would increase efficiency, “it’s expensive to renovate any one building because for a certain amount of time, no one will be living in it, and that will cost a lot of money,” Levine said.

On the other hand, lower energy consumption may reduce costs in the long run. The Medical School, for example, is already lowering its energy costs by $100,000 a year by cutting its fume hood exhaust, according to the EAC report.

FAS administrators are taking note. The school is working with the five-year-old Harvard Green Campus Initiative to reduce emissions, according to its associate executive dean for physical resources and planning, Linda Snyder. “We’ve got great programs, and we have a number of things in the works,” she said.

FAS is already at the forefront of the anti-global warming effort—in research, at least. FAS members’ studies have helped to confirm the reality of global warming—perhaps most famously like the work of Roger Revelle, the oceanographer featured in the film by ’69 alum Al Gore, “An Inconvenient Truth.”

Now, says EAC events coordinator Henry M. Cowles ’08, who is also a Crimson arts editor, Harvard needs to put its research into practice, and students should reduce their own energy use.

“You’re in a tricky position when you advocate for reduction on a global level but you’re not willing to sacrifice on a personal level,” he said.

—Staff writer Margot E. Edelman can be reached at medelman@fas.harvard.edu.