TM-30 and Daylight

An architect recently emailed me asking if it was possible to use TM-30 metrics with daylight.  My short answer was something like, “I suppose you could, but why would you?”

The long answer is that all of the TM-30 measurements (Rf, Rg, the 16 chroma shifts, the 16 hue shifts) are relative – comparing the light source in question with the reference light source.  With daylight, you’d be comparing the daylight SPD you captured at a moment in time with the CIE definition of daylight at the same CCT.  On an average day I doubt that any of the measurements would deviate from 100 by more than a couple of points.  So, using TM-30 (or CRI Ra) is like measuring a ruler with another ruler.  You’re essentially comparing one thing to a definition of itself.

Specifying Color Quality With TM-30

By now most of us have attended one or more seminars or webinars about IES TM-30 and understand that it is a method of measuring various color rendering properties of a light source and reporting those measurements.  The thing that’s been missing is a recommended set of values that set minimums, maximums and/or tolerances for the various measurements.  This has been true for two reasons.  First, TM-30 is a method and as such was never intended to set recommended values.  The second is that while the science behind TM-30 is solid, the science doesn’t offer any predictions of acceptability.

Good news!  After almost three years of research and tests around the world we’re much closer to establishing a set of recommended values.  At this year’s IES Annual Conference in Boston, Tony Esposito, Kevin Houser, Michael Royer and I will be presenting the seminar “Specifying Color Quality With TM-30”  The description of the seminar is, “This presentation will discuss several research projects which have used the IES TM-30 color rendition framework, and whose results have been used to develop various specification criteria. We will discuss UFC 4-510-01, The Department of Defense Unified Facilities Criteria for Military Medical Facilities, which has already implemented IES TM-30-15 specification criteria.”

During the seminar we’ll review some TM-30 basics, look at several research projects that are helping to establish TM-30 thresholds, and review how to use the TM-30 calculator.  Don’t miss it!

International Day of Light 2018

Today, May 16th, is the International Day of Light 2018.  It began in 2015 when the U.N. declared  The International Year of Light and Light-based Technologies.  Today, the International Day of Light is

a global initiative that provides an annual focal point for the continued appreciation of light and the role it plays in science, culture and art, education, and sustainable development, and in fields as diverse as medicine, communications, and energy. The broad theme of light will allow many different sectors of society worldwide to participate in activities that demonstrates how science, technology, art and culture can help achieve the goals of UNESCO – education, equality, and peace.

There are events around the globe related to the theme of light.  If you’re interested you can check the web site, and the sites of organizations such as IALD and IES.

Night Shift? Not Quite.

We’ve all heard about the effect blue light can have on our circadian rhythms.  It can suppress the release of melatonin, which can delay sleep and reduce sleep quality with possible long-term health consequences.  Circadian disruption has been associated with depression and increased risk of diseases such as diabetes, obesity and cancer.

Back in 2016 the AMA released a report recommending night-time outdoor lighting have a color temperature no higher than 3000 K to limit night-time exposure to blue light.  That report was quickly criticized by the Lighting Research Center and the IES, among others, as I noted here and here.  One of the key criticisms was that correlated color temperature is a poor measure of spectral content and says nothing about the amount of energy in the wavelength range that affects our circadian rhythms.  A better measurement is melanopic content, which isn’t discussed in the report.

Last year Apple unveiled a feature in their OS and iOS called Night Shift.  When enabled it causes the color of the display to become warmer in the evening.  The assumption, the same as the AMA’s, is that warmer light has less blue so it won’t impact melatonin production.

A recently published paper in Lighting Research & Technology looked at the effectiveness of Night Shift.  This preliminary study suggests that “changing the spectral composition of self-luminous displays without changing their brightness settings may be insufficient for preventing impacts on melatonin suppression.”  Even when Night Shift was used, the devices still suppressed melatonin production.  The authors noted that, “it is not known how this amount of suppression induces circadian disruption, delays sleep or affects health.  Larger, more comprehensive epidemiological studies should investigate how the long-term use of these self-luminous displays affects people, especially adolescents and children.”

While additional studies are clearly needed, it provides additional evidence that lower CCT alone is probably not enough.  With our display devices we should also lower the brightness.

IALD – News – International Association of Lighting Designers

The linked article is on the web site of the IALD and concerns Louisiana State House Bill 748 which would prohibit the use of the terms “registration” and “certification” for nongovernmental professional credentialing.  The problem for lighting designers is that it would mean we couldn’t say that we were Lighting Certified (LC) by the NCQLP or that we were a Certified Lighting Designer (CLD).

No doubt there are other professions that would also be harmed by the bill.  The next vote is scheduled for May 9th.  If you want to let them know what a bad idea this is, contact the bill’s sponsor Julie Emerson.

Source: IALD – News – International Association of Lighting Designers

Design for Color and Illumination Webinar April 19th

On April 19th Wendy Luedtke (my co-chair of the IES Color Committee) and I will be presenting a free IES webinar called Design for Color and Illumination.  Here’s the blurb from the IES site:

When developing a lighting design, lighting specifiers determine the lamp and fixture combination that best suits the design’s requirements based on many factors. While some considerations are largely technical, such as power consumption, the amount of light generated, and how light is distributed, one consideration is both technical and artistic and can be approached in a number of ways. Participants to this webinar are eligible for one (1) IES Continuing Education Unit (CEU).

The webinar is at 12 noon EDT.  Register here.

Outdoor Night Time Lighting May Reduce Crime

I’ve just learned about a study conducted last year for the New York City Housing Authority (NYCHA).  In a randomized trial 39 NYCHA sites received additional night-time lighting for 6 months, while 38 sites received no additional lighting.  The study showed these reductions in crimes:

Index crimes: 7% reduction in overall index crimes (day and night). This reduction in overall index crimes was driven by a 39% reduction in index crimes that took place outdoors at night.

Felony crimes: 5% reduction in overall felony crimes (day and night). This reduction in overall felony crimes was driven by a 30% reduction in felony crimes that took place outdoors at night.

Assault, homicide and weapons crimes: 2% reduction in overall assault, homicide, and weapons crimes (day and night). This reduction in overall assault, homicide and weapons crimes was driven by a 12% reduction in assault, homicide and weapons crimes that took place outdoors at night.

Misdemeanor crimes: No detectable change in net misdemeanor crimes in treatment communities.

The results of other studies have been mixed, but I’m not clear if they were controlled, randomized studies.

The disappointing thing, from a lighting designer’s perspective, is the data that’s missing.  The report tells us the fixture wattage and lumen output, but doesn’t tell us the area covered or measure the increased light levels.  Instead it treats light fixtures as fixed items and counts them per square block.  This method would be fine if the world had only one type of outdoor fixture, but it doesn’t  So more light is better, but it doesn’t say how much more or what the upper limit should be.

Transforming Patient Healthcare and Well-being Through Lighting

Recently, the Illuminating Engineering Society (IES) and Center for Lighting Enabled Systems & Applications (LESA) at Rensselaer Polytechnic Institutesponsored a workshop to explore pathways to define and promote the adoption of lighting systems specifically for healthcare environments.  The aim of the workshop was to initiate an important discussion among diverse stakeholders on the changes in modern healthcare interior lighting applications. The result is the release of a white paper detailing the outcomes and contributions of the participants.

Source: Transforming Patient Healthcare and Well-being Through Lighting | IES