This is the VOA Special English Development Report.

A building designer in the United States has developed small, rounded homes called "superadobes." They are made from earth strengthened with cement and wire. The design of the homes is based on Iranian desert architecture. Nader Khalili was born in Iran. He used to design tall office buildings. He now has an organization in California known as the Cal-Earth Institute.

Mister Khalili says five unskilled workers can build a two-person superadobe in less than one day. To begin, they mark a six-meter circle on the ground. Then they dig out the earth in the circle to a half-meter deep.

The dirt must have some water in it. The moist earth is mixed with a small amount of loose cement and put into sandbags. Then the bags are placed around the inside edge of the hole, to a height of about three-and-a-half meters. Barbed wire placed between each level of the bags helps hold them in place. In time, the plastic sandbags will dissolve in the sun and disappear.

Mister Khalili says wood can be used as a border for doors and windows during the building process. After the structure dries, though, the wood should be removed. A mixture of earth and grass spread outside and inside of the home help finish the structure. The inside can also be painted with a mixture of milk and linseed oil to reduce the smell of earth.

A fireplace can be added for heat and cooking. Water and electric power can also be added. Mister Khalili says temperatures inside are usually a lot cooler than outside. Heat escapes through an opening in the top. Windows also help keep the structure cool. Tests have shown that the homes can be strong enough to survive earthquakes.

But the superadobes have critics. Some say the design is old and that newer housing technologies may offer better solutions in developing countries. Critics also say that some of the designs may last only about three years.

Nader Khalili says his homes can be built for less than two-hundred dollars anywhere in the world. He argues that they offer economical housing in emergency situations. United Nations officials say such homes could be used in refugee camps. Even the American space agency, NASA, has shown interest in superadobes -- for future colonies in space.

This VOA Special English Development Report was written by Jill Moss.