The Swedish housing industry, supported by advanced technology in factories and a stringent building code, is producing homes twice as energy efficient as those of its American counterparts, according to a recent report.

The systematic approach the Swedes take to energy conservation, which involves support from government, industry and homeowners, contrasts sharply with practices in the United States, where energy efficiency is looked upon as "a fad," according to Henry Kelly, one of the report's authors and executive director of the American Council for an Energy Efficient Economy. The report's findings are contained in a new book, "Coming In From the Cold."

"It's not that the best U.S. builders are dumber than the best Swedish builders, it's just that the whole practice in Sweden is at the level of the best builders in the U.S.," said Kelly, who is also a senior associate at the Congressional Office of Technology Assessment.

Kelly claimed that Swedes emphasize durability and quality on all new homes, not just on high-priced houses, as is the practice here. The energy efficiency of Sweden's homes -- where indoor temperatures, despite the country's severe climate, are higher than those in the average American home -- is just one result of that quality.

The role of the Swedish government, mostly through its loan and housing code programs, is the key to the nation's energy efficiency, Kelly and co-authors Lee Schipper and Stephen Meyers concluded.

Sweden, a country proud of its tradition of making home ownership practically "a citizen right," offers most home buyers government-subsidized loans, which include an attractive 5.5 percent interest rate during the first year, the report said. To qualify, however, homes must meet strict building codes, including energy-efficiency standards.

Because 90 percent of Sweden's new-home buyers obtain these government-subsidized loans, there has been "an enormous effect" on energy efficiency, Kelly said.

Loan programs run by the Federal Housing Administration and the Veterans Administration in the United States contain energy provisions, but at levels "considerably below the Swedes'," Kelly said. He added that, because such loans are available to only about 15 percent of American home buyers, energy-efficiency levels are not increased to any great extent.

Mark Holman, chief of the standards branch at the U.S. Department of Housing and Urban Development, which sets energy standards for homes bought with FHA- and VA-backed loans, said the provisions have a broader impact. Many U.S. builders meet the HUD standards because they don't know what type of loan will be used to purchase a house, he noted.

Sweden first included regulations for greater energy efficiency in its homes in 1977. A more stringent code, applied only to electrically heated homes, was adopted last year in the wake of a 1980 national referendum that calls for the elimination of nuclear power over the next 25 years.

"The United States faces a tremendous problem in trying to figure out whether a house is energy efficient or not," Kelly said. "In Sweden, you know what that means. It has met these very stringent codes, so it's at least that good."

As a result, R-values, a measurement of how well a structure holds its heat, have been rising steadily in Sweden. R-values range from 28 to 33 in walls and from 37 to 43 in ceilings, for example, the report said. By contrast, average walls in the United States are R-11 and ceilings are R-20, Kelly said. Windows in Sweden are triple glazed compared with the general practice of single or double glazing here.

Swedish homes are so airtight that in those built under the stricter national code adopted last year, more than two-thirds of the heat supply is drawn from so-called "free heat" sources, such as body heat, sunlight through windows and appliances, the report said. In many homes, only small heating systems can be economically justified because of the tight seals.

The problem of indoor air pollution resulting from the superior insulation is solved by providing a ventilation system that brings in fresh air, heating it along the way. American homes, by contrast, are ventilated through cracks and gaps in the structures "by imperfect construction practices," according to the report. As a result, ventilation is determined not by the homeowner but by the outside temperature and wind conditions.

Behind all the codes and regulations in Sweden is a cooperative construction industry that builds more than 90 percent of the nation's housing stock in controlled factory settings. About 40 percent of U.S. home building is done in the factory, according to the National Association of Home Builders.

The report said the difference is that Swedish factories are staffed by highly skilled workers who are flexible to accommodate the design wishes of the buyer.

"They are not minimum-wage workers," said Paul Kando, a building-technology consultant who was on the report's advisory board while he was director of product development for the NAHB. "They are master carpenters except that they no longer work with a builder's saw, but with computer-prompted equipment."

Kelly, who said that factory-built homes in the United States have a bad image, noted that, because of the controlled work atmosphere, most Swedish factories offer handsome warranties, some for more than 10 years.

The 1977 fuel-efficiency measures added between $1,200 and $2,000 to the cost of a Swedish house, while the 1984 code for electric homes added another $2,000 to $6,000. These costs are covered by the government's low-interest-loan program.

Kelly said that the extra costs are justified not only by the fuel savings, but also by added comfort. Swedish homes don't have drafts or cold spots, he said, and the air is much cleaner. "There are advantages that aren't measured by the economics of it," he said.

Kelly claimed that a monthly heating bill of $230 in the Washington area would be cut to $108 if the house followed 1977 Swedish standards, and $62 under the 1984 code. He added that Americans wouldn't have to give up any comforts because most modifications are in the walls or around the doors or windows.

Americans need help in understanding energy efficiency, Kelly said, suggesting increased regulation as an answer. He said one way would be to require a labeling system that would reveal a home's efficiency rate, similar to the Environmental Protection Agency's mileage standards for cars. Such a measure would have the added benefit of pushing the building industry into producing more efficient homes by making it attractive from a marketing standpoint, Kelly said.

American builders believe that, "If there was a market for this stuff, they'd be selling it," Kelly said. If the industry believes it "can make more money selling tiled jacuzzis than they can selling energy efficiency, they'll do it," he said.

John Millhone, head of the building research branch at the U.S. Department of Energy, would not comment on the issue of regulation, but said a voluntary labeling program "deserves some attention." Various labeling measures to help home buyers identify energy-efficient houses are in use in Colorado, Oregon, Connecticut, Florida and California.

John Crowley, director of research and development for Ryan Homes in Pittsburgh, one of the largest home builders in the Washington area, admitted that the average Swedish house is more energy efficient than the average Ryan home, but only because Sweden's climate and building regulations are tougher.

"Until customers demand higher energy efficiency and until regulatory agencies are demanding higher performance . . . you're not going to see big, sweeping changes," he said.

Sweden's strict measures have created an unusual market in which builders normally construct houses that are more efficient than required by the national code. Crowley admitted that is not the practice in the United States.

"The building code is what people build to here," he said.

Mike Bell, director of energy programs for the home builders' group, said that, because of market conditions, it probably will "take another energy crisis" to make Sweden's energy-efficiency concept marketable here.

"There gets to be a point where to increase the insulation is to price the house out of the market," Bell said. He added, however, that the average home being built in the most northern U.S. states is as efficient as Sweden's homes. But Millhone, who was the director of Minnesota's energy agency from 1975 to 1979, disagreed with Bell. He added, "There are some important things we can learn from them."

The report said Swedish government support for building research is another important tool for increasing the efficiency of their homes. Sweden's Council for Building Research, for example, spent $39 million on research in 1983, more than three times as much as HUD -- even though the Swedish home-building industry is about one-twentieth the size of the American industry.

While several builders agreed that more government research is needed, Millhone said that, if all private and public U.S. research projects were considered, "we'd look better" in comparison with the Swedish spending.

Building consultant Kando said part of the problem is that American builders and buyers look upon housing as a short-term investment. In Sweden, purchasing a home is a relatively permanent investment.