Saving Energy with Highly-Controlled Lighting in an Open-Plan Office

Abstract

An installation in a Federal building tested the efficacy of a highly-controlled, workstation-specific lighting retrofit. The study took place in 86 cubicles in an open office with low levels of daylight. A direct/indirect pendant luminaire with three 32 watt lamps, two DALI ballasts, and an occupancy sensor provided both task and ambient light for each cubicle. All three lamps turned on and off according to occupancy on a workstation-by-workstation basis. Field measurements taken over the course of several months demonstrated 40 percent lighting energy savings compared to a baseline that represents a typical Federal building retrofit; the baseline has a lighting power density of 8.9W/m² (0.83W/ft²) and no advanced controls. A photometric analysis found that the installation provided higher desktop light levels than the baseline did, while an occupant survey suggested that occupants preferred the lighting system to the baseline.

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