Metropolitan Washington used 7 percent less energy in 1980 than in 1973 -- at the same time that national energy use was increasing 1.7 percent -- according to a study presented yesterday to the Council of Governments.

The reduction in Washington energy use reflected improved efficiency in the transportation system and in building insulation and operation, said Trevis D. Markle, who wrote the report with another COG staff member Daniel L. Tuttle II. He specifically cited more gas-efficient cars and better-insulated homes.

Markle, who appeared at the COG meeting to summarize the report's findings and to answer questions, said that the average metropolitan Washington household used more energy than a New York household but less than the typical U.S. household. The Washington household, the report said, used 533.1 million BTUs per year, compared with New York's 465.6 million BTUs and the nation's 943.8 million BTUs. A BTU, or British thermal unit, is a measure of heat energy.

One reason the New York energy use figures are smaller, he said, is the city's mass transit system. Washington still relies heavily on the automobile and as a result uses more gasoline and more energy on a per household basis than New York, he said.

Washington area energy costs for 1980 were about $4 billion -- about $3,700 per household and $1,400 per person, the report said. No figures were shown for the 1973 energy cost.

More than one-third of the energy used in the Washington area -- 37 percent -- was for transportation, the report said. The balance was used by the residential sector, 24 percent; steam and electric utilities, 19 percent; the commercial, industrial and federal sector, 15 percent; state and local government, 4 percent; and hospitals, 1 percent.

The most important fuel used here was gasoline, which represented 27 percent of the energy pie for the area in 1980. Other fuels used included natural gas, 20 percent; coal, 17 percent; residual oil, 16 percent; distillate oil, 11 percent; jet fuel, 8 percent; and others, 1 percent.