We’ve known for a while that the day was coming, and now it’s here. Effective yesterday retailers will no longer be permitted to sell most incandescent lamps (which includes halogen lamps) in the U.S. There are some exceptions for things like bug lights, but not many.
Replacement lamps for sale now must produce at least 45 lumens per watt, which is easily achieved by LEDs but impossible with incandescents.
The Department of Energy estimates that consumers will save about $3 billion per year. ( Of course, this assumes they buy quality lamps that don’t fail within a year, which is a real problem with off brand, and even some name brand, lamps.)
As part of the conversation around Diversity, Equity, Inclusion, and Respect there’s been a lot of discussion about color rendering and skin tone. I recently heard one speaker say something like, “We know that historical SPDs are racist.” I don’t think that’s accurate or helpful. Here’s why.
Since the development of the fluorescent lamp, the first priority for lamp manufacturers has been maximizing efficacy – getting the most lumens per watt. That’s still largely true today, even though LEDs are so efficient that there’s a lot of room for other considerations. An exclusive focus on efficacy inevitably results in poor color rendering, so the second priority has been acceptable (not maximized) color rendering. In other words, manufacturers have tried to find the right balance between efficacy and quality, but they emphasize efficacy.
When evaluating color rendering, manufacturers only look at the numbers. Whether it’s a calculation of CRI, Rf, Rg, or something else, it’s all done mathematically. There’s no interest in comparing the calculated values with empirical observations. The eight colors used to calculate CRI are a limited range that don’t include a representation of skin, as shown below.
The 99 colors used for TM-30 calculations span the color space and are not weighted toward any hue, tint, or value, as shown below.
So, there’s never been a focus on caucasian skin tone to the detriment of others because skin tone isn’t part of the evaluation.
Does that mean that all skin tones are rendered equitably? Honestly, we don’t know. On one hand, there’s no reason to think that we evaluate skin tone differently than we evaluate other surfaces. It’s reasonable to expect that a high fidelity source, for example, that give cars, apples, and kittens a good color appearance will do the same for human skin.
On the other hand, we don’t have good studies to confirm that. It may be that we hold different criteria for evaluating skin than we do for apples, resulting in the need for a separate skin tone rendering metric. Again, today we just don’t know.
In fact, the IES Color Committee is looking at this right now. We’ve started with an effort to gather as many studies as we can find – though there are very few that focus on skin rendering. The next step is to evaluate the literature to determine if additional study is needed, and what such a study (or studies) would require and evaluate. The hard part is funding the studies, and that would be the next step. Eventually, we’d have some solid science from high quality studies that would tell us if skin tone is evaluated differently than other surfaces, and if so what the calculation of a skin tone metric should include. The goal is to use the appropriate TM-30 measures (remember, there are 149 of them) to evaluate skin tone rendering, and to add a skin tone metric (maybe Rs) to TM-30, if needed.
If you’re interested in joining the task group looking at this, please contact me.
Recently, a corporate client asked me to specify only LED fixtures with a lifetime of 100,000 hours, and preferred fixtures with a life of 200,000 hours. I don’t know where they came up with these numbers, but my reply was that an L70 of 100,000 hours or more cannot be validated through standard testing procedures. Here’s why.
To begin with, LEDs themselves don’t experience catastrophic failure the way incandescent and fluorescent lamps do. The don’t stop making light, but their output declines over time. Today the generally accepted calculation of the life of an LED is called L70, which is the length of time before the light output has fallen to 70% of initial output.
The IES approved lifetime calculation method begins by collecting data using the procedure described in LM-80 (ANSI/IES LM-80 Measuring Maintenance of Light Output Characteristics of Solid-State Light Sources). Please note that LM-80 measures “LED packages, arrays, and modules” not fully fabricated fixtures, and there’s some dispute about whether or not testing bare modules is appropriate. However, it does permit module manufacturers to test once and derive a lifetime, rather than every fixture manufacturer testing every fixture with every module they want to offer, which would be incredibly burdensome and expensive.
