The ability to control fire is considered one of the most important factors in expanding and developing our human ancestors’ societies. The societal importance of fire required larger and larger groups to work together in order to maintain and sustain the fire; individuals had to work together to find fuel for the fire, maintain the fire, and complete other necessary tasks. Ultimately, fire had a significant influence on the development of language and the size and social interactions of communities.
The Forum for Illumination Research, Engineering, and Science (FIRES) is the IES online space for our lighting community to openly share and discuss the latest research and innovations in illumination engineering and science. As a space for the free dissemination of knowledge and exchange of ideas, FIRES is intended to foster relationships between individuals and larger institutions, and reignite the emphasis on science and engineering in the lighting industry. Through FIRES, we hope to have a significant influence on the development and advancement of lighting.
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Editorial Disclaimer
The views expressed in articles published on FIRES do not necessarily reflect those of IES or represent endorsement by the IES.
By Ian Ashdown, P. Eng. (Ret.), FIES
Senior Scientist, SunTracker Technologies
By Michael L. Grather, CTO, LightLab International Allentown, LLC
We have all seen the wide range of new products claiming to be effective against pathogens of all sorts. Common claims range from the rather ambiguous “fights germs” to the more specific but questionable claim “can disinfect up to 40 square meters of the surface at a time.” Maybe it’s just the times we’re living in, but my first reaction is to take a very skeptical view of these claims. It also seems that I’m not the only one. My neighbor, who is not in the lighting field, asked me if I thought “these UV lights” are safe. Almost without taking another breath he followed it up by asking “… do they actually work?”
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By Manuel Spitschan
Around 20 years ago, a new type of cell was discovered in the human retina, the fine layer of tissue at the back of our eyes that enables us to see the world in its colourful detail. These cells, the intrinsically photosensitive retinal ganglion cells (ipRGCs), are sensitive to light independent of the canonical photoreceptors, the cones and the rods.
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By Brian Liebel
IES Director of Standards and Research
This article is an expanded version the article found in the 50th Anniversary issue of LD+A, July 2021, providing additional background, more references, and personal insights by the author.
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By Ian Ashdown, Senior Scientist
SunTracker Technologies Ltd.
Nighttime light pollution is sadly familiar to all of us. While our grandparents and great-grandparents may talk fondly of seeing the Milky Way in their youth, with thousands of stars scattered across the dark summer sky, we are mostly content with seeing a few dozen stars through the never-ending dusk of urban and suburban skies.
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Authors: Ellen Kathrine Hansen, Mihkel Pajuste; Aalborg University, Copenhagen
In this new dynamic lighting approach, the sky type and daylight inflow are taken into consideration actively, bringing the dynamic office lighting to life instead of only meeting the static illuminance requirement through artificial lighting.
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By Ian Ashdown, P. Eng., FIES
Senior Scientist, SunTracker Technologies Ltd.
A word of caution: I am going to be annoyingly pedantic here, but with good reason. The lighting industry has a century-long history of introducing unfamiliar technologies using familiar terminology. We later come to regret our choice of words when it becomes necessary to express precisely what we mean.
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It seems that every month there is a new metric proposed to quantify the performance of light sources, particularly with respect to spectral properties. One of the latest examples is Average Spectral Difference (ASD).
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Right after receiving my PhD, I took a position as a research scientist at the National Research Council Canada (NRCC) in Ottawa. It was a very good decision. The NRCC was populated and managed by scientists and engineers who understood their collective role as providing a solid foundation for decision-making by Canadian industry and politicians.
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By Jennifer Long, PhD
Jennifer Long Visual Ergonomics, Katoomba NSW, Australia
In his editorial “Is there a science of lighting design?” Peter Boyce observed, “the lighting designer who can deliver a solution that matches peoples’ preferences is likely to be successful.”1 But how does one accurately establish a person’s preferences? Do lighting preferences equate to the needs and requirements for the visual environment?
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By Ian Ashdown, P. Eng., FIES
Senior Scientist, SunTracker Technologies Ltd.
Germicidal lamps emitting ultraviolet-C (UV-C) radiation have been in use since the 1930s (Wells and Wells 1936). These are most commonly low-pressure mercury-vapor discharge lamps, which are basically fluorescent lamps without a phosphor coating and fused quartz rather than borosilicate glass bulbs. They emit monochromatic radiation mostly at 254 nm, a wavelength that is very effective in disrupting the DNA of viruses, bacteria, and other pathogens.
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By Travis Longcore
From the position of wildlife, the best artificial light at night is no artificial light at night.
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By Colleen Hufford, LC, IES
Kelly Seeger, MSc, LC, IES, LEED AP
Signify
Arguably, the biggest challenge we face (as an industry) is how to successfully apply circadian science to garner real, demonstrable benefit for people. As manufacturers, we are challenged with figuring out the technical specifications—the recipes, so to speak—to create lighting products and systems that deliver circadian benefit.
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By Jason Livingston, Michael Royer, Tony Esposito
Hopefully, you have heard of TM-30 by now. ANSI/IES TM-30-18, IES Method for Evaluating Light Source Color Rendition provides a robust suite of metrics that convey much more information than any previous attempt at characterizing color rendering.
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By Naomi J. Miller, PNNL; Anne (Lia) Irvin, PNNL
The candela and the lumen are units based on one form of human spectral sensitivity, characterized with the weighting function known as V(λ), which was derived under a very narrow set of experimental conditions by multiple researchers, and the results awkwardly combined in 1924 to produce the familiar photopic response function [Sharpe and others, 2005].
