A new method for building on hilly sites is being promoted here by a firm called Architerra Inc.

David P. McKittrick, president of Architerra and its parent company, Reinforced Earth Co., said the firms have the exclusive license in the U.S. for a system developed in France. The firm helps builders prepare hilly sites for construction.

The system is energy-efficient because earth is placed against sides, the rear wall and on the roof of structures -- as well as under the floor, McKittrick said. He said the earth insulation helps units stay cool in summer and warm in winter.

A civil engineer who has headed Reinforced Earth for eight years, McKittrick said that firm has seven offices. It has been working on projects that include retaining walls for construction of the I-66 highway in Northern Virginia. The system, he said, is a less expensive alternative to the use of total concrete construction for walls and supports.

McKittrick said that the residential application of Architerra will enable licensed builders and deveopers to sculpt land to form individual building sites and create terraces formed and stablized by Reinforced Earth construction techniques.

"We will work with builders on site planning and provide materials," he added. He said U.S. construction costs are estimated to be $40 to $50 per square foot of house space.

No Architerra houses have been built in this country but thousands of earth-sheltered houses have been built by individual owners. McKittrick said.

The Architeterra program is being used on a hillside in France near Nice, where a 47-unit project is under construction. McKittrick said other small housing projects are planned near Paris an Madrid.

French architect-engineer Henri Vidal, who developed the Architerra concept, uses his Reinforced Earth system to stablize and shape the site. Reinforced Earth is described as a construction material formed by the association of fractional soil with linear metallic reinforcements.