The Measured Energy Savings from Two Lighting Control Strategies

The energy-saving benefits of two lighting control strategies -scheduling and daylighting-were investigated at demonstration sites in two large commercial buildings. A continuously dimmable lighting control system was installed at the Pacific Gas and Electric Company Building in San Francisco, and an on/off switching system was installed at the World Trade Center in New York City. By automatically scheduling the operation of the lighting systems to conform with occupancy patterns, lighting energy consumption was reduced 10-40 percent. Several scheduling techniques were investigated, and the influence of switching the zone size on energy savings was examined. Using photoelectrically controlled lighting systems, which switch or dim lighting in accordance with available daylight, the energy consumed for lighting in daylit areas was reduced to 25-35 percent. The influence of clear and overcast conditions on the energy savings associated with daylight-linked controls is discussed.