Analysis of visual comfort and circadian stimulus provided by window design in educational spaces

Abstract

Light is the main variable which affects to the circadian rhythm, promoting up to 70% of the melatonin suppression. In comparison with the visual system, the circadian system requires more light to be activated and is more sensitive to blue light. As can be deduced, daylighting represents an ideal light source for circadian entrainment. Architectural and design features, such as window size and room reflectance, impact the amount of circadian stimulus that occupants will receive. This study aims to quantify the circadian stimulus promoted in classrooms, according to the window size and reflectance of the surfaces. A first trial is carried out, monitoring the spectral power distribution perceived by the eyes of the students according to different orientations and observer’s positions. Secondly, several simulations are developed, using the daylight simulation program DaySim 3.1 and defining a classroom model with a variable window size and reflectance. The results show the noticeable impact of the reflectance of the inner surfaces in the circadian stimulus calculation, as well as the effect of the window size.