An algorithm implemented in the MATLAB system has been developed for calculating the Rsp factor as the S/P ratio of luminance at night and day conditions and selected on the basis of literature analysis the actual CIE mesopic vision model for calculation of mesopic values. We propose a complex approach to determine these mesopic values, based on the measured emission spectra of the luminaire in absolute units, using the program developed by us in MATLAB and using the program of calculation and design of street lighting Light-in-Night road (LIN). The last one, loading all the known characteristics of the lighting installation and asphalt surface, calculates illuminance and luminance in this or that place of the roadway in the direction of the vehicle driver. As a result, it was possible to determine the mesopic luminance for LED street lighting fixtures with different correlated colour temperature Tcp. For example, for a correlated colour temperature of 5000 K, a mesopic luminance 9 % higher than daytime luminance was obtained. For this option, due to a possible decrease in the normalized luminance by the same percentage, we have established a possible reduction in the number of lamps by 5 pieces per kilometre of the track and energy savings by 9 % while meeting the standards and maintaining the necessary uniformity of illumination of the road class B2. 1. Ilyina, E.I. Outdoor LED lighting of highways and city streets [Naruzhnoye svetodiodnoye osveshcheniye dlya avtomagistraley i gorodskikh ulits] // Semiconductor lighting engineering, 2010, # 4, pp. 50–55.
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3. CIE 191: 2010 Recommended System for Mesopic Photometry Based on Visual Performance.
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9. Swarnendu Das, Sangita Sahana, Biswanath Roy. Experimental Assessment of WLED Lamp Performance for Area Lighting. Application under Mesopic Photometry System // International Journal of Computer Sciences and Engineering, 2019, Vol. 7(18), pp. 213–218, E-ISSN: 2347–2693.
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• mesopic vision
• spectral luminous efficiency
• S/P ratio
• outdoor lighting