LEDs: Throwing Some Light on the Hype

Let's start this off with a quick clarification. When I say "LED light", I'm not talking about the nifty, little blinky things that are frequently part of the ingredients list in Make projects. I'm talking about the Big Show: An LED light that can replace the incandescent bulbs and/or CFLs you have lighting up your home right now. To do it right, you don't just need a single LED that works, you need an array of them...and you need them to produce enough light, and the right color of light, reliably enough that people can buy an LED bulb and know what they're getting into.That ain't easy. But it is getting easier.


LED lighting really is more than a toy. This is the library of the new Wit Hotel in Chicago. It's not lit entirely by LED, but lighting designers Lightswitch Architectural did use the technology in the coves around the ceiling and walls. Unfortunately, getting this look at home isn't as simple as it's often made out to be.

Trouble is, they're being oversold, like whoa. For about two-and-a-half years, I've been reporting on LED lighting for a trade magazine called Architectural SSL*. During that time, I've watched mainstream press and enviro blogs tout LEDs as the green energy miracle light. Often, with a level of enthusiasm seldom seen outside rooms full of puppies. Don't get me wrong. LEDs are pretty cool. There are places where they're useful now, and places they probably will be soon. But if you're just hearing about the awesome, you aren't getting the full story. And, as more LED products start showing up on store shelves, that really starts to matter.

Join me, won't you, as we put on our Sober Assessment Goggles and take a peek at the current state of light bulb of the tomorrow...

*The glamorous life of a freelance writer, everybody. That said, if you are thinking about freelance, I recommend convincing a trade magazine or two to love you. The work is steady, the pay is decent and the people are good. And that is a better situation than you'll get from a lot of things you could do to pay the bills. /unsolicitedwriteradvice

1. There Are Good LED Lights Out There; But You Probably Can't Afford Them
A Twitter friend lamented the other day that LED lighting technology just isn't getting any better. And that's wrong. Right now, if you were a city manager, the owner of a fine hotel (like the Wit) or somebody with enough cash to hire a lighting designer to pick out the fixtures in your living room, you could go drop some money on LED lights that would work great, look beautiful and (depending on your project) give you some big savings on energy use. The obvious problem here is that, with a few exceptions, you are likely none of those things.

No, what you see is the stuff for sale at Home Depot. And that, my friends, is usually not worth your time or money. Not yet, anyway. Buy 'em if you want, but prepare for disappointment...Christmas tree lights that say "white" and turn out to be blue...$20 lightbulbs that conk out after two weeks. That's a lot of what's out there. Case in point: A couple weeks ago, I was at an LED conference and one of the speakers told a story about buying 10 screw-in LED lightbulbs from his local Costco, just to see what they'd do. The box claimed they'd last 30,000 hours. Within two weeks, four were dark, and one had changed colors and started blinking. Less than two months later, all the lights had dimmed out enough to be useless. I've heard that same, basic story about 50,000 times now. Sure, there may well be good, affordable products out there. But you have no way of telling the difference, which brings me to....

2. Trust No One
See, the LED industry is kind of in this awkward teenage phase right now, where it's doing the business equivalent of tagging public buildings and sneaking cigarettes out behind the barn. There's a lot of misrepresentation and a lot of flat-out lies, and just because a box says something that doesn't mean you can believe it (more so than boxes of other things). In fact, up until last year, there weren't really any useful standards to compare LED lights. Anybody could make any claim they wanted to and even the professionals had nothing to judge it by. That's changing, but for now, assume you're dealing with the early 20th-century patent medicine industry.

Again, yes, there are good products and there are honest companies. But finding them takes a LOT of research. Last year, at that same LED conference, I watched a discussion panel devolve into (literally) tears and yelling over this very topic. The phrase, "Pull up your big boy pants," was shouted. This isn't yet a place where average consumers can just walk in and grab something off the shelf.

The DOE is trying to fix that, though. One way they're fighting back is with CALiPER, basically a secret-shopper program with a lab experiment twist. Researchers from the Pacific Northwest National Laboratory (and other labs) purchase LED bulbs and fixtures anonymously (often via third-parties) and run them through an extensive testing process to see whether they live up to the claims on the box. The majority still don't, though it's getting better. More than 175 products have been tested since 2006. But, while CALiPER is improving the overall situation, it won't help you a lot. The reports are fairly technical--they're written for lighting designers and engineers--and the DOE doesn't name names. CALiPER can tell you whether, in general, you can seriously consider a certain type of LED bulb. But it can't tell you what specific products are bunk.

