The link below takes you to a recent LD+A Online article I wrote with Michael Royer and Jess Baker, It addresses some of the issues related to LED color names, and explains the ways colored LEDs are described, including dominant wavelength, peak wavelength, and chromaticity coordinates.
Source: Color: Shades of Gray – Illuminating Engineering Society
Today I want to talk about the lack of photometric information provided by manufacturers because the presentation of information frustrates me in two ways. The first issue is the lack of information provided. The second is the difficulty of finding real world examples of what I teach in class. What’s the value of knowing the point and lumen methods if the information needed isn’t available? It seems to be a problem that’s getting worse and I’m not sure why.
By failing to publish photometrics, manufacturers are dictating my workflow without understanding how I work and why I work the way I do. I rarely name names, but I’m going to make an exception here. Maybe a little photmetric-shaming (one of the most obscure types of shaming, to be sure!) will get manufacturers to change.
Are You a Contender?
When I navigate my way to a fixture web page and open the cut sheet my main goal is to determine if the fixture is a contender. Does it seem to have the features I’m looking for? If not I can move on. If so, the next question is, “Does it have the performance I’m looking for?” Photometrically, I’m looking for general distribution type, followed by more specific distribution information, lumen output and load, and beam angle. If those look good, I’ll scroll down the cut sheet to the photometric section to get some info to run a quick calculation in a spreadsheet that’s open on my desktop. If the fixture works in that quick calculation I’ll download the cut sheet and .ies file and run an AGI calc when I’m ready. What I’m looking for on the cut sheet, depending not the calculation, is:
For example, I recently went looking for a linear downlight. My first stop was Coronet because I know they’ve recently revamped their historically deficient cut sheets. Are the new cut sheets any better? No. The first page of the cut sheet for the LSR2, for example, now has a section labeled “Optics” (not photometrics) and gives a sort of candlepower distribution curve, but there’s only one number, which seems to be candlepower at nadir but isn’t labeled as such. A separate section at the bottom of the next page shows “Performance” in terms of watts/ft and lumens/ft for three output levels. That’s it. Any reasonable calculation of the fixture’s performance in a space requires downloading .ies files, building a model in AGI, and running a calculation. As I said earlier, that’s not my workflow. I can run a lumen method calc much faster than I can build an AGI calc and I don’t want to be forced into AGI.
Next I looked at Focal Point’s Seem 2. As with Coronet, there’s a candlepower distribution curve. The ordering matrix tells me there are four lumen outputs, and there’s a table of output, watts, and lumens/watt. A lot of page space is given to lengths and controls, but there’s nothing else about photometric performance on the cut sheet. To find any useful information I have to download .ies files and open them in Photometric Toolbox or AGI.
Finally, I looked at Acuity’s Mark Lighting. The cut sheet for the Slot 2 LED presents a table of lumens/ft, watts/ft, and lumens/watt for four output levels, but there’s no candlepower distribution curve or CU table. On the plus side, the information I want is provided, but in a separate location on the web page called Photometry & Revit (BIM). If I click on Report I find a polar candelas graph, zonal lumen summary, CU table, etc. I wish this was in the cut sheet, but at least it’s available.
I have similar complaints about other manufacturers who make fixtures I generally like: Alphabet, USAI, Day-O-Lite, and Ecosense among them.
Let Manufacturers Know
If you’re similarly frustrated let manufacturers know. If you’re at Lightair this week tell them face to face. If not, tell your reps and anyone at the factory you may know.
Last week Tony Esposito and I presented seminars at ArchLIGHT Summit in Dallas, TX. The topic was TM-30 and the deep information that it provides us about a light source’s spectrum and the resulting color rendering. CRI, of course, only evaluates fidelity – how close a light source matches its reference light source. But CRI penalizes all deviations and says nothing about the rendering of individual colors. Nor does it help us understand if the deviations from the reference are acceptable to viewers.