LM-80 requires a minimum collection time of 6,000 hours (250 days) but sets no upper limit. If manufacturers want to use the data they’ve collected and project future performance they use the calculation procedure in TM-21 (ANSI/IES TM-21 Projecting Long-Term Luminous, Photon, and Radiant Flux Maintenance of LED Light Sources). Importantly, TM-21 only permits data to be projected to six times the LM-80 data collection time period. This is because of uncertainties involved with longer predictions (see PS-10-08 IES Position on LED Product Lifetime Prediction at https://www.ies.org/advocacy/position-statements/ps-10-18-ies-position-on-led-product-lifetime-prediction/). So, an L70 of 50,000 hours is based on at least 8,333 hours of LM-80 testing. That’s 347 days.
Thus, to say that an LED has an L70 100,000 hour life would require a data collection period of 16,667 hours (695 days), or 1,390 days (3.8 years of continuous testing) for a life of 200,000 hours. Today, no LED manufacturer conducts LM-80 tests for that extended period of time because the lifetime of a given LED product is too short. By the time you’ve finished a 4 year long test, the LED being tested is out of production and replaced by something new. In the future, when the LED industry has matured and we’re no longer seeing continuous improvements in efficacy, color rendering, etc., they may test for that long, but not now.
Where do these 100,000 hour and longer lifetimes come from? It seems that some manufacturers are using an internally generated prediction to get to these numbers. The thing is, we don’t know what’s involved in that prediction, which means we can’t validate it or compare it to any other prediction. We just have to take their word for it. With the LM-80/TM-21 procedure, on the other hand, we know that testing labs, regardless of who or where, are using the same procedure and their results should be consistent and repeatable. That allows us to reliably, confidently compare fixtures by any number of manufacturers.
In September at ArchLIGHT Summit, Tony Esposito and I gave a series of demonstrations on the spectral flexibility of LEDs and the possibilities they present with regard to color rendering. While there we spoke to Sam Koerbel on his LytePod podcast about the basics of the new measures introduced in Annex E, and discuss why TM-30’s multi-dimensional approach to quantifying color preference is superior to the old-standby in the industry: CRI. Our discussion is now available. Give it a listen.
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.
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.”
Yesterday an addendum to ANSI/ASHRAE/ICC/USGBC/IES Standard 189.1-2017 Standard for the Design of High-Performance Green Buildings was published. The addendum makes changes to Section 8.3.5, which covers lighting. One of the biggest changes is to add TM-30 color rendition criteria to the section on Indoor Lighting Quality. Here’s the relevant text:
18.104.22.168 Color Rendition. At least 95% of lighting power of nominally white lighting within each enclosed space shall be provided by luminaires that meet the following criteria at full light output in accordance with IES-TM-30, Annex E, P2 and F3: 1. Rf of at least 85 2. Rf,h1 of at least 85 3. Rg of at least 92 4. Rcs,h1 of at least -7% but no greater than +19%
Nominally white lighting is lighting that has chromaticity within the basic or extended nominal color correlated temperature (CCT) specifications of ANSI C78.377.
Where a lighting system is capable of changing its spectrum, it shall be capable of meeting the color rendition requirements within each nominal CCT of 2700 K, 3500 K, 4000 K, and 5000 K, as defined in ANSI C78.377, that the system is capable of delivering.
I hope that this is going to put more pressure on manufacturers to improve the color rendering of their luminaires as measured by TM-30, not CRI, and to provide TM-30 information on their cut sheets. If not, they’ll risk not being considered on projects that have TM-30 requirements.
Last Thursday Donald Trump spoke to a group of Republicans in Baltimore. One of the things he said caught my attention: “The lightbulb. People said what’s with the lightbulb? I said, here’s the story. And I looked at it, the bulb that we’re being forced to use, No. 1, to me, most importantly, the light’s no good. I always look orange. And so do you. The light is the worst.”
Now, I’m not aware of being made to look orange under LEDs, nor have I ever noticed LEDs making my friends, colleagues, or students appear orange. You can’t imagine how embarrassed I’d be if it turned out that a real estate developer and entertainer had more astute color perception than me, a lighting designer and Co-Chair of the IES Color Committee. If our only means of evaluating the color rendering of a light source, and evaluating the orange content specifically, was CRI we would have no objective way of testing his statement. CRI, technically Ra, is a single value that gives us an average of the match between the light source in question and its reference source (either a blackbody radiator or a CIE definition of daylight, depending on CCT) using only eight color samples.
