Assessing the Impact of the Indoor Light Environment of Office Facilities on Multidimensional Human Responses

This study investigates the effects of adjustable indoor light variables (illuminance and correlated color temperature [CCT]) typically found in office environments on human physiological, psychological, and cognitive responses. An experiment involving 72 participants was conducted, producing 360 data points. Each participant was exposed to 5 of 18 light environment conditions, which combined different levels of illuminance and CCT. Human responses were measured through skin conductivity, heart rate variability (SDNN, RMSSD, LF/HF ratio), preference, visual comfort, fatigue, work speed, and work accuracy. Correlation and multiple regression analyses were performed to evaluate both the direct effects and interrelationships among the variables. The results showed that psychological responses were most sensitive to light conditions. Illuminance significantly influenced visual comfort and fatigue, while both illuminance and CCT affected preference. Although physiological responses and work performance showed no direct statistical significance with light conditions, they were significantly correlated with psychological responses. These findings suggest that psychological responses may serve as mediators between light environments and other human reactions. Therefore, a more integrated evaluation framework is needed for light design. This study emphasizes the importance of considering psychological well-being in indoor light and provides practical implications for advancing human-centric light design in smart office environments.