Forum for Illumination Research, Engineering, and Science (FIRES)

Forum for Illumination Research, Engineering, and Science (FIRES)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.

Figure 1. Germicidal response function for ultraviolet radiation (adapted from CIE 2003).

Ultraviolet Radiation Terminology

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. Read More

Spectral Similarity as a Measure of Naturalness?

Spectral Similarity as a Measure of Naturalness?

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). Read More

Figure 2.

Applying circadian-effective lighting — Understanding the 3 Ps

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. Read More

Control room after refurbishment. Photo courtesy of Schiavello.

Unifying the Art and Function of Light in the Built Environment – The Collaborative Roles of Visual Ergonomists and Lighting Designers

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? Read More

Designing a UV-C Germicidal System

Designing a UV-C Germicidal System

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. Read More

Figure 1

On the Use of Summary Metrics of Light Spectral Characteristics to Assess Effects of Artificial Light at Night on Wildlife

By Travis Longcore

From the position of wildlife, the best artificial light at night is no artificial light at night. Read More

Figure 2. Gartner’s Hype Cycle aligned with Moore's Technology Adoption Cycle.

The Slope of Circadian Enlightenment

By Colleen Hufford, LC, IES
Kelly Seeger, MSc, LC, IES, LEED AP

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. Read More

Figure 1.

Using TM-30 to Improve Your Lighting Design

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. Read More

M/P Figure 1

M/P ratios – Can we agree on how to calculate them?

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]. Read More

Figure 1. Typical HPS lamp spectral power distribution versus McCree curve.

Specifying LED Colors for Horticultural Lighting

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. Read More

Figure 2.

Focusing on Daylight Spectra

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. Read More

Discomfort Glare Metrics: Elusive, but not Illusive: A companion piece to The Elusive Discomfort Glare Metric

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). Read More

Figure 1.

Simplifying Melanopsin Metrology

By Sam Berman, HFIES
Senior Scientist Emeritus Lawrence Berkeley National Laboratory
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. Read More

The Elusive Discomfort Glare Metric

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. Read More

Light + Quality

In Defense of Lighting Quality

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. Read More

Figure 1.

Circadian Lighting: a Neuroscientist’s Perspective

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. Read More

Figure 1.

Circadian Lighting: An Engineer’s Perspective

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. Read More

An Intuitive Metric for Lumen Maintenance

An Intuitive Metric for Lumen Maintenance

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. Read More

Figure 1: An example of the stroboscopic effect, measured with a short duty cycle and 100% modulation

Concerns in the Age of the LED: Temporal Light Artifacts

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. Read More

The Lighting Design Objectives (LiDOs) Procedure

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. Read More

A Reality Check on Blue Light Exposure

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? Read More

Melanopic Green The Other Side of Blue

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? Read More

The Science of Light and Health: How to Interpret the Claims That Underlie Medical and Wellness Effects

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. Read More

Lighting and the Internet of Things

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. Read More

Figure 3 – Infrared “smudge” (see text for explanation).

The Science of Near-Infrared Lighting: Fact or Fiction

By Ian Ashdown, P. Eng. (Ret.), FIES, Senior Scientist, SunTracker Technologies Ltd.

There is a common-sense argument being presented in the popular media that since humans evolved under sunlight, our bodies must surely make use of all the solar energy available to us. Given that more than 50 percent of this energy is due to near-infrared radiation, we are clearly risking our health and well-being by using LED lighting that emits no near-infrared radiation whatsoever. Read More

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