Abstract
Lighting projects that consider parameters related to circadian light remain rare. Using controlled lighting on both photopic and melanopic levels, this study aims to simplify the design of circadian lighting projects based on traditional photometric parameters and calculations. A real classroom is used to illustrate the behavior of horizontal (visual stimuli) and vertical (circadian contribution) illuminances under different design parameters, such as the varied reflectance of walls, ceiling, and floor; varied spatial distribution curves, including the number and position of luminaires; and across the spectral power distribution of a variety of LEDs. In this work, we seek to clarify and simplify to the greatest possible extent the meaning and scope of various lighting standards while establishing simple protocols. Our results will enable designers to carry out optimized lighting projects from both the photometric and circadian perspectives.
Highlights
Most interior lighting projects must comply with a series of requirements imposed by current regulations for various spaces, including levels of illuminance, uniformity, glare, correlated color temperature (CCT), or color rendering index (CRI) [1,2], and nearly always including budgetary concerns and a desire for low energy consumption [3,4]
Such projects represent the response to the presence of intrinsic photosensitive retinal ganglion cells in humans and the nonvisual effects of light [5,6,7,8,9], and there are numerous studies that highlight the substantial influence that variations in the intensity and tone of light have on health, mood, and many other factors related to the tasks performed by individuals who work for long periods of time under artificial light [10,11]
These lighting projects that consider the possible effects of light on people, optimizing them to create the greatest possible well-being in the short, medium, or longterm, are termed human-centric lighting (HCL) projects
Summary
Most interior lighting projects must comply with a series of requirements imposed by current regulations for various spaces, including levels of illuminance, uniformity, glare, correlated color temperature (CCT), or color rendering index (CRI) [1,2], and nearly always including budgetary concerns and a desire for low energy consumption [3,4]. There has been an increase in lighting projects that include, as new criteria, temporal variations in the light, both spectrally and in terms of intensity, with which our body is familiar and that regulate the circadian cycles of our biological clocks Such projects represent the response to the presence of intrinsic photosensitive retinal ganglion cells (ipRGCs) in humans and the nonvisual effects of light [5,6,7,8,9], and there are numerous studies that highlight the substantial influence that variations in the intensity and tone of light have on health, mood, and many other factors related to the tasks performed by individuals who work for long periods of time under artificial light [10,11]. The increasing number of such projects does not correspond to the importance that circadian light should have according to relevant studies, perhaps for several reasons, including the absence of specific clear regulations; manufacturer and market inertia; unacceptable costs; a lack of appropriate and properly characterized products; and a lack of a sufficient number of trained technicians, product promotion managers, or lighting designers.
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