APRIL 2022 LIGHTING JOURNAL
N I T T H F I E H S S T A A N D DAR EN E
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44
STANDARDS
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Current standards for LED lighting still don’t go far enough in terms of tackling, and resolving, ongoing concerns around glare, argues Leonardo Bartoletti. He makes the case that a new approach is needed for measuring LED intensity, spectrum, photometry and spacing By Leonardo Bartoletti with Ruth Dutton
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s ILP members well know, LED street lighting luminaires have transformed how our public realm is illuminated. Yet, complaints about the feeling of discomfort they can cause, especially in terms of glare, remain stubbornly persistent. This, in turn, poses an important question: as technology improves, how can we maintain the advantages we derive from LEDs while increasing visual comfort? I intend to argue in this article that, to answer this, we need to improve not just our understanding of LED glare and discomfort but, critically, our criteria as an industry for assessing. Let me explain. It wasn’t that long ago
that the most common colour temperature for streetlamps was cool white CCT 6000K or even higher. Yes, LED luminaires are now evolving into gentler, more userfriendly forms. Yes, too, it is true that streetlamps with a neutral or warm-white colour temperature are now the most commonly used. However, it is also increasingly recognised that the speed at which we need to be adopting more sustainable LED lighting has to increase if we are to move to less environmentally harmful industry and business models. To my mind, one way this shift can be accelerated is if we review and update the calculations that are used to determine
MAX street lighting standards, such as the volume of acceptable glare created.
UNINTENDED SIDE-EFFECTS
Developed since the 1970s, in other words before LEDs were commonplace, the current calculations, I’d argue, are no longer fit for purpose for specifying the best-quality LED lighting. Nor do they ensure the safest or healthiest option is always used. The difficulty with LEDs is there are often unintended, undesirable side-effects: harshness of light, glare, uneven lighting, and hard shadows, for example. These concerns are not trivial. Such side-effects can affect mood, productivity, alertness, safety, comfort, spatial awareness and depth perception. The discomfort associated with LED glare can feed through into worries (justified or not) about artificial lighting’s impact on our circadian rhythms or general wellbeing. While no one within lighting would, of course, argue that the answer is to do away with LED – its advantages and flexibility are too great – there is an argument that we have abandoned traditional luminaires without fully updating the metrics we need properly to evaluate this new light source.