A small part of our demo is shown below. It illustrates how two light sources can have the same fidelity (in this case Rf of 70) but wildly different spectra that produce wildly different color rendering results. This is the great strength of TM-30, a deeper insight into the effect of a light source on illuminated objects and their color appearance – not just fidelity, but chroma shift, hue shift, and the perceptual implications of those shifts.
The video below shows the color appearance shifts. The graphic illustrates that even though the Rf is 70, the first light source renders objects in a preferred manner (Preference Priority Level of 3 or P3) and increases vividness (Vividness Priority Level of 2 or V2). At the same Rf the second source mutes colors and fails to achieve any of the Design Intents and Priority Levels specified in TM-30’s Annex E.
A reminder that Tony Esposito and I will be presenting Specifying Light Source Color Rendition three times at ArchLIGHT Summit in Dallas next Tuesday and Wednesday, the 21st and 22nd. Hope to see you there!
A very interesting article in today’s New York Times. Sustainability Advocates Ask: Why Demolish When You Can Deconstruct? – The New York Times
There’s an excellent post on the IES’s FIRES blog. It recounts some of the the history of V(λ) and our pursuit of measurements for brightness. It points out how much we’ve learned since the metrics we use today were developed, and calls for rethinking and development of new, 21st century metrics. Read it!
Source: The Test of Time – Illuminating Engineering Society
My colleague Tony Esposito and I will be giving a new TM-30 seminar and demonstration at ArchLIGHT Summit 2021 in Dallas on September 21st and 22nd. We’re working on a new, and we hope more attendee friendly, presentation and an all new set of demonstrations to explain TM-30s Annex E specifications. The demo will include, for the first time, live models of different ethnicities so attendees can evaluate the impact of of the specifications on skin tone. I hope to see you there!
Many of us on the IES Color Committee, myself included, have written and spoken about TM-30 and how to use it. I’ve written posts on this blog (click on the color rendering tag to see them all), authored articles, spoken at IES Annual Conferences, given webinars to architects and lighting designers, and assisted manufacturers in adding TM-30 data to their cut sheets. Despite our efforts, and those of others, TM-30 is still not as well understood and broadly implemented as it could be.
A recent issue of Leukos featured an excellent tutorial by Michael Royer of Pacific Northwest National Laboratory. In it, he describes the development of TM-30, color rendering fundamentals, the workings of the TM-30 calculation framework, TM-30 measures and their meaning, and more. That article is now available on the US Department of Energy’s website here. Anyone who’s unsure about TM-30 will find it immensely useful.
On a related note, many members of the IES Color Committee, myself included, can make themselves available to answer questions or present webinars to architects, interior designers, lighting designers, electrical engineers, sales reps, and manufacturers. If you’re interested, use the Contact Jason Livingston link above to send me a message. If I’m not available or the right person for your organization I’ll find someone who is.
You may recall that in 2019 the Trump administration blocked a rule intended to phase out incandescent lamps and encourage a conversation to more energy efficient models, namely LEDs. If you don’t remember the New York Times and NPR both had articles, among many others.
Last week, the Consumer Federation of America and the National Consumer Law Center, along with 24 other groups across the country, urged the U.S. Department of Energy (DOE) Secretary Granholm to implement the efficiency standard for household lighting products mandated by Congress as soon as is practicable. They claim that “Each month of delay costs American consumers nearly $300 million in lost utility savings and results in another 800,000 tons of climate changing CO2 emissions over the lifetimes of the incandescent bulbs sold in that month.”
You can read the entire press release at Consumerfed.org
Last week I was in Boston and wanted to visit the USS Constitution. The ship was closed but the visitors center was open. When I went inside and tried to read the exhibit signage, here’s what I saw:
Track lights were positioned right over the semi-gloss signs, creating terrible reflected glare. The thing is, this is so easy to avoid. In fact, someone almost has to try to create lighting this bad. Here’s how to avoid it.
