| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 248261 | Building and Environment | 2013 | 16 Pages |
•A complete analysis of the characteristics of daylight in a classroom was carried out.•Melatonin suppression during the day was calculated from spectral measurements.•Melatonin suppression depends on spectral irradiances detected at the eyes.•Reflectances of interior and exterior surfaces modify the spectrum of daylight.•Daylight-electric light integration is necessary for visual and non-visual purposes.
Light induces not only visual responses but also non-visual effects, indeed it affects performance, mood, attention and influences the synchronization of the biological clock. Duration, timing, intensity and the spectral power distribution of the light that reaches the eyes can have influence on human circadian rhythm and consequently on health. Given the important impact of the non-visual responses on people wellbeing, developing a model that allows lighting designers to predict them is a fundamental goal.In this paper a case study is reported: a series of measurements were carried out in a University classroom in order to study daylight and electric light characteristics and also their impact on the human circadian system by calculating melatonin suppression. The results obtained show that not only the intensity but also the SPD of the light received by the eyes plays a significant role on circadian response and the spectral characteristics of internal and external surfaces influence the SPD and therefore the CCT of the light that hits the eyes. Although the working behavior of the human circadian system is not completely understood, the results obtained give the designers new points of view to better evaluate lighting quality and its implications in indoor environments.
