Saving energy, money, flatland for agriculture, and possibly living healthier are some of the advantages of underground homes, Gideon S. Golany, university research professor of urban design/planning, said.

Underground homes have at least 30 feet of earth above them, contrasting with earth-sheltered homes, which are just surrounded by earth, said Golany. The 10 meters of earth cut heating and air-conditioning costs by as much as 75 percent - the temperature of the dwellings is around 45-50 degrees Fahrenheit in winter and 65 degrees in summer.

"Heat hitting earth takes one season to process to interior walls of the dwelling because the sun's heat influences earth very little each day(1-1.5 inches)," said Golany.

Thus, the heat of summer warms the home in winter and the cold of winter cools the home in the summer, he said.

Most of the homes built in the United States have been earth-sheltered. Often the homes are built and then earth put on top of them, which serves to insulate rather than allow for the seasonal process of cooling and heating, said Golany.

John Carmody, deputy director of the Underground Space Center at the University of Minnesota, is not sure underground homes will ever catch on in the United States because they are so unconventional and because there does not seem to be the energy crisis that existed 10 years ago. However in Europe, where agricultural land is scarce, many underground home communities do exist, he said.

There is evidence to suggest living underground is healthier. First, Chinese researchers have found those living underground live longer than their above-ground counterparts. Second, chickens raised below-ground give greater quantities of larger eggs, Golany said.

Third, "Recuperation rooms of hospitals in China are built below-ground and I discovered that the client saves 25-30 percent time healing external wounds," Golany said.

Underground homes are not a modern invention, however. People in China and Tunisia have lived in underground homes for thousands of years and many live in them today, he said.

The two types of underground homes Golany studies are what he terms "pit" or "cliff" dwellings. "Pit" dwellings are constructed by digging a large hole and then digging individual cave-like dwellings. "Cliff" dwellings are constructed by digging out sides of a cliff.

Golany said he recommends cliff dwellings be built today because they allow for more light penetration and do not use flatland neccessary for agriculture, he said.

Golany said a problem to be solved before underground homes will be widely used is psychological. People have many negative connotations associated with the underground, including a feeling of claustrophobia. However, in many high rise office buildings today there is only one wall with a window on it, which is very similar to cliff dwelling models, he pointed out.

Carmody said he thinks the immediate future of underground home technology will be in nonresidential structures such as office buildings and schools.

There are many uses for underground space besides living space. Oranges are stored underground in Turkey and grain has been stored underground for hundreds of years in China, Golany said.