Gillian Isoardi

EVALUATING VISUAL COMFORT IN OPEN-PLAN OFFICES: EXPLORATION OF SIMPLE METHODS FOR EVALUATION AND PREDICTION

As changes to building design increase the presence of daylight in the office environment, there is an increased need to account for and manage resulting potential visual discomfort. The efficient and accurate prediction of glare is an ongoing process, and the applicability of thresholds for the classification of glare in field settings is still being evaluated. This study assesses the effectiveness of measured and simulated lighting metrics in distinguishing uncomfortable lighting conditions in a sample of long-term open-plan office occupants in a subtropical setting. Evaluated metrics both under and over-predicted glare. Implications for further examination of thresholds in field settings and the prediction of glare at the design stage are discussed.

Night-time driving visibility associated with LED streetlight dimming

New LED streetlighting designs and dimming are being introduced worldwide, however, while their cost savings are well established, their impact on driving performance has received little attention. This study investigated the effect of streetlight dimming on night-time driving performance. Participants included 14 licensed drivers (mean age 34.2 ± 4.9 years, range 27-40 years) who drove an instrumented vehicle around a closed circuit at night. Six LED streetlights were positioned along a 250 m, straight section and their light output varied between laps (dimming levels of 25%, 50%, 75% and 100% of maximum output; L25, L50, L75 and L100 respectively; at 100% average road surface luminance of 1.14 cd/m2). Driving tasks involved recognition distances and reaction times to a low contrast, moving target and a pedestrian walking at the roadside. Participants drove at an average driving speed of 55 km/hr in the streetlight zone. Streetlight dimming significantly delayed driver reaction times to the moving target (F3,13.06 = 6.404; p = 0.007); with an average 0.4 s delay in reaction times under L25 compared to L100, (estimated reduction in recognition distances of 6 m). Pedestrian recognition distances were significantly shorter under dimmed streetlight levels (F3,12.75 = 8.27; p = 0.003); average pedestrian recognition distances were 15 m shorter under L25 compared to L100, and 11 m shorter under L50 compared to L100. These data suggest that streetlight dimming impacts on driver visibility but it is unclear how these differences impact on safety; future studies are required to inform decisions on safe dimming levels for road networks.