3. Keep a Close Eye On that "Energy Efficiency" Thing
The biggest selling point--at least for average consumers--is that LEDs are more energy efficient than any other kind of lighting. They'll slash your bills and save the planet! Rejoice!

You can probably guess where this is going. The fact is, LEDs are pretty damn efficient. Much, much more so than the old, incandescent Edison bulbs. But they aren't always a greener choice compared to fluorescent lamps. The thing to look at is lumens per watt, a fancy term that basically just refers to how much light you get out vs. how much energy you put in. The more lumens per watt, the better the energy efficiency. The kind of fluorescent lamps used in offices--the long, narrow ones that are called T-5 or T-8s in Technicalland--regularly get more than 100 lumens per watt. An LED T-8 lamp tested by CALiPER last year got 42.*

Plus, the lumens per watt rating of the LED itself doesn't necessarily mean that a lamp made with an array of LEDs will get the same rating...or that a fixture made with a couple LED lamps will even get close. You lose efficiency each time you add other parts to the system. And many times, when you hear about super-efficient LEDs, you're hearing about just the single LED, not about its efficiency in a complicated system.

If you do happen to be in a position where you can buy LEDs, and you care about the environment, this is something you need to be really critical about. A good green PR campaign isn't the same as actually green numbers.

Again, I want to stress that LEDs don't suck. And where they do suck, they're getting better. But I don't want you to get burned by hype. And right now the amount of hype surrounding these things would make Flava Flav blush.

*Yes, fluorescent lamps contain mercury. But so does the pollution from coal-fired power plants. This is part of what makes the green-ness of LEDs so complicated right now. If you get your energy clean, it might well be more green to buy an LED over a fluorescent, even if it uses more energy to produce the same amount of light. But if your energy comes from coal, that could change the equation, especially when you consider the fact that a lot of cities have good fluorescent recycling programs.

Thumbnail photo: Goins


    1. Completely different thing. I know nothing about the LED TV market, but from what I’ve heard it’s not having these sort of problems.

  1. Very interesting article! Certainly not the usual boingboing fare, but I like it.

    Can you comment on specific brands? What do you think of the architectural lighting developed by Cree? They claim to be paying a lot of attention to things like how the heat gets rejected from the fixture and so forth, and they also claim to be having a lot of success in installations like airports, exhibit halls, and auditoriums.

    If you can comment on that or any other brand, please do!

  2. Thank god someone has brought some reason and logic into this area. I posted on a different thread about this exact thing.

    And 42 lumen sounds about right for the tech we have now. Luxeon and Cree both make some fairly high powered leds that are pushing 200 lumen from a single unit. However you’ll still be burning 5-6 watts to do that. (You are starting to see these get popular in the flashlight market as well.) And there’s another issue, heat.

    Anyone familar with processor cooling in a pc should understand the issue with a die shrink and cooling. If that led is tiny, and it has to dump ~5 watt of heat, then it’s gonna get hot, and if not cooled well, really hot. I retro fitted an old 6V lantern flashlight to a Luxeon K2 led, and was suprised by how much heatsinking the led assembly needed in order to maintain brightness without exceeding it’s temperature limits.

    I think the high power market will drive along the efficiency of the smaller units, and if things like spray/paintable semiconductors work out then led’s would be an easy choice. Until then, they have their market. Replacing 100W (equivalent) CFL’s is just not one of them.

    1. Bcsizemo: I didn’t even get into all the manufacturers claiming that LED lights “produce no heat”. But that’s definitely one of the big ol’ marketing falsehoods going around. Sure, you can touch them and not burn yourself, but that doesn’t mean there’s not heat that needs a place to go.

      jwb: I’m not going to get too into back-patting because my information on which companies are the good ones comes very second-hand. But it is my understanding that Cree are part of the good guys on this–producing quality products and being reliably honest about them.

  3. I have a couple of 240V 3W GU10 LED bulbs. A lot more expensive than the 20W halogens they are replacing, and it’s too early to tell how long they last, but they are looking fairly plausible. (One is a bit bluer (or less yellow) than the halogens, the other is a pretty good match.)

    Of course many applications use lights more powerful than 20W in the first place.

