Luminance calculation method accounting for mesopic vision and fog penetration ability

Area of Science:

• Optometry and Vision Science
• Illumination Engineering
• Atmospheric Optics

Background:

• Street lighting effectiveness is crucial for public safety and relies on appropriate light source selection.
• Existing luminance calculations often do not adequately account for varying atmospheric conditions like fog or the nuances of human vision under low light (mesopic vision).
• LED technology offers versatile lighting solutions, but selecting the optimal correlated color temperature (CCT) for street lighting requires a refined approach.

Purpose of the Study:

• To develop and present a novel luminance calculation method for street lighting that integrates mesopic vision and fog penetration capabilities.
• To establish a scientifically-backed methodology for selecting appropriate LED light sources for urban and roadway illumination.
• To provide recommendations for LED CCT in street lighting based on diverse visibility and luminance scenarios.

Main Methods:

• A new luminance calculation method was developed, incorporating mesopic luminance calculations and transmittance calculations at individual wavelengths.
• The method was validated by evaluating six LED light sources with correlated color temperatures (CCT) ranging from 3500 K to 6000 K.
• The study analyzed the interplay between luminance, transmittance rates, and recommended CCT for LED street lighting.

Main Results:

• The calculation results demonstrate a dependency of optimal LED CCT on luminance and transmittance conditions.
• For low transmittance rates (e.g., fog), suitable LED CCT decreases as luminance increases.
• Conversely, high CCT LED lamps are found to be most suitable for street lighting under high transmittance rates.

Conclusions:

• The developed luminance calculation method provides a more accurate basis for selecting street lighting sources.
• Recommendations for LED CCT in street lighting are established, varying with specific visibility and luminance conditions.
• This research contributes to enhancing the efficacy and safety of street lighting through optimized light source selection.