C. R. Skidmore and his wife, Hazel, moved into their new two-bedroom home three weeks ago and, except for the girl who rode over their house on a horse, they say not much is new in their lives.

Gerald Hayes says he has no second thoughts about his new six-bedroom home, but then he has't had to mow the roof yet.

And Wayne Penny, who expects to move into his new home with the cathedral ceiling and fireplace laterlthis year, is already trying to get used to having an "up door" rather than a front door.

All three of their homes, like the homes and workplaces of a growing number of Americans, are underground - where it is warmer in winter, cooler in summer and where, when the Television is off and everybody's stopped talking, it is as quiet as a tomb.

High energy costs that have driven people up the wall are now driving them underground in schools, libraries, homes and soon, a Minnesota prison. "Returning to the soil" is taking on a whole new meaning as skylights replace windows, as turf substitutes for shingles and as acenic views remain above invisible buildings.

From a library at Harvard to two o elementary schools in Fairfax County, Va., from housing subdivisions in Pennsylvania and California to a new Fort Worth library that will open this month, buildings using heps of dirt to protact them from the elements are being built at dramatic pace. "We've got a very difinite boom," declares William F. Kneeland, a consulting engineer who has assisted a number of underground home owners here.

Advocates of earth-covered housing, many of whem will gather in Forth Worth today for a four-day conference sponsored by the U.S. Department of Energy, see underground houses as rich in energy savings so valuable to a nation dependent on foreign supplies for almost one-half of its oil.

The use of earth to reduce energy consumption can range from vast amounts - it takes nine feet to virtully eliminate the need for heating and cooling incertain parts of Texas - to thinner blankets or berms for just substantial savings.

"With nine feet of earth on top, the heat from summer finally gets down here in winter, when you want it," said Frank L. Moreland, director of the Fort Worth conference."

The practice and theory is that there is substantial energy savings," said Ray Sterling, director of the Underground Space Center at the University of Minnesota (which has absolutely nothing to do with interplanetary travel). "We should be able to save 50 to 75 percent - it depends on what you compare it to."

"It was a calculated risk," Skidmore a retired Federal Aviation Administration supervisor, said of his decision to put a $41,300 eight-inch reinforced concrete house in a knoll, under four feet of earth.

"But it is the house of the future. We are in an energu crisis." Despite 40 degree nights and 90 degree days. Skidmore and his wife have yet to use the heater or the air conditioner, and the house remains constantly comfortable.

Here in Oklahoma City area, the number of underground houses will double this year to 30, says Kneeland, and will probably double again next year. Minneapolis-St. Paul is going underground even quicker, with perhaps 50 to 100 homes to be completed this year, according to Sterling.

Moreland, an architecture professor at the University of Texas at Arlington , has designed one house already under construction and has 11 more to begin work on this summer.

Minnesota also has a new $22.2 million maximum security prison for 400 inmates, with three sides in a hill, about to begin construction, and California will have a new underground state office building in Sacramento.

To be sure, there is nothing new about living in the earth, but today's structures - some with high ceilings, expanses of windows and bright colors - are hardly like the dank, ark caves of early man or the sod houses of the tornado-prone plains. One man here is so sure that moisture can be prevented in the underground house he's building that's he's including a swimming pool inside it.

For Gerald Hayes, underground living has meant seeing northbound motorists from Texas, California, Arkansas and Louisiana detour off Exit 91 of Interstate 35 to gawk at what is behind that stone-faced rambler with the skylights in the Open field.

"It's a different feeling," he says with some understatement. The house is quier, only a little darker away from the front, with its spacious windows. Hayes has hung murals of outdoor scenes on the walls of bedrooms under the skylights. Flourescent lighting takes over at night.

Moreland says that underground houses can be built at prices comparable to similar abovefround houses but with substantial savings in continuing energy costs and exterior maintenance.

The new $4.2 million Fort Worth library lies beneath two city blocks downtown. It was less costly than aboveground proposals, and the city expects $3 million to $5 million in energy savings over the life of he building.

There is the question of how many people are ready for living underground. Penny hints that his wife is not all convinced that their newhomw is the house of the present, let alone the house of the future.

But the only trouble Skidmore has had, he says, eas the kids dropping things down his chimney into the firstplace, so he modified the chimney. And then there's the quiet. "If a person does't like the quiet," said Skidmore, "then he doesn't want an underground home.

"Listen," he says, but there's nothing to hear. "The wind's blowing a ton out there but you can't hear it."

Indeed, you can't, and he likes it like that. After all, Skidmore's two previous homes had both been splintered by tornados, and he's looking forward to the next one, when he can sit 14 feet below the surface and wonder what his neighbors are doing.