Luminous flux transfer from multiple light sources considering scattering in smoke layer

The visual environment in a fire significantly influences evacuation behavior, such as perception, walking speed and route selection. Luminous exit signs and emergency lighting systems are necessary for ensuring adequate floor illuminance and clarity of evacuation routes. However, smoke would severely obstruct visibility and induce the difficulty of evacuation, especially for occupants who are in unfamiliar buildings.

In this study, luminous flux transfer in smoke-layered environments was investigated through model experiments and simplified calculating models. It was observed that for small light sources relative to smoke layer thickness, attenuation of direct luminous flux and increase of indirect luminous flux on the floor level as increasing smoke density are similar. It was found that indirect flux mostly depends on luminous flux scattered once within the smoke layer when the product of optical smoke density and layer thickness was approximately 0.35 or less. The study summarized the importance of considering scattered luminous flux affected in fire evacuation strategies to enhance visibility.