Energy of earth, fuel of ancients: two oil substitutes

Only barbarians, wrote Aeschylus in "Prometheus Bound," live in "deep sunless caves in the ground, like ants!" -- and not in houses turned to face the sun. Solar architecture became popular in ancient Athens when it suffered a critical energy shortage -- the land was denuded of trees to fire silver smelters. In modern Greece, high oil prices have caused a similar reaction: thousands of rooftops now sport solar hot-water collectors.

By 1985 or soon after, Greece expects 2 percent of its energy needs to be met by solar power, one of the highest rates in the world. The reason is simple: The sun-kissed country enjoys an average of eight cloudless hours a day, double that in most of Europe.

Solar's popularity took off in 1976, when government credits helped many hotels to buy collectors. Today at least nine manufacturers sell units in Greece. The number of collectors has doubled every year.

Greek homes average about half the use of hot water of American homes. Thus they can get by with the small rooftop storage tanks. The cost of the collectors is about $30 a square foot. An investment of about $800 suffices for most homes and apartments, and offers a 3- to 10-year payback period.

Nearly half the units sold in Greece are made by Calpak, a company of about 100 workers owned by British Petroleum. Last year's sales of $5.3 million were a jump of 40 percent over the year before, giving the firm its first year of profits, manager George Michaloyannakis says.

To introduce more advanced technology, such as photoelectric cells, the National Energy Council has begun contracting with European firms to build "solar villages" on Kithnos island, in an Athens housing project, and in a Peloponnesian town.

Also, architects will soon be given literature on "passive" solar, such as the French "Trombe" wall, a black "thermal storage" wall that faces south with a double-pane glass in front of it. In Athens, passive solar could cover 70 percent of both heating and cooling needs.

Meanwhile, archaelogists continue to research solar use in ancient Greece. Floor plans found at Olynthos, Delos, and Prience reveal houses built with the sun's heat in mind.

"We need to copy the ancient Greeks," says Helen Gratsia, the energy council's architecture specialist.