The ancient Greeks and Romans experienced an energy crisis in their urban environments. In turning to solar energy, they moved toward what today we call sustainability. We are on that same path today as fossil fuels become scarce. At about this time, the Greeks began to build their houses facing south, designing them so that the low winter sun entered the houses, providing heat, and the higher summer sun was partially blocked, cooling the houses.


Recent excavations of ancient Greek cities suggest that large areas were planned so that individual homes could make maximum use of solar energy, which was a logical answer to their energy problem. Nevertheless, moving toward improved design of homes and residential buildings to conserve energy remains an important endeavor. The rate of increase in energy use consumption leveled off in the early 1970s.


Today, U.S. industry consumes about one-third of the energy produced. The reason we have had higher productivity with lower growth of energy use is that more industries are using cogeneration and more energy-efficient machinery, such as motors and pumps designed to use less energy. Some people commute more than an hour by car to get to work, while others ride a bike, walk, or take a bus or train.