  4. The matter of fact where LED gains over traditional lamps is the amount of heat generated vs luminiscence.
    While considering the above, If you have 5 bulbs vs 10 LEDs to give you same lumination, you would still see a positive in LED for heat generation.
    Yes, we might not be there right now, but we still have much faliures to cover before saying TADA..

  5. The manufacturers aren’t exactly lying when they say LEDs produce no heat compared to other technologies. The problem is that the miniscule amounts of heat are generated over a very small area, giving a very large heat flux. Large heat flux is the bane of heat exchanger engineers. Especially in tiny environments.

    There aren’t that many ways to dissipate heat. A chunk of metal can increase dissipation area, but alas you are still ultimately screwed if the heat sink is in an enclosure. Forced air is messy and complicated, solid state cooling just moves the problem a few cm away, water and VCC are just not an option for commodity products like light bulbs unless someone can produce MEMs size cooling devices that are incredibly cheap <$!1.00US Heat dissipation is the limiting factor in all transistor based devices.

  6. I’m interested in LED lighting– mainly because I’ve got this really elegant ceiling fixture in my living room that was designed by an idiot (or, more likely, a team of idiots). Replacing the bulb in the fixture means, basically, disassembling it, while on a ladder, juggling various pieces of glass, trying to remember which screws unscrew normally and which ones unscrew backwards. Replacing the bulb with an LED that wouldn’t have to be replaced would be… really nice.

    1. MattF: The problem there is that the LED light itself rejects most of the heat from the back of the fixture, which is the opposite of how an incandescent bulb behaves. So normally you need an LED light and fixture which are designed to work together to cool the light effectively and not set your ceiling on fire.

        1. MattF: even so, check out the Cree LR6 or LR4 (depending on the size of your fixtured) for a quality LED bulb that fits in a regular light bulb socket.

  7. It’s a great and necessary article, but without some positive examples, it’s left me with a feeling of coitus interruptus.

    OK, there’s hype. But what are the real world (architectural etc) applications where good LEDs are possible?

    For example, a friend manages a medium retail supermarket, using a lot of MR16 halogen spots for product lighting. I’m telling him, (based on theory) LED substitutes would save him a lot.
    He needs long life (at least 2 years plus), good light (not flat white but with a little bit of warmth), and a purchase figure that I can rationalise into calculating a saving for him, (say something like 4x the cost of a standard MR16 halogen but with 6x the life & 1/4 the running cost).

    Right now, all we’ve got are product manufacturers claims. And that’s too risky to take an (expensive) punt on.

  8. Color Rendering Index is also important. I think LEDs have a better chance of getting this perfect than CFL, but at this point they both suck. When the CRI is low, people keep adding more light in order to see through the muddy and unsatisfying illumination. This of course eliminates any gains one may get with better efficiency.

    When incandescent bulbs become banned, I will be buying a hundred or so and hoarding them for the rest of my life. I don’t accept anything less than a CRI of 99.

    1. Incandescents won’t be banned. The law doesn’t target them, it targets inefficiency. Manufacturers are developing incandescents that meet the requirements.

  9. Best article I’ve seen in quite a while here at Boing Boing, but the question remains: where can we find the good ones? And that explains a lot about the LED flashlights that last less than the batteries themselves…

    1. RE: Where can we find good ones?

      That’s an interesting question. My suggestion is to look to the Internet, specialized lighting stores, or talk to lighting designers.

      As several people have said, companies like Cree seem to be doing a good job (And there are others that do as well! I just haven’t done enough research to be comfortable giving you a list.).

      Good stuff is out there–especially for exterior/parking/street lighting–but it won’t be cheap and it’s probably not something you can find at any of the places you usually shop.

      1. Actually, on the exterior lighting front, I am comfortable name-dropping Beta/Ruud Lighting as a good manufacturer.

        They’re doing some awesome things with parking garages and street lighting, using LED’s ability switch on and off without a warm-up time.

        Think: Parking garages that are set to motion sensors. You save a ton of energy and money when the lights don’t have to be one full-bore 24/7.

        Also: Street lights that can be programmed to blink in front of a specific house so that ambulance crews can find it faster at night.

        Very, very neat. Ann Arbor, Michigan is in the process of going LED for their street and public lighting.

