Harvard currently ranks thirteenth on the Environmental Protection Agency’s list of the top 20 colleges and universities that purchase the most green energy, though final results will not be announced until next month.

The ranking is part of the intercollegiate Green Power Challenge, an annual competition that tracks the amount of renewable energy purchased by 45 schools in 22 collegiate athletic conferences throughout the academic year.

Though Harvard has participated in the competition for several years, the Challenge’s emphasis on the number of green kilowatt hours of power purchased is not fully compatible with the University’s current energy-saving tactics.

While Harvard is also pursuing a diverse portfolio of green energy purchases, the University is striving to curb emissions by increasing efficiency and reducing electricity demand. Earlier this year, University President Drew G. Faust announced plans to cut Harvard’s greenhouse gas emissions by 30 percent of 2006 levels by 2016.

Electricity use currently comprises nearly 50 percent of Harvard’s overall greenhouse gas emissions, according to Mary Smith, the manager of energy supply and utility administration for Harvard.

“Harvard has focused on increasing efficiency and reducing the demand for energy in addition to purchasing green energy,” said Heather A. Henriksen, the director of the Office of Sustainability. “We are looking to reduce emissions through a combination of energy efficiency and reducing of demand through changes in individual personal behavior.”

Harvard University Operations Services, the office that manages Harvard’s utilities, also runs the Blackstone Steam Plant, which decreases energy consumption by providing high-pressure steam to around 200 buildings for space and water heating. This provides Harvard with increased fuel efficiency and reduced greenhouse gas emissions, Smith said.

Harvard’s green purchases are heterogeneous, including wind and small-hydro Renewable Energy Certificates as well as on-site solar generation from panels at the Business School and Science Center, Smith said.

While the EPA rating cites Harvard as having purchased 8 percent of its energy from green sources, Henriksen said the real number falls closer to 12 percent.

Despite the discrepancy, Harvard still lags behind the University of Pennsylvania in the competition—which purchases enough RECs to account for nearly half of its total energy consumption—for the third year in a row.

“While it’s nice to be ranked well on these lists, we would like to make sure that we do everything we can to look at Harvard’s procurement strategy,” Smith said. “This means that we want to consider not only Renewable Energy Credits but renewable energy and on-site sources of energy. We’re very focused on results and will do whatever we can to reduce consumption. If we can all use less we will be even further ahead on these ratings.”