Identifying relationships between daylight variables and human preferences in a climate chamber

Interactions between human beings and the built environment are mediated by physiological and psychological stimuli, which may interfere in the perception and satisfaction related to indoor comfort variables. The study aims to explore the relationship between daylighting features and possible impacts on humans in regards to lighting preferences. The influence of different daylighting configurations, glazed façade orientation and season of the year on lighting preferences in human beings was evaluated by means of tests in a rotating climate with monitoring of environmental variables, developed by the Karlsruhe Institute of Technology, Karlsruhe, Germany. The sample, n = 16, is composed of German male students (height SD = 1.80 m, SD = 0.06; body weight SD = 80 kg, SD = 8.9; and age SD = 24.9 years, SD = 3.6). Under controlled thermal conditions (PMV approx. ±0.5), participants remained in two office-like environments over 5 h (8:00 am to 1:00 pm - local time) three days in a row, for three seasons of the year, totaling nine days of data collection per participant. Definitions of glazed façade orientations for the experimental rounds were done by means of computer simulations. Objective variables were measured by spectroradiometers at desk height, with sensor h = ca. 0.90 m, and comfortmeters. Preferences of daylighting features was assessed by a questionnaire with Likert-scale alternatives, administered online at 8:50 am, 10:30 am and 12:30 pm. Objective and subjective data were analyzed statistically (Spearman's rho, rs), suggesting possible correlations between lighting preferences and objective variables, including: E (lx), CCT (K), DWl (nm) and the circadian metric a_cv (circadian action factor).