Unless you're cheating on President Carter's request that offices and home thermostats be turned down to 65 degrees to save fuel, the freeze that is easing on the outside may appear to have moved indoors.

But the chill that is on everyone's mind is partly psychological.

British homes and offices rarely reach above 65 degrees, yet Americans, who are more used to home temperatures of 70 and even 75 degrees, are finding the cold a hardship. "The 65-degree level is tolerable," explains Dr. Elbert Phelps, professor of medicine at Georgetown University, "but it takes some getting used to."

According to suggestions offered by doctors, South Pole explorers, utility experts and housing authorities, ground rules for keeping warm inside the house are similar to those for being out in the cold.

Keep moving. Being active burns calories and generates body heat.

Pile on the layers, starting with a T-shirt to trap the heat and absorb the dampness.

Wear a hat indoors. Blood races to the head when it's cold, draining blook, and thus warmth, from other parts of the body.

The thinnest layer of fat is in the feet, nose, knees and fingers, so keep them covered. Going barefoot is a particularly bad idea at this time. Wear socks in your slippers.

Goose or duck down comforters work like down jackets, trapping air between the feathers to enhance the heat. But layers of covers, including coats or bedspreads used as blankets, are helpful.

Although the legend of applying Vaseline to the knees for added protection from the cold is indeed a myth, lubricating the skin is essential in cold weather.

"In winter there is no humidity so we need to compensate for the evaporative process that is drying the skin and causing chapping, rashes and the like," warns dematologist Dr. Philip McNaughton.

Take a moderately warm bath - hot water causes additional drying - pat dry then apply a lubricant such as cream, McNaughton suggests. Additionally, the use of any emollient such as Chap Stick or Vaseline is helpful. "It's like applying a protective wax coat to a car." McNaughton says.

Hot drinks are helpful but liquor is not, insists Dr. Karl Wipplinger of George Washington University. "Alcohol drains the heat from the body."

Eating, in spite of the instant calorie intake, is not likely to help you feel any warmer. "But fat people tolerate the cold far better than the skinny," says Phelps. "It's like wearing an extra coat."

Charles Krautler of the Washington Gas Light Co. warns against supplementing heat by leaving a gas oven on. "Not only is it likely to damage control mechanisms, but it is a fire hazard," he said. He advises taking advantage of all available solar heat, keeping shades up and blinds open on windows facing the sun.

Electric ovens are equally hazardous when used as sources of household heat, says Doris Newcombe of PEPCO. Leving an oven unattended overnight is a serious fire risk she adds.

The D.C. Department of Housing and Community Development has portable boilers on standby for emergency heat, according to spokesman Stephen Johnson. Any citizen not being provided sufficient heat should contact the complaint section of the Neighborhood Improvement Administration (724-4441/4443/4438), advises Johnson.

Landlords who comply with Carter's decree risk getting themselves chastized, even fined. A current D.C. housing regulation, section 2407, requires year-round residential temperatures of at least 65 degrees at night, but 68 degrees, three degrees higher than the President's request, from 6:30 a.m. until 11 p.m.