Warm white versus neutral white LED street lighting: Pedestrians' impressions

The subjective impressions of pedestrians are necessary in order to decide on the appropriate colour of light to be used for street lighting. Therefore, a pilot project aimed to compare subjective evaluations of the sidewalk illumination under two street lighting installations, realised by LEDs of 3000 K (warm white) and 4000 K (neutral white), was recently conducted in Belgrade. Both installations had comparable sidewalk illuminances as well as other relevant photometric parameters. The evaluation was done through a questionnaire. A group of 139 (61 male and 78 female) respondents, all of them university students, was asked to grade both lighting installations for the sidewalk light intensity, the appearance of human faces, the colour of light and the colour rendering as well as the overall impression. According to the median values, the 3000 K LED installation was considered better than the 4000 K installation for all aspects assessed as well as the overall impression. Although the survey results convincingly showed a preference for 3000 K LEDs for this comparison, additional research is needed using a more representative sample of people and a wider range of locations before a definite conclusion can be reached.