Assessment of public lighting systems considering mesopic vision

Abstract

The objective of this research was to evaluate public lighting systems installed in a concrete pathway considering the effects of mesopic vision. The light sources evaluated were high-pressure sodium vapour, metal halide and LED. The quantitative evaluation was based on in-situ measurements of the illuminance and luminance levels and computer simulations. The qualitative aspect included the application of questionnaires to local users. It was found that the energy savings could be up to 53% when replacing metal-halide lamps with LEDs. As for the qualitative analysis, the LED lamp was the one that received the best evaluation, followed by the metal halide and finally the high-pressure sodium vapour. The LED provided a greater sense of security to people, although the illuminance level provided was 31% less than that of the sodium vapour lamp. The research confirmed the effects of mesopic vision, i.e. when light sources with higher S/P (Scotopic/Photopic) ratio were used, the luminous perception and efficiency of the systems increased. Based on the analysis performed, it was noticed that the use of LEDs to light a concrete pathway was the best option in terms of energy savings and safety.