If and when President Carter's energy proposals become law, they should inconvenience and change the District of Columbia far less than its suburbs and considerably less than many cities.

There are three reasons, according to city officials:

First, the city has no heavy industry, so its economy will not be stalled by major private businessses having to spend millions to convert from oil to coal as a source of heat.

Second, the city now has two major subway lines open. City officials expect the subway to reduce auto use, and thus to blunt the sting of any gasoline tax.

Third, the District government already has conservation programs in force, and is studying ways to help District homeowners make their homes more "energy-efficient."

Carter's original proposals, announced in April, are still making their way through Congress. They included a standby gasoline tax, a tax on cars that get poor gas mileage, a well-head tax on crude oil, an increase in the price of natural gas and a provision requiring new utility plants to brun coal rather than oil.

For homeowners, the chief improvement sought by the Carter plan was the insulation of homes in return for a tax credit.

In addition, under the Carter plan, efficiency standards would be established for home appliances, new electricity rates would be established to smooth out "peak loads" and tax credits would be given for the use of solar energy.

But aside from whatever action Congress takes on the Carter energy plan, there are also two legal stumbling blocks to some of these proposals in the District, and they are not expected to disappear without dispute.

The first is the city's air quality standards, among the most stringent in the nation. As the standards are now written, the burning of coal for heat - a cornerstone of the President's proposal to reduce oil use - is specifically forbidden.

Many buildings now have permits that make them exceptions, including 14 D.C. schools. But officials said that any significant increase in the use of coal for heat could cause serious air pollution in the city.

The second stumbling block is a provision of the city's building code that requires landlords to keep rental units at a winter minimum of 68 degrees during the day and 65 at night.

If landlords drop thermostats during a cold winter to conserve fuel and hold down their bills - a strong likelihood here, where 84 per cent of all buildings are heated by oil or gas - officials are worried that flu and lawsuits may follow.

But the more immediate worry, according to officials, is that individuals, not convinced that there is a "crisis," will continue to use energy at the levels they always have.

"We get it all the time," said Sam Starobin, director of the District's department of general services. Despite conservation efforts aimed at top officials, "some little kid in school gets cold and, bang, up goes the heat."

Another worry, not exclusive to Washington, is that even if conservation is successful, utility rates will skyrocket, producing bigger bills despite lower consumption.

The District government, the city's second biggest utility customer after the federal government, has run into exactly that situation.

For example, according to Harold T. Henson, assistant director of the bureau of repairs and improvements, the city reduced electricity consumption by 8 per cent in fiscal year 1974. It reduced consumption by another 8 per cent the next year. It shaved another 9/10 of a per cent the next year, not doing as well because several new playgrounds and facilities were built that year.

But between 1970 and 1975, the city's electric rates went up by approximately 250 per cent. So, even though the city used fewer kilowatts, its bill was bigger.

"I don't think we'll ever reach the point where we'll turn back the clock on costs," said Starobin.

But the city is doing what it can to apply a little persuasion in the right places.

The 15 largest departments of the city government have each designated an "energy officer." Every three months, the officers meet with Henson for "guidance, advice, monitoring and constant cajoling."

But Henson has no power to force conservation or energy consciousness, because each department is responsible for the "energy performance" of its buildings and personnel.

According to Starobin, the most effective way to force agencies to conserve is, for example, to reduce annual gasoline allocations in advance, then offer suggestions on how to live within the new limits.

But the District government has taken other steps, all along the lines the President proposed.

It is converting most of its automobile fleet from full-sized sedans to Chevrolet Novas. The insulation standards of its buildings - and the actual insulation thickness at many buildings - are "way beyond residential," Starobin said.

The city has installed a $55,000 computer system at three buildings to control the use of electricity automatically. It has sold or is selling more than 100 portable school classrooms - notorious energy wasters.

It has removed half the overhead light bulbs in every office and placed "Conserve" signs at every light switch. It is studying ways to carpool, and to reorganize offices so less square footage is used.

In addition, the Potomac Electric Power Co. (PEPCO) is planning a peak-load pricing experiment in which the city's 212 largest commercial customers would receive "advisory" bills showing what their bills would be if electric rates were based on the time of day at which each customer used the most electricity.

But the city employs only one person whose full-time job is to police day-to-day energy use in its buildings.

He is Malcolm Clark, chief of the improvements, maintenance planning division, and his position does not even formally exist. Clark is paid out of contingency funds allocated by several District government agencies. Next year, his salary will have to come from a Federal Energy Administration grant, for which the District has applied.

The city has another FEA grant, for $53,000, which it received to study energy conservation and related policy changes in the government and in the private sector. The grant is being administered by the office of municipal planning, with the consultation of the Mayor's Energy Task Force.

Ben W. Gilbert, director of the planning office, said the money is going toward "developing a plan for immediately implementable, significant savings by 1980." In addition, Gilbert said, studies of long-range energy savings are under way.

Gilbert said the city has formulated plans for car pooling, fringe parking and park-and-ride programs for nongovernment employees, and has studied utility rate restructuring. The city has also begun "Project Conserve," and has applied for yet another FEA grant to provide information for homeowners.

Longer range studies are examining "revised thermal and lighting programs, both public and private," waste-oil recycling, solar energy, refuse-derived fuel and variable working hours, Gilbert said.