Achieving Energy Savings with Highly-Controlled Lighting in an Open-Plan Office

An installation in a Federal building tested the effectiveness of a highly-controlled, workstation-specific lighting retrofit. The study took place in an open-office area with 86 cubicles and low levels of daylight. Each cubicle was illuminated by a direct/indirect pendant luminaire with three 32 watt lamps, two DALI ballasts, and an occupancy sensor. A centralized control system programmed all three lamps to turn on and off according to occupancy on a workstation-by-workstation basis. Field measurements taken over the course of several months demonstrated 40% lighting energy savings compared to a baseline without advanced controls that conforms to GSA's current retrofit standard. A photometric analysis found that the installation provided higher desktop light levels than the baseline, while an occupant survey found that occupants in general preferred the lighting system to the baseline. Simple payback is fairly high; projects that can achieve lower installation costs and/or higher energy savings and those in which greenhouse gas reduction and occupant satisfaction are significant priorities provide the ideal setting for workstation-specific lighting retrofits.