Effect of Color Temperature and Illuminance on Psychology, Physiology, and Productivity: An Experimental Study

Abstract

In this study, we investigated the impact of the lighting environment on psychological perception, physiology, and productivity and then designed lighting control strategies based on the experimental results. The research was conducted in a smart lighting laboratory, and 67 subjects were tested in different illuminances and correlated color temperatures (CCTs). During the experiment, the physiological data of subjects were continuously recorded, while the psychology and productivity results were evaluated by questionnaires and working tests, respectively. The experimental results found that both illuminance and CCT could significantly influence the feeling of comfort and relaxation of the subjects. Warm CCT and higher illuminance (3000 K–590 lux) made subjects feel more comfortable. Productivity reached its maximum value with illuminance above 500 lux and equivalent melanopic lux (EML) higher than 150. The brain-wave and heart-rate changes did not have a close relationship with either illuminance or CCT, but the heart rate slightly increased in the adjustable lighting mode. Regardless of the initial value setting, the subjects preferred intermediate CCT (4200 K) and bright illumination (500 lux) after self-adjustment. Finally, we proposed three comprehensive lighting control strategies based on psychology, productivity, circadian rhythm, and energy-saving.

The Effect of Correlated Colour Temperature on Physiological, Emotional and Subjective Satisfaction in the Hygiene Area of a Space Station

“…Some studies found that the heart rate of participants who remained in 6000 K lighting was slightly, but not significantly, higher than during the 2700 K period, regardless of whether it was day or night for the participants [ 52 , 53 , 54 ]. Conversely, other studies have found an increase in heart rate when CCT lighting conditions were higher [ 54 , 55 , 56 ], which is not consistent with the results of the present study. This may be due to the variability between CCT lighting conditions, the task scenarios set and the selection of the participant population.…”

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“…The Pearson analysis showed a correlation between relaxed-tense mood and CCT. This result was in line with the conclusion that CCT significantly affects the relaxed feeling (Chen, Tsai & Tsay, 2022). The negative coefficient on the result means that the warmer CCT, the subject will be more relaxed and the cooler the CCT will lead to a more tense mood.…”

Impact of repeated morning bright white light exposures on attention in a simulated office environment

“…Fourth, the spectral composition of light was not changed throughout the study. Moreover, neutral-white light was chosen for task lighting instead of cold-white light (6500 K or higher), as studies have shown that this light color is perceived as more pleasant 74 , 75 . However, it can be hypothesized that light pulses with high melanopic illuminance (i.e., with more short-wavelength radiation) could have even greater effects on attention.…”