  10. The problem I have had with both LED’s and CF’s is the Color Rendition Index (CRI). In order to boost the claims on lumens/watt they push the green spectrum. LED’s tend to be more on the visibly blue side because of the superbrights, but the CF’s makes yellows look green when the lights are on, and skin tones are just horrendous. I have used some t-8’s that have a good CRI, but even the CF’s that claim a high CRI don’t look like they have anywhere near what they are claiming, and independant testing seems to back that opinion up. I am wondering when the LED’s might have honest CRI’s in the 90’s?

    1. The CREE LR6 has a CRI of 92. It is one of the few that is ready for prime time. They are not cheap (retail around $130, that includes the integrated trim), but I wouldn’t put anything else in my home (except in wet-rated locations, where now CREE doesn’t have a product, and I used a very good, but not as good, HALO LED). The light output is BETTER than a 65 watt incandescent, great CRI, and only 12 watts. See discussion at http://greenhomesamerica.wordpress.com/2009/11/06/halo-led-lighting/

  11. Excellent article. I’ve been trying to figure out LED lighting for a long time and you’re right the claims can be pretty crazy. Right now the extent of my lighting is CREE flashlights which are truly amazing. When you see the light they throw with a single AAA battery, and how long they last on that battery, it makes you wonder why we don’t have that level of awesomeness for indoor fixtures.

    Your article has excellent background to help understand that. I can’t tell you how much money I’ve spent on LED Christmas lights. It seems, at best you get 2 years out of them. Totally wasteful.

    I want to know more about what would cause tears at an LED panel.

  12. The other big issue with fluorescent light bulbs though is that they use mercury. Even ignoring the environmental impact of that, we break bulbs often enough that I have stopped using compact fluorescent bulbs entirely, and only use the tubes in covered light fixtures.

    I also wonder what percentage of CFL users use proper disposal methods for the bulbs.

  13. Spot on! I was at Home D’ the other looking at LEDs. A nightlight-type bulb’s packaging touted “90% energy savings” (wowee, save the planet, it’s a freaking nightlight bulb). Nowhere on the package, nor on the part of the bulb that was visible through the clamshell pack, did anything mention the actual wattage of the bulb. I wanted to know does it draw 1/2 watt? less? For $4.97 I wasn’t curious enough to find out. As for the blue “white” Christmas lights, why can’t they filter the light to make it a warmer white? They do a great job, really pure colors, on the colored lights.

  14. mmm no, the Mercury in cfls is not a “big issue”. In fact, it is not an issue at all. In March 2007 NEMA announced a voluntary commitment to cap the amount of mercury in their CFL products offered for sale in the U.S. at 5 mg for CFLs that use less than 25 watts of electricity and at 6 mg for CFLs that use from 25 to 40 watts. Since then, Hg levels have fallen even further. Currently the average Hg content of a cfl bulb sold in the US is 2-3mg. That is practically insignificant when you consider that the EPA estimates <10% of that Hg is actually released as vapor when a cfl is broken. The levels are getting so low I would argue that it's not even clear that disposal as hazardous waste for small bulbs is even warranted anymore.

  15. @Thalia The amount of mercury in CFLs is miniscule. Almost an order of magnitude less than found in your average mercury baby thermometer (anyone remember those?). And it is decreasing all the time.

    Unless you are breaking a bulb a day into a totally closed room, the risk of mercury exposure from CFLs just doesn’t exist. You are likely going to be exposed to more mercury from eating fish or other environmental sources.

    Cleanup isn’t that big of a deal; ventilate the area extremely well and use a wet cloth or paper towel to mop up the itty bits. Then vacuum with a HEPA filter vacuum (of which, most people should have a HEPA vacuum anyway just because the damned things do such a wonderful job of cleaning up mold spores and other nasty tiny things).

  16. Thanks for the interesting article – here’s a ‘trade magazine’ for you – quite technical, but usually the stories in it are about two to three years (or more) ahead of commercial products. Also, because it is really for industry insiders, not consumers, it goes into considerable detail about technical problems, new approaches, and their limitations. It is Photonics Spectra and has all kinds of cool stuff about ultrafast lasers, LEDs, and optical fibres.

    Personally I am always skeptical of claims made for new products (especially of the ‘It will save the earth!’ variety), It was not that long ago (I think in the seventies / eighties) that all kinds of dire health warnings were being put out about fluorescent bulbs because of their perceptible flicker (don’t believe me? track your eye really fast past a fluorescent, especially in a dark room and you will see the multiple images) which was supposed to be bad for your eyes, or mental health, or cause headaches or something. Incandescent lights don’t flicker in the same way, as the filament stays hot as the AC current reverses.

