A number of general technologies can contribute to increased efficiency and productivity in manufacturing. These include computer control of building environments, computer control of processes or major energy-using equipment, waste-heat recovery, and adjustable-speed motors. About 79% of U.S. petroleum refineries reported using one or more of these technologies in 1994, accounting for over 97% of total process energy use. By comparison, 28.4% of the total manufacturing population used these technologies. Most frequently cited in the petroleum refining industry is waste-heat recovery (roughly 64% of the industry). [MECS 1994]