Selecting monitor and wall luminance levels in office settings: An adaptive experimental study

Modern office environments increasingly feature multiple computing devices and advanced monitors, whose maximum luminance levels have risen significantly in recent years. In addition, current lighting standards place greater emphasis on the role of ambient lighting and wall (il)luminance in creating a comfortable environment. However, higher luminance levels do not inherently lead to enhanced reading comfort. Prior research indicates that reading comfort is influenced by a combination of monitor luminance and the luminance characteristics of the surrounding environment. This study examines the optimal monitor luminance levels that enhance reading comfort under fixed wall luminance conditions, as well as the optimal wall luminance levels under fixed monitor luminance conditions. A total of 25 participants (aged 21-26 years) took part in the experiment. Using the psi-marginal adaptive method, participants were given direct control to determine the luminance levels they perceived as most comfortable for reading. Four different monitor luminance levels (120, 260, 453 and 700 cd m^-2) and five wall luminance levels (12, 34, 68, 113 and 170 cd m^-2) were used as fixed luminance levels throughout the experiment. The results demonstrate that higher fixed wall/monitor luminance levels are generally associated with higher optimal monitor/wall luminance levels selected by participants. According to the European standard of lighting requirements for indoor workplaces, the minimum required wall luminance is between 24 cd m^-2 and 38 cd m^-2. For a fixed wall luminance level within this interval (34 cd m^-2), the results of this study show that the optimal luminance level of the monitor ranges from below 120 cd m^-2 to around 450 cd m^-2 with a median of 166 cd m^-2, and an IQR of [133 cd m^-2; 270 cd m^-2]. In conclusion, the findings suggest that, within standard office environments, it is not necessary to utilise monitors with luminance levels exceeding 500 cd m^-2 to achieve optimal reading comfort.