The Necessity for Multi-Spectral Simulations of the Indoor Non-Visual Luminous Environment: A Simplified Annual Approach

The difference between the functioning of the human non-visual and photopic systems has elicited the need for complex in situ measurements or time-consuming multi-spectral simulations to accurately predict the non-visual luminous content of the indoor environment. As such methodologies are time-consuming, the aim of the present study was to determine whether such complex methodologies are needed. The issue was studied through simulations of four cardinally oriented identical offices located in Ljubljana, Slovenia. Each was studied using orange, grey and blue walls. Diurnal luminous conditions were studied under clear, hazy and overcast skies on December, March and June 21st. The non-visual content was evaluated using novel metrics, the Autonomy of Circadian Potential and Circadian Autonomy, which assess temporal circadian luminous content. Diurnal results were used to construct climate-based spectral months to evaluate the monthly non-visual potential of the studied offices. Furthermore, simulations addressed the question of whether the requirements of the non-visual system might contradict the visual comfort of indoor environments. The results show that compliance with non-visual requirements for indoor spaces with spectrally neutral surfaces or those in shades of blue could be assessed using photopic methodologies. However, this is not true for spaces characterised by orange and red materials.