HCLS : Assessment of light distributions in simulated indoor car park – Laboratory experiments with static lighting conditions

Abstract

Purpose : In the framework of the Snellius project we investigate the possibility to improve the lighting of indoor car parks by designing and testing the dynamic lighting concept of the activity spot. A person in de car park is detected by sensors and the lighting nearby the person is set to a higher level than in the rest of the car park. The main goal of this lighting concept is reduction of lighting related energy use while improving or maintaining the level of perceived safety and comfort for the car park users. We conducted four perception experiments in the laboratory with static observers and measured the experience of comfort and safety for various photometric parameters for the activity spot. ---- Methods : The experiments were performed in a windowless corridor (L x W x H = 42 m x 3.8 m x 2.8 m) which was illuminated with 14 lamps pairs (halogen, spaced at 3 m) according various lighting distributions. Observers had to assess different activity spot conditions and a reference condition (fully lit corridor) (within-subjects design). The lighting conditions were presented randomly. The observers were alone in the corridor while statically assessing the lighting conditions and filled out a questionnaire with five statements and one open question on the experience of comfort and safety. The observers had to leave the corridor after every assessment. Three experiments (n= 13 per experiment) were conducted and 1 expert session (n=5). Results were controlled for age and gender. ---- Results : When the light spot in an activity spot is set at a lamp illuminance of 100 lx, a background with a lamp illuminance of 20 lx is the lowest light level with an acceptable experience of comfort and safety and the highest energy saving potential. The size and gradient of the light spot at the observer do not seem to determine the experience when this spot is the only activity spot in the room. When a second light spot is visible with another person in the activity spot, we found that the combination of a light spot size of 3 lamps (9 m) and a gradient of 30% resulted in an experience rating, that equalled the rating of the reference condition (100 lx for all lamps). Furthermore, we found a gender effect in experiment 3 indicating that elder women had lower experience ratings than men. It should be noted that these results only apply in the experimental setting. ---- Conclusion : Activity spots can be used to reduce lighting levels, and in potential reduce energy consumption, without compromising feelings of comfort and safety. Characteristics of valid activity spots applied in a windowless corridor were defined