The question asked about architects so often has been: why do they design such ugly buildings? But these days a more insistent question is being asked: why do they design such energy-inefficient buildings?

Aesthetics are always arguable. But energy efficiency can be quantified down to the Btu. The AIA Research Corp., an independent member of the American Institute of Architects family, has analyzed a sampling of buildings constructed in 1975 and 1976. It found that if the buildings had been designed with already proven and available technology, their energy efficiency could have been increased 30 percent to 50 percent.

Huber H. Buehrer, a Toledo, Ohio, architect, has journeyed around the country trying to educate his colleagues into mending their wastrel ways. Recently his travels brought him to a dreary motel hard by the Beltway in Alexandria, where he gave his two-day "energy analysis short course" for about 25 architects and the same number of engineers. The course teaches designers how to audit energy use of every aspect of a building. With this information, they can then figure out how best to retrofit an old building and build efficiency into a new one.

After two days in Alexandria, Buehrer was off to Richmond, Norfolk and finally Roanoke. Altogether he reached about 100 architects, or about one-tenth of those registered in Virginia.

Buehrer can be optimistic about his circuit-riding, but sometimes he has doubts that his students will actually apply what they learn and spread the word among their colleagues in the profession. "For a long time," he said after a day and night of teaching in Alexandria, "I thought it possible to solve the problem by educating the profession. But maybe -- I hate even to mention it -- we can't avoid federal regulation."

The potential for energy saving in building design is enormous. According to Buehrer, if all existing buildings were retrofitted with proven technology and if new buildings were designed using more current higher-yield techniques, the energy saving by 1990 would be the equivalent of 5 million to 7 1/2 million barrels of oil a day.

But only small, halting steps have been made toward this possibility. So the question reasserts itself: why do architects design such energy-inefficient buildings.

Duncan Bremer, an analyst at AIA Research Corp., says most architects "just do not spend a lot of time in continuing education. It interrupts their work." Furthermore, he said, most of them are too economically vulnerable not to cater to their clients -- business people who, more than likely, see their buildings only as a column of numbers that work or don't work.

Higher fuel prices will not necessarily force change. Building owners can deduct those higher prices on their income tax returns.

But there are signs, here and there, that old patterns are changing -- or being changed. Congress is considering legislation that would make retrofitting costs fully deductible, and thus competitive with tax write-offs for wasteful energy use. The Department of Energy is about to propose regulations that will set energy performance standards for new buildings. The AIA is starting to respond. Its local societies -- with other groups as well as unions -- are sponsoring courses like Buehrer's. The AIA has even undertaken a retrofitting of its own 6 1/2-year-old headquarters behind Octagon House on New York Avenue. Critics of the building's aesthetics may not be any happier, but the retrofitting, which cost $250,000, appears to be cutting energy costs by 40 percent. The payback period for the capital investment, AIA officials say, should be about two and a half years.

Ultimately, according to the American way, energy efficiency will come when it can be sold in the marketplace. But is that happening? Harry Hart, the former Smithsonian Institution exhibit designer, now designs and builds houses that may be the most energy efficient in the country. Hart's homes -- which have double walls, a solar orientation and sparingly placed windows -- have been featured in The Washington Post, on TV and in Money magazine. Despite all the publicity, he says, "I still don't have buyers accepting my ideas. They want modifications -- for example, a fireplace or an outside exhaust fan, both of which are energy wasteful. I'm kind of disgusted."

Does anyone still wonder why architects design energy-inefficent buildings?