The phrase ‘human-centric lighting’ seems to be everywhere nowadays. I have seen it used to describe everything from bathroom lights and adjustable desk lamps to installations in large hospital wards, multi-storey office blocks and streetlighting.
Much of what is said is confusing and sometimes contradictory. Now, at last, some experts have given their initial opinion.
As many of you will know, the CIE (the International Commission on Illumination), is the body that sets lighting standards globally. Many of its recommendations are then taken up by national and regional bodies and incorporated into their standards.
A lot more research needs to be done before firm recommendations with quantitative values can be given”
Following a conference in the UK last month, the CIE has issued a short statement entitled Non-visual effects of light – recommending proper light at the proper time. These ‘non-visual’ effects are the influence of light on our circadian rhythms, alertness, sleep patterns and so on.
While the CIE says that knowledge in this field is still ‘premature’, it goes on to say that ‘observations in laboratory and application studies show beneficial effects on human health and performance’. There is general agreement that the non-visual effects of light exposure depend on the spectrum, intensity, duration, timing and temporal pattern of the light exposure. However, they also say that a lack of understanding of the link between the light stimulus and the resulting non-visual response ‘seems to make tailored light application for a desired lighting effect impossible’.
In other words, if someone’s selling a you a lighting product that they claim will have a particular non-visual effect, take it with a pinch of salt.
To give further guidance to interested parties, the CIE will be issuing two new publications. TN003 gives guidance on how to quantify the stimulus of non-visual input in to the human photoreception system (including a ‘calculation toolbox’ to facilitate consistent results and allow comparisons with other research), while TC 3-46 WD focuses on identifying gaps in current knowledge.
In summary, a lot more research needs to be done before firm recommendations with quantitative values can be given about so-called human-centric lighting.
Alan Tulla is Lux's technical editor, and an independent lighting consultant