Getting Control of Energy Costs.
It's a well-documented fact that properly controlled daylight promotes comfort and performance. To achieve energy savings, electric lights must be turned off (either manually or automatically) when sufficient daylight is available. Automatic systems tend to result in greater energy savings over the long run versus manual control.

Adding remote sensors, individual controls, and task lighting can greatly reduce electricity costs. Lighting controls save energy costs by dimming or turning electric lighting off when they are not needed. Control strategies are based on occupancy, daylight, schedule, or a combination of these. Lighting control strategies are most successful when people can easily understand how they work. Regularly scheduled maintenance of control equipment will improve the long-term success of the system. Maximum energy savings can be achieved when both daylighting controls and occupancy sensors control the lighting system. Here's a brief overview of lighting control hardware available:
Daylighting Controls
Occupancy Sensors
High Bay Controls
Networked Controls