Nonvisual aspects of daylight in the built environment

Abstract

This paper investigates melanopic equivalent daylight vertical and horizontal illuminances within an indoor space as a metric for the nonvisual effects of its lighting. The article is based on the findings of photobiological research and the recommendations of several institutions for the threshold values of melanopic illuminance at the eyes of users of indoor spaces, which is sufficient for the proper functioning of the circadian system. This study uses a computer workplace as an environment to investigate experimentally the applicability of melanopic daylight metrics for the practical evaluation of the circadian potential of the indoor daylight environment. The article points out a number of problems associated with the practical evaluation of vertical melanopic daylight illuminance in a specific space. The paper also outlines practical guidelines for designing facades and color treatment of building surfaces in terms of their circadian potential.