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By Ian Ashdown, Senior Scientist SunTracker Technologies
Whereas human vision relies on five opsins as photoreceptors, most plants have a wide variety of photopigments that are responsive to optical radiation from 280 nm to 800 nm. Beyond photosynthesis, plants rely on this radiation to control photomorphogenesis, phototropism, shade avoidance, and both circadian and circannual rhythm entrainment.
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By Mehlika Inanici, Ph.D.
The dynamic intensity and spectra of daylight inform human beings about the passage of time and weather, produce the best color rendition, regulate circadian rhythms in all living beings, and facilitate sustainable lighting practices.
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Naomi Miller’s essay “The Elusive Discomfort Glare Metric” highlights a number of questions within the lighting community about the causes of (and, hopefully, the cures for) discomfort glare, as well as some recent progress from the International Commission on Illumination (CIE) toward practical metrics that address solid-state lighting (SSL) systems. Playing on the title of her essay, this comment hopes to demonstrate that the path to appropriate metrics for discomfort glare may require expert navigational skills (elusive), but ultimately it is not a path to nowhere (illusive).
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By Sam Berman, HFIES
Senior Scientist Emeritus Lawrence Berkeley National Laboratory
and
Robert Clear, FIES
Staff Scientist (Retired) Lawrence Berkeley National Laboratory
During the past two decades, the lighting community has come to recognize that retinal photoreception extends beyond rods and cones, and includes a small number of intrinsically photosensitive retinal ganglion cells (ipRGCs) with their own unique spectral sensitivity. In this dialogue we provide a simple method for incorporating the metrological consequences of this sensitivity into lighting practice.
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By Naomi J Miller, FIES, Pacific Northwest National Laboratory
In The Elusive Discomfort Glare Metric, Naomi J. Miller, FIES describes how the IES Discomfort Glare in Outside Nighttime Environments Committee is working on changing that.
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By Darcie Chinnis, PhD, PE, IALD, MIES, LEED AP BD+C, WELL AP
Lighting is often described as a balance of engineering and art – where creative aspirations are balanced with functional needs and ultimately often limited by energy code requirements.
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By Douglas Steel, Ph.D., NeuroSense
The purpose of this article is to evaluate from a biological standpoint the rationale for the establishment of a Circadian Lighting standard put forward by UL under the direction of Dr. Mark Rea of the Lighting Research Center at Rensselaer Polytechnic Institute. This critique is limited in scope but also applies to utilization of the Circadian Stimulus (CS) calculator also developed by the LRC.
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By Ian Ashdown
Whether you call it “circadian lighting,” “biologically effective lighting,” or some other name, the principle is the same: the color and intensity of light can be used to regulate the timing of our biological clocks, or “circadian rhythms.” For architects and lighting designers, this is an opportunity to provide healthy and comfortable environments for building occupants.
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By Eric Bretschneider
For better or for worse, the lighting industry commonly associates the lifetime of LEDs and LED-based lighting products with L70 – the amount of time for the lumen maintenance of an LED-based device to reach 70% of its initial value. Admittedly, the failure of other components, particularly those that provide power to LEDs, are more likely to determine the overall lifetime of an LED-based component or luminaire. However, only lumen maintenance is considered here.
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By Dr. James M. Gaines
Flicker and stroboscopic effect are presently hot topics in lighting, along with other subjects like blue light (subject of a recent FIRES article). A National Electrical Manufacturers Association (NEMA) standard, NEMA 77, addresses measures for temporal light artifacts (TLA), which is an umbrella term covering both flicker and stroboscopic effect (as well as phantom arrays. The NEMA metrics for flicker (short-term flicker indicator, Pst) and stroboscopic effect (Stroboscopic Visibility Measure, SVM) are both based on experiments done with many human observers, to measure average human sensitivity to flicker and stroboscopic effects.
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By Christopher Cuttle, MA, PhD, FCIBSE, FIESANZ, FIESNA, FSLL
This procedure is based on the concept that there is real advantage to be gained from changing the illumination metrics used for specifying, measuring and predicting lighting applications so that they relate to people’s responses to visible effects of lighting in indoor applications.
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By Eric Bretschneider, Ph.D
How often do we hear about the dangers of blue light from LEDs? Such discussions inevitably include statements about “the intense blue peak” in LED lighting and the potential for damage from the massive amounts of blue light present in LED lighting.
The whole argument sounds plausible enough when we look at the spectrum of a typical white LED. The spectrum below is for a typical white LED with a CCT of 4,000 K at levels that approximate a typical commercial or retail environment (400 lux). The isolated peak in the blue clearly stands out, but does it really represent a massive dose of blue light?
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By Ian Ashdown, P. Eng. (Ret.), FIES
Senior Scientist, SunTracker Technologies Ltd.
Numerous medical studies have shown that exposure to blue light at night suppresses the production of melatonin by the pineal gland in our brains and so disrupts our circadian rhythms. As a result, we may have difficulty sleeping. It is therefore only common sense that we should specify warm white (3000 K) light sources wherever possible, especially for street lighting.
True or false?
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By Douglas Steel, PhD
Founder and Chief Scientific Officer of NeuroSense
These are transformational times for the lighting industry. The cost of LED-based products has dropped dramatically. At the same time, increased sophistication and capabilities of tunable LED arrays, controls, and sensors now enable the commissioning of platforms that can precisely control light intensity, correlated color temperature, and relative spectral content.
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By Robert F. Karlicek, Jr., Ph.D.
The Internet of Things (IoT) is a hot topic these days, driven by the explosion of low-cost sensors, microprocessors, and wireless communications to provide new types of services for consumers and businesses.
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