Complete evaluation of daylight characteristics in working environments

Allowing an adequate entrance of daylight in working environments is extremely important to achieve energy savings and also to ensure users' wellbeing and health. For example light is linked to the entrainment of the circadian system which regulates the timing of biological processes inside our body (circadian rhythms). To keep a 24h cycle, the human circadian system needs to be synchronized every day by an adequate exposure to light. The importance of keeping a 24h cycle lies in the link between circadian disruption, which happens when the circadian system's period is not 24 hours, and health diseases. At the present time there is still much to discover about how the circadian system works, but it is known that its response to a light stimulus depends on light's intensity, SPD, and also on the duration and timing of exposure. Therefore to evaluate the circadian impact of a light stimulus in indoor environments it is necessary to analyze its characteristics at users' eye level. This paper reports the results of measurements carried out in three offices, with different exposures, located in Naples (Italy) during different seasons (winter, spring, summer and autumn). Moreover the Irradiance Toolbox developed by Lucas et al. [8] was used to predict the photoactivation of the different photopigments in the human eye