Biophilic analogous patterns for light-responsive architecture during polar night: Examining the photobiological effects of electrical lighting on surface colour configuration

Abstract

This paper investigates occupants' photobiological responses of biophilic analogous patterns such as electrical lighting and surface colour configuration during dark periods in northern architecture. Biophilic design establishes that the integration of nature-inspired architectural strategies could positively impact occupants’ photobiological responses to enhance well-being in locations with limited daylight access. Photobiological responses are indicated on image-forming (IF) and non-image forming (NIF) effects. IF relates to visual outcomes, reflected on vision and visual tasks, and measured in photopic units. NIF relates to non-visual outcomes such as the biological process of circadian clock stimulation and measured in melanopic units. Limited research addresses the impact of electrical lighting combined with surface colour (SC) configurations to optimize minimum lighting requirements at photopic and melanopic levels in an architectural setting. This research therefore examines eight surface colour configurations tested under three different luminaire positions set at warm, warm-white, and white correlated colour temperature (CCT). The variables generated 72 scenarios, which were captured through high dynamic range images (HDRi), analyzed, and post-processed to display false colour maps and values of illuminance, melanopic-Equivalent Daylight Illuminance (melanopic-EDI) and spatial colour temperature. Results demonstrate the spatial diversification generated by electrical lighting to different visual tasks and circadian stimulation over a day. The study also proved that several coloured surfaces and luminaire settings can generate similar photopic and melanopic lighting conditions despite their perceived spatial colour temperature. This research highlights the photobiological adjustment of biophilic coloured lighting ambiances provided by electrical systems in northern latitudes compromised by extreme photoperiod.