The Effect of Fluctuating Illuminance on Visual Sensation in a Small Office

Abstract

The objective of this study was to examine occupants' responses to the visual environment influenced by changing illuminance levels and to determine acceptable tolerance ranges that did not significantly impair visual comfort when automatic dimming control systems were used. This study also investigated whether changing the light levels significantly impaired performance of a reading task given as a surrogate for a productivity test. Annoyance tests were performed under a variety of fluctuating illuminance levels controlled by a direct lighting system in a full-scale mock-up office space. Healthy 19 females and 17 males, whose ages ranged from 20 to 45 years, participated in the tests. The results of this study suggest that the degree of annoyance felt was not entirely relevant to the amount of change in illuminance, but it varied according to the task for which the illuminance was initially set up. The maximum fluctuation of illuminance controlled by automatic dimming control systems would be approximately 40% of the target illuminance in order to avoid any significant visual annoyance for office occupants. Multiple linear prediction models showed that feelings of eye fatigue, distraction, and annoyance were significant contributors to visual comfort under fluctuating lighting conditions. The reading task performance was not significantly influenced by the fluctuation of illuminance under two different task illuminance conditions.