Lit environments that promote health and well-being

The beneficial effects of light on human non-image forming processes are subject to much research interest and are outlined in this article. Known mechanisms of impact include those on the circadian timing system, the arousal system and the affective system. An indication is made that it is important to consider the characteristics of the light field not just the light source when making recommendations concerning light of certain spectral quality. What types of light field are people exposed to on a regular basis and can these lit environments be considered beneficial? How much do these lit scenes differ in terms of spectral composition, as well as in light distribution patterns and illuminance levels, from those conditions that are currently suggested for optimising occupant health and wellbeing? A representative set of natural and built lit environments were identified ranging from seascapes/landscapes to an urban square and various interior architectural environments. A photometric and colorimetric snapshot was measured during the midday hours, to replicate the visual field as viewed from the perspective of the observer. The measured spectral irradiance of light received at the cornea was converted into derived lighting metrics that are the subject of current recommendation: relative sensitivity curve ( V λ), vertical/horizontal illuminance ratio ( E_v/E_h), cylindrical illuminance ( E_c) and circadian stimulus. The data were analysed to demonstrate that the indications are that more natural lit environments are expected to be beneficial. Discussion follows about the relative importance of spectral composition, intensity and light distribution within the visual field and how these might combine to optimise our health and wellbeing.

Practical application: Architectural and engineering designers are being encouraged to devise environments that promote human health and wellbeing. New lighting metrics are being suggested and this article seeks to indicate how effective these metrics are in their ability to characterise these lit environments.