Since Ra is an average value there’s no way to understand the rendering of any particular hue. I’ve talked about this here. However, one of the wonderful things about ANSI/IES TM-30 IES Method for EvaluatingLight Source Color Rendition is that we can use it to test that claim. TM-30 uses 99 color samples that are distributed across the color space and the visible spectrum.
It also breaks the color space up onto 16 Hue Bins, each one covering a specific range of the color space. In the case of orange, we want to look at Hue Bin 3. Specially, we want to look at Rcs,h3 (the subscript CS stands for Chroma Shift) which quantifies the increase or decrease in the saturation or vividness of orange compared to the reference light source.
So, let’s put the science of TM-30 to work and see if we really do know that LEDs make us look orange!
The TM-30 calculator contains a library of 300 SPDs (spectral power distributions), of which 137 are commercially available white LEDs. The CCTs range from 2776 K to 6123 K. If white light LEDs really did make us look orange we’d expect to see a large majority of them have a positive Rcs,h3, probably with an average chroma shift in excess of 10%. In fact, the 137 SPDs have Rcs,h3 that range from -8% to 1% with an average of -3.6%, a decrease (not an increase) in the saturation of orange. It’s not me, it’s him. TM-30, which uses the most modern models of human vision and a set of colors that cover the color space and visible light spectrum, proves it. What a relief!
Don’t believe me? Download TM-30 and the calculator for free from the IES web site and see for yourself.
Of course, I’m not saying LEDs are perfect light sources. Like any other product there are good ones and bad ones. However, TM-30’s measurements of fidelity and gamut (as averages) and measurements of fidelity, chroma shift, and hue shift (by hue bin) permit us to make a thorough evaluation of a light source to understand its color rendering characteristics. Using this knowledge, we can determine if a particular light source distorts colors and is appropriate for a project, or not.
I should take a moment to note another error he made when he said, “And very importantly—I don’t know if you know this—they have warnings. If it breaks, it’s considered a hazardous waste site. It’s gases inside.” Perhaps you’ve heard the acronym SSL or the phrase solid state lighting. LEDs are a version of SSL, which means that they are…well, solid. Unlike previous light producing technologies LEDs are a solid combination of materials. As such, if one were to physically break (which is unlikely since LEDs are small, are mounted to a heat sink and often covered with a lens, so you’d have to break a lot of materials simultaneously) no gas, hazardous or benign, is emitted. He’s thinking of fluorescent lamps and the small amount of mercury they contain. Even then, a broken fluorescent lamp doesn’t turn the area into a” hazardous waste site.” Here are the EPA’s instructions for cleaning up a broken fluorescent lamp.
In 2007 Congress passed the Energy Independence and Security Act (EISA) with the goal of increasing energy efficiency across the economy. Part of EISA has affected the lighting industry in the form of mandated efficacy of light sources. The initial efficacy rules targeted A-Lamps (standard household light bulbs) and set the efficacy level above that of incandescent but below that of halogen lamps. The result was a slow shift to the more energy efficient technology. Over the years the energy efficiency requirements have been expanded to more lamp shapes, always in keeping with technological ability so that we never faced a lamp shortage or loss of a lamp shape. Today, more than 50% of lamps sold are LED that exceed even the most stringent requirements.
On September 4th the administration announced that it was going to cancel a new set of requirements that would have taken effect in January 2020 that would have applied to products such as decorative medium base lamps and MR type lamps. In my opinion, this is another example of the administration cutting off its nose to spite its face. As with the threat to “investigate” automakers who agree with the State of California’s proposed energy efficiency requirements, this effort to undo energy efficiency despite the monumental consensus that we need to reign in our energy consumption isn’t going to go have any effect. No lamp manufacturer is going to reopen or build new factories to make incandescent lamps when it’s obvious that A) the next administration is going to reinstate the efficacy requirements B) the public has embraced the energy savings of LED lamps, and C) the companies know that it would be bad for their image to turn their backs on mitigating climate change.
An interesting bit of news from Samsung this week. They’ve developed an LED package especially designed to achieve an Rg value over 110, “a level that ensures lighting with outstanding color and whiteness.”
It’s important to note that increased saturation means decreased fidelity to the reference light source. This is a lighting solution that will be desirable in some applications, such as retail,and undesirable in others, such as medical facilities.