The effect of illuminance and correlated colour temperature on perceived comfort according to reading behaviour in a capsule hotel

We investigated the effect of illuminance and correlated colour temperature (CCT) on the subjective evaluation of users' reading behaviour in a narrow space (i.e. a capsule hotel). Participants (N = 18; 15 men, 3 women; mean age = 21.9 years, SD = 0.4 years; age range = 21–23 years) were Japanese university students and graduate students. Experiments were conducted within four behavioural conditions that differed in six distinct illuminance (i.e. 150 lx and 300 lx) and CCT (i.e. 2800 K, 5000 K, and 6700 K) combinations. Because of the subjective evaluation of the space using the 7-level semantic differential method, participants did not experience pressure in the experimental space when it satisfied illumination standards. Sense of security was significantly influenced by CCT rather than illumination. Higher CCT was associated with higher spatial brightness. Lower CCT was associated with a higher sense of security, restfulness, and positive feelings. Brightness, sense of security, restfulness, feelings of fatigue, and concentration were all significantly impacted by the behavioural conditions. These findings suggest that providing a user-friendly and user-controlled lighting system will likely increase the satisfaction individuals experience when staying in a capsule room.