Research into the Influence of Lighting Modes on Human Performance Considering Daylighting: Survey and Experiment

Cities located north of the 60th parallel (Helsinki, Stockholm, Oslo, St. Petersburg etc.) are among those with a low amount of daylighting per year. The study aims to find the relationship between daylighting and electric lighting in terms of its influence on human performance, attention, and general psychophysiological state. The length of daylight hours is significantly reduced in late fall, winter, and early spring. The short length of daylight hours usually affects the well-being of people living in northern cities. The study is provided by parallel methods: an online survey and an experiment to implement a comprehensive approach. The lack of daylighting had a significant impact on the psychophysiological state of respondents in an online survey. The respondents noted a decrease in work performance, apathy, sleepiness, and lethargy in the winter season. In the spring season, the respondents described their condition as satisfied, happy, good, and highly active. The negative aspects of the lack of daylighting were noticed both by the inhabitants of the cities on the 60th parallel to the northern latitude and by the inhabitants of the more southern cities (48th parallel to the northern latitude). In the experimental part, static lighting with increased horizontal illuminance (4000 К, 700 lx) and dynamic lighting (with scheduled changes) were compared. The analysis of the experimental data showed that under static lighting the participants noticed a high concentration of attention during the day. At the end of the workday, they felt tired (headaches, tension, sore eyes). In the dynamic mode with the CCT change, the participants noticed that with the warm CCT they felt more relaxed, while with the cold CCT the concentration of attention increased. The participants rated dynamic lighting higher than static one. Dynamic lighting also has a positive effect on mental performance, selectivity of attention, and anxiety.