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Bi-Level light switch Bi-level controls show energy savings up 52%

Bi-level Controls for Occupancy Sensors Boost Effectiveness

In private offices, occupancy sensors save approximately 30% in lighting energy compared to traditional switches and meet energy code requirements for automatic shut-off. Adding manual bi-level control to the sensors can substantially boost energy savings.

A recent study by the California Lighting Technology Center, an independent research organization, on the value of adding manual controls to occupancy sensors in private offices, determined that increased energy savings, up to an additional 52%, are achievable when occupants can make decisions about how much light to use.

The study, funded by Watt Stopper/Legrand, a manufacturer of energy efficient lighting controls for commercial and residential use, focused on how manual bi-level lighting controls should be configured to provide the greatest energy savings and occupant satisfaction.

Researchers calculated that when both levels activated automatically, savings were 34%. When both levels remain off unless switched on, savings were at 46% (reflecting the fact that often occupants turn both, rather than one, on regardless of task needs and the amount of ambient light). However, when one level activated automatically and study participants could turn the second level of lighting on or both levels off, based on task needs and available ambient lighting, savings reached 52%.

These results indicate that the best practice scenario is to have one light level activated automatically when occupancy is detected, while the other remains off unless manually activated. And participants appreciated control of the light levels.

“The study indicates there’s still a lot of room for energy savings in new and existing buildings,” says Pete Horton, VP market development for Watt Stopper/Legrand. “If looking to maximize lighting energy savings, combining manual bi-level controls with occupancy sensing appears to offer building owners one of the highest available returns on investment."

Photo courtesy of Watt Stopper/legrand