In another example of LEDs growing dominance in the lighting industry, General Electric has announced that it is “breaking up” with CFL lamps, and that it will stop manufacturing and sales of spiral retrofit lamps in the U.S. by the end of this year. According GE, CFLs and LEDs each accounted for about 15 percent of lamps sales last year. The sales of LEDs are increasing and sales of CFLs are decreasing.
A few weeks ago I gave a three-hour seminar on lighting museums and galleries to the graduate students in an art curating program at a university here in New York. Condensing everything I’d like to say into less than three hours was tough. The two big questions were what to include and what to leave out. I started with a quick overview of how to think about light and lighting before moving on to basic vocabulary and some common lighting techniques. Then, since LEDs are clearly the future, even when lighting art, I moved on to an overview of both color temperature and color rendering. I talked about reference materials such as the IES Lighting Handbook, intensity and brightness ratios, and other considerations before we moved into their gallery space to use their track light system for some demonstrations.
After the whole affair a faculty member, who sat in on most of the seminar, said he had hoped I would have spent much more time talking about how to use track lights and less time on unimportant issues like design, color temperature, and color rendering (!). I was respectful, but stunned. Focusing track lights is so complex that it requires extensive demonstrations? Understanding that with LEDs the color qualities of the light vary widely, and can only be properly selected when they are understood is unimportant information? Uhh…NO. Or, as my 20 month old niece says, “no no no no.”
Yes, five or ten years ago the default light source in museums was an incandescent or halogen lamp. The color temperature difference was minor and the color rendering of both was excellent. That’s not true today. Look at the cut sheet for any museum grade track light and you’ll see that you have a choice of several color temperatures and CRI values. If ANYONE needs to understand the qualities of light that must be selected when using LED fixtures, if anyone needs to understand the affect that color temperature and CRI have on how colors are perceived, it’s certainly people involved in displaying and lighting art. To me, that means the curators of exhibits and the lighting designers they hire.
As I’ve discussed earlier, changing the color temperature of the light changes the color appearance of objects, as shown below.
The phenomenon of color consistency means that the shift in color appearance isn’t as great as one might expect or as these photos suggest, but the shifts are real. If you’ve ever bought a black garment only to discover later that it was actually dark blue you’ve experienced this shift. A similar thing happens when we compare a high CRI light source and a low CRI light source. If your work involves color perception this is basic and critical information.
Curators can be forgiven for not knowing much about this, but if they know nothing how can they collaborate with their lighting designer to show the art as they intend? Administrators and curators of museums and galleries – educate yourselves, then hire a lighting designer!
On December 2nd the U.S. Department of Energy indued a final determination concerning energy conservation standards for high intensity discharge lamps. You can download a PDF of the document from the DOE’s web site.
Today’s New York Times has an article on several manufacturers’ new LED products that are intended to improve wakefulness, sleep, focus, and other aspects of daily life and health. The article appears on both the business and technology pages, but not on the health page, and I think that’s appropriate. Although there are testimonials by the consumers of some of these products, there’s no discussion about any peer reviewed science behind them. In fact, about two-thirds of the way through the article the author finally gets to the fact that, “Researchers are still determining how spectrum and intensity of light affect the brain.” So, the article is an uncritical look at new LED products that make health claims. We shouldn’t rely only on the claims of the manufacturers, though – remember the claims of 100,000 hour lifetimes for LED lamps?
I’m not saying that we know nothing about how light affects us, because we know quite a bit. The question is, “Do we know enough to properly and safely integrate that information into our design practice?” and there things become uncertain. So, before accepting the claims of manufacturers, or making the same claims to clients, it’s important for designers to be up to date on the current state of research and to understand the strength of the findings, as well as how (and if) those findings can be folded into a design.
There are a few web sites that I find useful for keeping up to date. The first is the Health and Vision page of the Lighting Research Center’s web site, which has links to many of their recently published research papers. The second is the Research page of USAI Lighting’s web site. This page provides links to a mix of newspaper articles and scholarly publications on a variety of topics connected to LED lighting. The third is the Research page of the IES web site. Finally, members if the IES can download copies of Leucos, and non-members can purchase copies.
LEDs continue to revolutionize the lighting industry. Most manufacturers have ended research and development for incandescent and fluorescent products. OLEDs are increasing in efficacy and prices are dropping, while new technologies (such as light emitting plasma and quantum dots) are on the horizon or already here. To preserve their client’s money, the occupant’s health and safety, and their own reputations, designers need to make sure that they don’t get swept up in the possibilities that are marketed to them before the facts are in.
A light bulb made with graphene – said by its UK developers to be the first commercially viable consumer product using the super-strong carbon – is to go on sale later this year.
Source: Graphene light bulb set for shops – BBC News
Last week I attended a webinar on the history, future, and application of OLEDs presented by Dietmar Thomas of Philips. It was an interesting and informative hour that has just been posted online. Perhaps the most surprising thing is that Philips sees commercial lighting fixtures lamped almost exclusively with LEDs and OLEDs as soon as 2020! The webinar is worth the time. Take a look.
The Department of Energy (DOE) has extended the comment period for proposed energy efficiency standards for general service lamps (GSLs) until February 23, 2015. Documents associated with this set of standards are Docket No. EERE-2013-BT-STD-0051. There is a link on that page to submit comments.
You may recall that the Energy Independence and Security Act of 2007 (EISA) set minimum efficiency standards for medium screw base (a.k.a. E26) general service lamps (a summary of requirements and exemptions is here). Those minimum standards were phased in by wattage and now cover GSLs from 40 to 100W. Decorative and other specialty lamps are excluded. A public meeting and webcast was held on January 20th to explain the new standards for consumer lamps. You can download a PDF of the presentation here. It’s a long presentation of 94 slides, so here’s a summary.
