Selecting lighting system based on workers’ cognitive performance using fuzzy best–worst method and QUALIFLEX

The present study aimed to evaluate different illumination systems in the control room of a power plant and decide on the optimal illumination system in terms of the operator’s cognitive performance. This study was conducted on a control room, consisting of 16 operators. The cognitive performance and sleepiness of the subjects were evaluated under three illumination systems: fluorescent lamps (230 lux); fluorescent lamps and LEDs (415 lux), and LEDs (210 lux). The weights of the criteria determined by the FBWM and systems were ranked using the QUALIFLEX. In the morning shift, the simple cognitive function (FDST) and the complex cognitive function (BDST) indices for the fluorescent and LED-illumination system showed the best values. In addition, in the evening shift, the FDST index for the fluorescent and LED-illumination system and the BDST index for the fluorescent illumination system showed the best values. Results related to the weight of each criterion indicated that BDST with the weight of 0.665 is the most important criterion, and then FDST, with the weight 0.2, was placed at ranks 2. The results of this study showed that the best cognitive performance for control room operators provided by combined fluorescent and LED-illumination systems in the morning and fluorescent system in the evening. It is suggested that more appropriate conditions should be provided for individuals in terms of cognitive performance by adding LEDs to the traditional fluorescent systems in the control rooms and setting the appropriate time for the use of LED lamps.