Manufacturers may conduct a number of energy-management activities to improve the efficiency of energy use. In the glass industry, the top four reported activities in 1994 included energy audits, purchase of electricity under special rate schedules (e.g., interruptible or time-of-use rates), equipment or facilities modification to improve direct machine drive, and equipment or facilities modification to improve facility lighting. Overall, about 53% of the glass population reported engaging in at least one energy-management activity. These reporting establishments were responsible for about 71% of the total glass industry energy use in 1994. [MECS 1994]