Kate Zernike Higher education can't resist a ranking: best college, best cafeteria, biggest endowment, biggest party school. It says something about what's important on campus, then, that when the Princeton Review releases its annual guide to colleges this week, it will include a new metric: a "green rating,' giving points for things like "environmentally preferable food,' power from renewable sources and energy-efficient buildings. Green is good for the planet, but also for a college's public image. In a Princeton Review survey this year of 10,300 college applicants, 63% said that a college's commitment to the environment could affect their decision to go there. And where there are application decisions to be made, there are rankings. The Association for the Advancement of Sustainability in Higher Education, with more than 660 members, is developing a rating for environmental friendliness; at least six other organizations rated campus greenness last year, according to the group. There are lists from Forbes, Grist and Sierra magazines, and an annual report card from the Sustainable Endowments Institute, a research organization that assesses the greenness of an institution's investment portfolio. And the Princeton Review will give its top marks to