A Northern Virginia builder using well-known construction techniques has successfully built six new houses that are saving their owners as much as 80 percent in home heating costs this winter.

One of the houses, a three-bedroom home on a one-acre lot in the Giles Knoll subdivision in Springfield, cost its owners $73,490 -- including about $2,000 for the special enerty-saving construction and design features.

The houses, all located in the same subdivision and built by Harry Hart, a former Smithsonian Institution employe turned builder, are put together with double insulation and double walls. They face south, which permits the sun to warm them in winter, and have double glazed windows to keep out the cold. They also have an enclosed area inside the front door for the same purpose.

As a result, at least one couple, Thomas and Ronnie Brogan of 7514 Rolling Rd., have had only one oil delivery this winter -- on Jan. 16, when 101.9 gallons were put in their takn.

Based on consumption so far, they probably will use less than 175 gallons for the heating season -- about 17 percent of the 1,200 gallons used by the average house in the Washington ares.

The seasonal bill for the average house will run about $685 this year. The Brogans probably will pay a little less than $100.

"It's great if it works," said Robert Cf. Johnson, executive vice president of the Northern Virginia Builders Association, a group Hart hasnht yet joined. NVBA had planned a couple of years ago to build an experimental energy-efficient house. "but the project bombed," Johnson said.

The association decided instead to wait on the results of two other experimental houses -- one built by the State of Arkansas and the other by the National Association of Home Builders Research Foundation. Johnson said his association is still waiting to find out the results of those experiments.

Hart said that only one builder has expressed interest in his houses, and in the case all the man was interested in was his contemporary design which incorporates some of the features.

"That's fantastic," said James M. Windsor, executive vice president of the Oil Heat Association of Greater Washington. "He's (Hart) really beat a thermos bottle."

The construction techniques Hart used in his Giles Knoll subdivision have been known for years, but apparently no one ever put them together in an energy-saving package because fuel costs lacked the urgency they now have.

The houses' double walls prevent clod from being conducted through lomber into the house -- a problem even when ordinary walls are well-insulated. They have double the recommended insulation in the walls (6 inches) and double the recommended amount in the ceiling (12 inches).

There are no windows on the east and west sides of the house.

With oil costing about 58 cents a gallon, the Brogans, who paid $73,490 for their house and one-acre tract, would pay for the extras in less than four years.

Ronnie Brogan admits' she and her husband were skeptical about the energy-saving claims when Giles Knoll's houses went on sale.

"Truthfully, we didn't buy the house for energy saving," she said. "We just didn't think it would save that much in this area. We bought it for the design and layout."

But she and her husband became believers after they received their first fuel bill -- for 63 cents on Oct. 10 for 1.1 gallons. That amount was how much they had used since their last delivery, on April 21.

The Brogans also save on air-conditioning costs. Their July electric bill ( $43) and August bill ( $45) were only a few dollars more than their january bill ( $40).

Hart, a cheerful, 45-year-old native of Oiwa, decided after 18 years at the Smithsonian that "I didn't like working for the government anymore. Now was the time to move if I was going to do something else."

His decision was helped along when his wife said to him one day, "Why don't you just quit?"

He did, and after taking a course offered by the Small Business Administration ("What they do is scare the hell out of you"), he formed Hart Development Corp.

It was while he was still at the Smithsonian that Hart became interested in energy and how to save it. "We did an exhibit, 'Our Changing Land.' for the Bicentennial. We put an oil pump in the basement of the natural history museum. It was a symbol of the problem."

Later, while looking at other builders' work to get ideas for what he might do, Hart came to a realization: "It kind of makes me cry to go around and look at some of the things going up. No one is paying attention."

Most of Hart's ideas came from to Small Momes Council at the University of Illinois, which designed what it called the "Illinois Lo-Cal House." The council was the first group to make public comprehensive data on energy-saving techniques in home building. Almost all of Hart's ideas, as he freely acknowledges, can be froun in a 1945 publication of the Small Homes Council, which was originally established to develop plans for a cheap housing for returning World War II veterans.

Few of the techniques have been used by builders since then, Wayne L. Shick, a professor of architecture at the University of Illinois, said. "It's a grind, but there's been no prise pressure, and now there is. People are frantic about their fuel bills."

According to Shick, a Lo-Cal-designed house is far more economical than a house with solar collectors. Shick said that a solar system that would save 100 gallons of fuel oil per heating season could cost from $5,000 to $6,000, and is subject to costly maintenance over its life.

There are no maintenance costs for the Lo-Cal features, and it can save up to 80 percent of fuel costs, according to the performance of the Hart homes and a few others that have been built elsewhere in the country.

Shick said one Massachusetts builder constructed a Lo-Cal house that used only $30 worth of heating during the last heating season.

At what will be Lee-Brooke subdivision, his second venture, a few blocks off Rolling Road, Harry Hart is super-intending construction of 39 more Lo-Cal-inspired houses. They'll be on the market in the spring.

Does Hart think other builders will give him competition?

"I don't know," he said. "Houses in Fairfax seem to sell whether or not they are well-designed or well-sited or well-built."