1. The DOE is considering establishing standards for the following lamp types:
2. The DOE is considering requiring the following lamps, which are currently exempted from EISA requirements, to comply with the new standards:
3. The DOE is also considering not setting standards for certain lamp types for reasons that include:
There are over three dozen identified issues that are open for comment. These standards will have a far reaching effect, so I urge you to look over the presentation and submit comments.
The Illuminating Engineering Society (IES) has published two new documents related to measuring the performance of Light Emitting Diodes (LEDs). The titles, as well as the aspects that are included and excluded, reveal the complexity of LEDs.
The basic problem is that LEDs typically do not fail the way other lamps do. Instead of a failure that results in the end of light output, LED output fades over time. The result is that at some point, although the LED is still producing light, it is no longer producing enough light for the application so we would say that it has reached the end of its useful life. LEDs have very long lives and relatively short development cycles so it is entirely possible that by the time testing of an LED is complete a newer product has already replaced it. This is compounded by the sensitivity LEDs have to temperature, voltage, and other factors that can mean lab measurements differ greatly from real world measurements. This gives rise to the need for clearly defined testing procedures that reproduce conditions found in typical installations so that designers can rely on the information from the manufacturers.
The first document is LM-84-14 IES Approved Method for Measuring Luminous Flux and Color Maintenance of LED Lamps, Light Engines, and Luminaires. (In the IES naming system LM stands for lumen maintenance, 84 is the document number, and 14 is the year it was issued or updated.) It describes the procedures to be followed in obtaining luminous flux (light output) and color maintenance measurements under standard operating conditions. However, it does not provide information on sampling, or extrapolation of the data for longer time frames.
The second document is LM-85-14 IES Approved Method for Electrical and Photometric Measurements of High Power LEDs, which describes the procedures to be followed in performing accurate measurements of light output of white and colored high-power LEDs. The procedures do not cover LED arrays or modules, AC driven LEDs, among other things.
These two documents join several others that describe the testing and measuring of LEDs. The first is LM-79-08 Approved Method: Photometric Measurements of Solid State Lighting Products, which describes the procedures for testing and reporting of: total flux (light output); color temperature; color rendering index, electrical power characteristics; efficacy (in lumens/watt). LM-79 requires testing of a complete lighting fixture. It does not apply to bare LED packages. LM-79 does not measure the distribution, only the total light output. As a result, it does not provide us with complete photometric performance of the fixture tested.
The next standard is LM-80-08 Approved Method: Measuring Lumen Maintenance of LED Light Sources, which is intended to measure only the LED package, not a complete fixture. LM-80 does not define the end of life for an LED package. It is simply method for determining the light output degradation. LM-80 outlines the testing conditions and the measurement methods that are to be used to measure, track and report the lumen maintenance of an LED package over the course of 6,000 hours. it does not provide a means of estimating life expectancy or light output beyond 6,000 hours.
TM-21-11 Projecting Long Term Lumen Maintenance of LED Light Sources picks up where LM-80 leaves off. (TM stands for Technical Memorandum) It recommends a method for projecting the lumen maintenance of LEDs using the data obtained from LM-80 testing. TM-21 is used to derive L70, which is the number of hours, or life, before the LED package is emitting 70% of the initial lumens. L70 is the number most frequently used by manufacturers as the life, or the useful life, of their LEDs.
On June 13, 2014 the U.S. Department of Energy (DOE) suspended the L-Prize PAR38 Competition. The LED PAR38 products currently on the market fall far short of reaching the rigorous L -rize targets, making it unlikely the DOE will receive a qualifying entry in a reasonable amount of time. The DOE cannot lower the efficacy target because it was set by Congress. The DOE will continue to monitor the PAR38 market for performance and price improvements, to consider reopening the competition at a later date. The graph below illustrates the market vs the L-Prize goals as of November 2013.
More information is available on the DOE web site.
Earlier this week the New York Times had an interesting, although not very informative, article about two new lamp manufacturers and their technologies. The first is Finally, a Massachusetts based company that is using an old technology, induction, to generate light. Induction lamps are very similar to fluorescent lamps except that they do not have electrodes or filaments, which are a fluorescent lamp’s most common points of failure. Instead of an electric arc passing through the gas-filled tube, induction lamps use an electromagnetic field to excite the gas. Like fluorescent lamps, mercury in the lamp produces UV light, which excites phosphors on the lamp envelope to create visible light. Induction lighting has been on the market for many years from other manufacturers. The advantages of induction include very long life, good color rendering, no flicker, and instant start and restrike. The drawback to the other induction lamps is that the equipment producing the electromagnetic field is bulky. The Finally lamp manufacturer has found a way to shrink the equipment to the size of the ballast in a typical retrofit CFL lamp. The only drawback is that it cannot dim with conventional wallbox dimmers.
The second lamp is the Vu1. It too uses an old technology in a new way. The Vu1 is essentially a cathode ray tube, just like old televisions and computer monitors. It fires a stream of electrons at phosphors embedded in a glass plate, which in turn produce light. It does not contain mercury, is instant on, has excellent color rendering, and is dimmable. It is currently available as an R30 replacement lamp.
Since both of these lamps are designed for the retrofit market, they aren’t likely to be specified by lighting designers. Nonetheless, I’m looking forward to seeing them in operation, and I’m excited to see some alternatives to LEDs. It will be interesting to see where these two technologies go in the next few years.