CAN A COMMUNITY CUT its energy use 30 percent by the 1990s? Portland, Ore., is going to try. The city has just adopted perhaps the most ambitious energy-saving plan that any American city has yet approved. It includes many ideas that are becoming familiar, from encouraging solar heating to promoting the city's already-good mass transit and requiring city agencies to consider the life-cycle (capital plus operating) costs of everything they buy.

This encyclopedic effort stands out more because in one crucial field, making buildings more energy-efficient, Portland is going beyond encouraging private initiatives. Starting in five years, owners of homes and apartment buildings will have to meet energy-conservation standards before the structures may be sold. Commercial buildings must undergo energy audits within five years and meet conservation codes when they are remodeled or sold.

In many towns, the idea of such dictation would provoke a popular revolt. Three factors seem to have kept resistance in Portland down. First, the plan emphasizes conservation investments with short-term economic payback -- for homes, about five years. Second, ex-mayor Neil Goldschmidt (now transportation secretary-designate) and other local leaders worked hard to educate citizens and solicit their opinions before the plan was approved. Finally, the program builds on the general interest in conservation that is traditionally strong in Oregon. That makes mandatory codes more acceptable and suggests that voluntary compliance will be high.

Is Portland's program a model for the nation? In some senses, yes. It is a good test of the potential of local initiatives -- and of the difficulties of imposing new standards, such as life-cycle costing, on a whole raft of industries. But enthusiasts should resist the temptation to propose "Portland plans" for every city, much less to try to require them by federal law. Such efforts are likely to have the same discouraging results as the campaigns for another Oregon feature, returnable-bottle bills. Conservation programs work very well in receptive communities, but have to be essentially hand-tailored and home-grown.