A chorus of bird trills enhances the pastoral atmosphere of William and Betty Ogden's ''dream house.'' Sunshine illumines white ceiling and walls, offset by handsome oak beams and tile floors.
Inner airiness aside, however, theirs is not the ordinary clapboard cottage with a white picket fence.
The quest for energy efficiency over the last few years has produced some strange mutations of ''home, sweet home.'' The Ogdens, who came here from Pennsylvania, were not to be outdone by their neighbors' double-wall and ''envelope'' abodes, so they ingeniously opted to burrow underground for a genuine earth-shelter home.
''I've heard several comments about 'Flat Roof,' '' Mr. Ogden says smiling.
''If anyone comes skimobiling, they'll fly off the roof and land in the front yard,'' Betty adds.
''You ought to put up a sign: 'Caution - steep drop-off,' '' Charles Ficke, a designer with the Newport-based Sakonnet Housesmiths, suggests. ''The people that live on (nearby) Green End Avenue love it because it doesn't obstruct their view. When equipment comes in, and then it doesn't rise up above the foundation, they ask questions.''
Mr. Ogden, an engineer with Computer Science Corporation, had long hoped to settle in New England and build a small, low-maintenance house. Four years of research convinced him of the virtues of living ''in the earth,'' as he puts it.
By pure coincidence, the former owner of the land, Dan Paquette, president of Sakonnet Housesmiths, shares an enthusiasm for superinsulated, passive-solar dwellings, and welcomed the challenge of subterranean building.
''Everybody gets experimented on,'' Mr. Ficke says of the company's clientele.
''The main concern is water. You always think in certain lines of defense. First, how to shed surface water, keeping it away once the water does seep into the ground, so that it doesn't build up pressure and crack the concrete.
''And second, the actual waterproofing of the house.''
In response to the initial threat, 11/2 inches of stone surrounds the house, carrying rainfall and any additional ground water directly down to the foundation wall, where a perforated drainpipe guides it far beyond the two side retaining walls.
Next, 4-by-6-inch sheets of rigid foam insulation sandwiched between the fiberboard, are coated with bentonite, a volcanic clay, which withstands freezing and swells to 10 times its size when wet, averting voids.
Ethylene propylene diolene monton also covers the roof, which is engineered to handle twice the weight of more conventional roofs.
''It won't blow away,'' Mr. Ogden quips.
The R-40 rating accorded the house would have been impaired by fiber glass, Mr. Ficke allows, which leaves gap and humidity seepage. As further precautions, 4 inches of concrete underlie floor tiles, and below the concrete are 2 inches of Styrofoam, 2 inches of crushed stone, and earth, Ogden says, beaming.
''People really don't get the feel for the structure,'' Mrs. Ogden says with awe. ''It's a fortress.''
The real test came shortly after the Ogdens moved in last May. Torrential June rains harried New Englanders.
''I tell you, I was holding my breath all through that rainstorm,'' Ficke confides.
''The only moisture we've had in the house is what comes up from the concrete as it's curing,'' Ogden affirms. ''I have no worries now.''
Taking advantage of a natural convection system, the solarium's casement windows, overset by removable wooden blinds in the summer, draw the prevailing southwesterly breezes in and up through the skylight. Conversely, in the winter the 10-inch-thick concrete wall blocks the cold while the dense oak beams store up the day's heat, which is released at night and when the day is overcast.
An overhead radiant-electric-heat system provides the sole backup heat.
''A lot of research recently has proven that human comfort is determined not so much by ambient air as by the surface areas around,'' declares Ficke, a Rhode Island School of Design graduate, as he feels the floor around him.
''In May, the sunlight only penetrated about a foot, but it should wash across the tiles in the wintertime.''
As the seasons progress, no rugs will interfere and the furniture will be moved back from the windows.
Incredible brightness predominates through the succession of two bedrooms and their accompanying baths, a study, and combined living and dining room, plus a kitchen, pantry, laundry room, and workshop. Skylights are scattered around the top of the house.
''It's not like being underground at all, is it?'' Ogden asks. ''And there are no nails or bolts holding this structure up,'' he adds as he points out the scarf joints that identify the Sakonnet Housesmiths' trademark of post-and-beam construction.
''We can talk to each other from almost any part of the house,'' Mrs. Ogden says with approval.
Acrylic exolyte, cheaper than glass, serves as windows in the bedrooms, with inner air spaces as insulation.
''When you're building an energy-conservation house, you have to look at all the angles,'' Ficke declares. ''No trim to paint, no roof to reshingle,'' he adds.
The cost of the house, 10 to 15 percent higher, on the whole, than more conventional designs, should be compensated for by the savings in heat and maintenance.
''Next winter will be interesting,'' says Ogden.
''I seem to feel that most people see the house as an idiosyncrasy. They're still viewing it with some skepticism. Then, turning to Mrs. Ogden, he asks: ''You still have some skepticism?''
''Indeed I do,'' she responds. ''I've had ambivalent feelings from time to time. Give me a couple more years and I'll be able to give a more enthusiastic response.
''A little Cape Cod with windows on all sides is fine with me, but you never know what will happen when your husband is an engineer.''