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Bi-level Office Lighting

Bi-Level Office Lighting Field Test

Many commercial-use building codes require occupancy sensors for lighting or manual control of light levels. Studies by California Lighting Technology Center and others indicate that additional energy savings may be achieved through a combination of occupancy sensors and bi-level lighting. This project evaluated that scenario for enclosed, individual offices. We investigated electricity use and economic performance and compared to single-level, manual switching. The study found that operation of bi-level switches to optimize electricity savings led to a scenario which was preferred by 64 percent of occupants. Since most office workers now tend to work on computers a large proportion of the time, lower light levels are required than in the past.

The maintenance staff reported that the required equipment - including wall switch sensors, ceiling sensors, and bi-level ballasts - were easy to install and commission. We observed that energy savings are highly correlated with operational schedules. This indicates that education of the occupants or users of controls will likely influence overall efficiency. For example, automated illumination to 50 percent of maximum light level is encouraged. The economic performance of bi-level switching was found to be most favorable in a new construction or major remodel situation.

Project Team
WSU Energy Program: Mary Matteson Bryan, Jack Zeiger, Doug Koenen, and Cindy Wills
California Lighting Technology Center: Cori Jackson and Pedram Arani
WSU Energy Program: Shelley Kirk-Rudeen and Gerry Rasmussen



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