Experimental results from a major demonstration of an advanced lighting energy management system at the World Trade Center are presented. The energy-saving benefits of automatically scheduling the operation of the lighting system to conform to occupancy patterns are examined. The energy saved by scheduling was measured by comparing lighting energy consumption without scheduling to consumption with scheduling. The benefits of a variety of switching scheduling are compared and the relationship between energy savings and sector size discussed. Using a loose automatic schedule with 1000 ft2 zones, lighting energy consumption was reduced by 30% relative to baseline consumption. With a tighter schedule, energy consumption was reduced 36-37%. Based on a simple economic analysis, scheduling is shown to be a cost-effective strategy for reducing energy consumption in buildings.