Integrative lighting

distinctions between circadian metrics, standards and certifications, and user satisfaction

Abstract

Research on the non-visual effects of light demonstrates that traditional lighting requirements, which focus solely on visual performance, are inadequate for ensuring health and well-being. This study compared the circadian metrics Equivalent Melanopic Lux (EML) and Circadian Stimulus (CS), calculated from experimental data collected in a field study involving participants (n=16) in a climate chamber in Karlsruhe, Germany (49.0069° N; 8.4037° E), under various light exposure conditions and in accordance with current standards and certifications. The analysis assessed the consistency of light exposure conditions with user satisfaction and physiological responses during the exposure period. The findings indicated that, while the two metrics generally converged, there were notable divergences, particularly regarding the invariability of CS across different types of light exposure and differences in the minimum daily requirement for circadian stimulation. Analysis of the field data revealed inconsistencies between satisfaction with the lighting environment, physiological responses (as indicated by changes in skin temperature during the experimental sessions), and the evaluated metrics. The primary contribution of this study is the verification of the consistency of the metrics recently introduced by the Commission Internationale de l`Eclairage with field data and user satisfaction.