Subjective responses to different light sources. A study on light preferences and comparison of standard light measures with human individual estimates

This study aims to evaluate how people perceive different lighting systems that determine same illuminances on a working plane and with equal CCTs, specifically addressing subjective evaluation of brightness and agreeableness either of ambient and on visual tasks and effects on mood and alertness were also evaluated. The impact of these light sources on the circadian system was also determined in order to have a complete set of data concerning non visual responses, this method is likely to be revised in the future since the working of the circadian system is not completely understood but at the present time it is one of the most accurate approaches because it takes into account the contributions of rods, cones, ipRGCs and of the spectral opponent blue - yellow channel. More tests with different light sources are already in the making with the final goal of achieving a deeper knowledge of the non visual responses working and therefore being able to develop design guidelines.