The use of wood in ancient Rome is somewhat analogous to the use of oil and gas in the United States today. The homes of wealthy Romans about 2,000 years ago had central heating that burned as much as 125 kg (275 lb) of wood every hour. Not surprisingly, local wood supplies were exhausted quickly, and the Romans had to import wood from outlying areas, eventually from as far away as 1,600 km about 1,000 mi.
Optimistic energy forecasters estimate that eventually we may meet approximately one-half the electrical power needs of industry through cogeneration. The average first-law efficiency of only 50% illustrates that large amounts of energy are currently lost in producing electricity and in transporting people and goods. Innovations in how we produce energy for a particular use can help prevent this loss, raising second law efficiencies. Ironically, buildings constructed to conserve energy are more likely to develop indoor air pollution due to reduced ventilation.
In fact, air pollution is emerging as one of our most serious environmental problems. Potential difficulties can be reduced by better designs for air-circulation systems that purify indoor air and bring in fresh, clean air. Construction that incorporates environmental principles is more ex- pensive owing to higher fees for architects and engineers, as well as higher initial construction costs.