The U.S. Court of Appeals for the District of Columbia ruled yesterday that the Department of Energy must reconsider setting efficiency standards for major appliances.

The ruling represented an important legal victory for a coalition of consumer groups and state governments that had sought -- over the Energy Department's objections -- to have the federal government require manufacturers to meet minimum efficiency standards for commonly used major appliances.

The court said that DOE had erroneously interpreted the law regarding energy efficiency standards for major appliances when the agency concluded that such standards were not economically justified and would not save a significant amount of energy.

The appliances addressed in the court decision include furnaces, water heaters, freezers, refrigerators, central and room air conditioners, clothes dryers and kitchen ranges.

Industry officials and consumer groups said they interpreted the court ruling as an order for DOE to issue energy efficiency standards for at least some major appliances, although they acknowledged that consumers might not see such standards for a few years. "The court left little doubt that standards must be issued except in exceptional circumstances," said Alan Miller, an attorney for Natural Resources Defense Council Inc., one of the consumer groups that brought the lawsuit against DOE.

DOE officials said that they "hadn't been able to digest the court's opinion" yet and declined to comment.

Rep. Edward J. Markey (D-Mass.), chairman of the House subcommittee of the Energy and Commerce Committee, which oversees appliance standards, praised the court decision, saying that "the Court of Appeals has made it clear to this administration that it cannot escape its legal obligations by creative but absurd interpretations of plain English."

Consumer advocacy groups said the court ruling could save consumers billions of dollars and eliminate the need for dozens of power plants, but industry officials reacted harshly to the decision.

"The court decision is one more source of frustration on this issue, which persists despite the appliance industry's consistent improvement in operating efficiency dating from the mid-'70s, when the federal government asked for 20 percent improvement in efficiency," said Robert Holding, president of the Association of Home Appliance Manufacturers.

The "net result of establishing federal standards, combined with DOE's reluctance to exercise its preemptive authority, leaves the appliance marketplace in a highly chaotic state," said Jack Langmead, a vice president of the Gas Appliance Manufacturers Association. "Over half of the states currently have appliance efficiency standards, all of which differ in some respects, one from the other. And a layer of federal standards will merely further exacerbate that chaotic state.

"What we need is a single national standard to straighten out this massive confusion," Langmead said.