The government for decades has failed to meet legal deadlines for tougher energy efficiency standards for appliances and other equipment, costing consumers and industry tens of billions of dollars in electric costs, a congressional study said Thursday.

The Government Accountability Office reported that over several decades the Energy Department has "missed all 34 congressional deadlines for setting efficiency standards," with delays ranging from several months to as long as 15 years.

The standards approved by Congress seek to reduce energy use from a broad range of products from refrigerators and home heating systems to electricity grid transformers and electric motors in factories.

If the deadlines had been met on only four widely used consumer products — refrigerators, freezers, central air conditioners and heat pumps — consumers would have saved $28 billion in accumulated energy costs by 2030 — because more energy efficient products would have been on the market sooner, the GAO estimated.

Standards for these products were issued, but were late in each case.

Rep. John Dingell, D-Mich., who released the GAO findings at a news conference, said "the delays have covered many years" and that he did not mean "to single out" the Bush administration. He said the Energy Department in recent months has sought to reduce the backlog of efficiency standard regulations.

Andy Karsner, the department's assistant secretary in charge of energy efficiency programs, acknowledged the department has had "a simply abysmal" record on meeting efficiency standard deadlines set by Congress.

He said the department has begun a program aimed to eliminate the backlog in energy efficiency rules over the next five years. "We have put out a schedule we intend to meet," said Karsner, who attended the news conference.