Optimal tunnel lighting design in aspect of lighting quality and energy performance

Abstract

The lighting quality and energy performance of tunnel lighting systems based on different tunnel lighting designs are investigated to identify the optimal tunnel lighting design. Furthermore, the lighting qualities of various mounting heights and luminaire spacing are discussed based on different tunnel lighting parameters. Thereafter, the luminaire spacing is optimized for various road widths and luminaire power. Finally, the effects of the surface reflectance of the wall, ceiling, and road are compared in terms of the lighting quality and energy performance. The results indicate that the mounting patterns have a significant effect on the average luminance in the single-row arrangement. A symmetrical system with ceiling mounting can provide remarkable overall and longitudinal uniformities. Reducing the mounting height from 7 m to 5.5 m results in greater average luminance and better TI of about 11 % and 45 % respectively, but the overall and longitudinal uniformities are degraded by 20 % − 30 % and 30 % − 45 % respectively. In addition, reducing the distance between the luminaires from 30 m to 10 m improves the total tunnel lighting quality, i.e., 67 % of average luminance, 55 % of overall uniformity, 75 % of longitudinal uniformity, and 60 % of TI. In addition, the road, wall, and ceiling surface reflectance have a dominant effect on the lighting quality. A tunnel surface with low reflectance degrades the lighting quality, resulting in minimum luminaire spacing and poor energy efficiency.