Measurements of the power requirements and operating profiles of fax machines indicate significant potential for energy conservation through power management. Fax machines were active for only 3.7% of the time they were switched on; 91.8% of time at normal standby power could be eliminated by automatically switching the fax machines into a ＇sleep＇ mode after 5 min of inactivity. Such power management could realize savings of $20 per fax machine per year. In addition, 9.3% of fax transactions were halted due to transaction errors, and up to 23.8% of fared pages were cover sheets. Reducing transaction errors and cover sheet use could realize additional energy, time and paper savings, and reduce telephone charges.