Investigation on the impacts of natural lighting on occupants' wayfinding behavior during emergency evacuation in underground space

Abstract

Some cases and studies show that occupants tend to evacuate to bright passages in an emergency evacuation. In an underground space, reasonable natural lighting configurations can effectively reduce the lighting energy consumption under conventional and emergency conditions. Furthermore, natural light was considered one of the indicators of the direction of an exit and has potential impacts on human emergency evacuation wayfinding behavior. Because designers currently use natural lighting in underground space mainly to improve environmental quality, the impact of natural lighting on safe evacuation or energy consumption is rarely considered. Related research has rarely been carried out quantitatively. Our research intends to explore the influence of natural light on occupants’ wayfinding behavior during emergency evacuation in underground space. It attempts to answer two questions: 1) Whether natural light is one of the main factors affecting occupants’ emergency evacuation wayfinding behavior in an underground space, and how does it compare to other factors. 2) Is the influence of natural light on evacuation wayfinding related to the brightness of lighting? The research uses highly immersive virtual reality to establish a research method with ecological validity and controllability. Through two controllable VR experiments, it is shown that in more than 10% of cases where passages were presented with natural light, signs or familiar exits and the three passages offered conflicting directional guidance, research participants chose natural light over the others and in more than 30% of cases, research participants chose the natural light passage when natural light and signs provided conflicting directional guidance. These results confirm that natural light is an important environmental factor affecting occupants’ emergency evacuation wayfinding behavior in underground space. At the same time, no significant correlation was found between the brightness of the light and the wayfinding influence. Our research results can provide quantitative data on the natural light evacuation guiding effect in underground spaces to provide a basis for evacuation performance assessments and develop better evacuation models and safety evacuation policies.