Subjective evaluation of luminance distribution for intelligent outdoor lighting

Abstract

A large number of physical dimensions and different criteria make choosing the optimal luminance distribution for outdoor lighting difficult. The optimisation becomes even more complex for light-emitting diode-based lighting installations that can be intelligently operated, providing different luminance distributions around a moving traffic participant. This study aims at establishing the main subjective factors for the assessment of the luminance distribution of an intelligent light-emitting diode-based outdoor lighting installation for pedestrians. Semantic-differential scales and Likert scales have been used to identify subjective impressions and to find the main factors for the optimisation of the control of the luminance distribution. Our results reveal two factors that need to be considered when assessing intelligent outdoor lighting installations: a major factor that is related to the subjective feeling of well-being and a minor factor that is related to the physical properties of the environment.

How Much Lighting is Required to Feel Safe When Walking Through the Streets at Night?

“…Additionally, the study covered a relatively large number of observation points (257), in 10 different neighborhoods, in three different cities-all of which contribute to higher generality. It should also be noted that previous studies involved relatively small numbers of research subjects, and evaluated relatively small numbers of lighting sources, thus, falling short of representing different urban settings, larger populations and population subgroups [1,29,33,57]. The present study effectively addresses these drawbacks and may lead the way for future studies to be conducted elsewhere.…”

Road lighting and pedestrian reassurance after dark: A review

“…There is some evidence that distributing light to highlight natural objects rather than artificial objects enhances reassurance. 65,66 Finally, two studies demonstrate that spatial distribution needs to consider the location of the pedestrian, 63,64 for example, a possible preference for brighter lighting in the immediate vicinity of a pedestrian, and thus the need for dynamic control over spatial distribution. Spatial distribution is the least wellinvestigated characteristic: there is a need to repeat past studies to extend and confirm the findings, and to consider how the lighting designer might respond to these issues.…”

“…The results from three studies [63][64][65] indicate that alternative approaches to spatial distribution should be considered. Haans and de Kort 63 compared three variations of spatial distribution using a row of five luminaires ( Figure 6): Conventional (all set to the same light output), ascending (low light level at observation point, increasing light level further away) and descending (high light level at observation point, decreasing light level further away), with all three designed to provide the same overall amount of light.…”

“…A further study of spatial distribution was carried out by Viliunas et al 64 who used a similar experimental design but with less extreme variation in illuminance. In this study, test participants stood under the first of three lamp posts in an outdoor location, these spaced at 30 m distances.…”

Assessment of pedestrian discomfort glare from urban LED lighting

“…Zhu et al 10 found no effect of the number of sources on discomfort glare either; they used a vertical panel of LEDs to simulate road lighting in the laboratory. Pedestrian studies also suggest that observers feel the discomfort glare due to one luminaire at a time 5 , and judge the lighting quality with respect to the luminaire closest to them 11 .…”