    There is no doubt that the colour spectrum of fluorescents only badly approximates sunlight. It leans pretty heavily towards green. The LED’s I’ve seen have an even less appealing glare.

    We are all to ready to trade supposed energy / ecology benefits for unpleasant lighting.

    Something rarely mentioned in these discussions is the ‘life cycle cost’ of the products. There is a considerable investment in energy, petrochemicals, glass, and exotic materials attached to LED manufacture. There is also the cost of safely retiring the used product (and by this I do not mean the landfill). How do these costs compare between conventional incandescent, all the versions of fluorescent, and LED’s? I don’t know, but I’d like to, before I buy the new stuff.

    In any event, I probably won’t. I live in a 140 year old Victorian house, and incandescent lights fit it better than anything else. I’ll just have to continue to turn off lights when I don’t need them.

  17. I get to see new LED fixtures on a weekly basis. As was stated in the blog, many of these things work great for the first week or so with promises of 50,000 hours or more. The biggest problem that i see is with heat transfer. Some of these fixtures/lamps have elaborate heat sinks which are extremely important for the LED to operate properly. What happens when these heat sinks get coated in dust. They lose their effectiveness, and cause premature failure.

    Another problem is quality control. Many of the lamps on the market are being mass produced in Asia by no-name companies. Although the LED’s they are using may be of good quality, the build quality of the lamp assembly is horrid.

    LED’s IMO work great for cove lighting and accent lighting. However, I still get excited with every new product that i review.

  18. I’ve been slowly rolling in LED lights into my kitchen track lights for the last two years. Very happy with them. No problems 9other than on fixture flickers — it the fixture, not the LED) It’s a little whiter than my wife likes, but I really like them. At $45 a pop, they’re not cheap. I think they’re 100W equivalents, running 7W, Par30 types. And they aren’t nearly as hot as the CFLs get.

  19. We recently renovated our kitchen and used Cree LR6’s for general lighting. They’re the real deal– 900 lumens at 12 watts, 92 CRI, rated at 50,000 hours and with a 3 year warranty.

    Most of the fixture is heat sink. Even at 100 lumens/watt, only about 15% of the electricity is being converted to light. The rest has to dissipate as heat. That’s still much less than a given lumen output incandescent, but it’s a notable amount of heat, and as others have said, it’s from a small source, so harder to dissipate effectively.

    Any high efficiency lighting–LED, CFL, etc–are still very much “buyer beware”. There’s a lot of crap on the market.

  20. I patiently and optimistically await this technology, for one reason that’s kind of personal:

    The writing is on the wall, and eventually incandescent lights will be declared evil and illegal. Florescent lights–even the good, expensive ones–make me feel depressed and uneasy (I seem to be pretty sensitive to lighting conditions in general, and the seasons and weather affect my mood greatly).

    That leave me with… patiently and optimistically waiting for LEDs… Seriously, I would move to oil lamps before bringing flourescents into my home.

  21. I’ve bought a few LED bulbs, but their use is limited to hallway and foyer lights because the green-yellow color is too unpleasant for actual living spaces. I also use them on a couple outdoor fixtures that are meant to illuminate the front of the house (which I know is light pollution, but that’s what the neighborhood requires).

    But it seems we’re a long way off from having LEDs that are akin to the nice purple-red glass incandescent bulbs that I love the most — the kind that is sometimes sold at WholeFoods that create a nice rosy kind of hue.

  22. More articles like this, please, BoingBoing!

    Part of the misrepresentation (same misrepresentation is present with hard drives) is the mean time before failure (“MTBF/MTTF”). This is an indication of how many hours of its working life an otherwise working, non-worn-out device will go before experiencing a random failure.

    It is NOT the expected lifetime of the device!

    To find lifetime: take 10,000 known-working bulbs. Run them until they all fail. Take the mean value, it might be 1,000. And very few, maybe 10, had failed in the first 100 hours.

    To find MTBF: take 10,000 known-working bulbs. Run them for 100 hours. 10 fail. Your average MTBF is therefore 10000 * 100 / 10 = 100,000 hours.

    MTBF is often quoted on advertising because it is such a misunderstood statistic. It does NOT tell you how long your device will last. It just tells you what your odds of a failure are in the first few hours of use.

    Worse, I’m betting that the MTBF quoted is often that for a single diode, on the assumption “well, the MTBF for one is 100k hours, so they’ll all have that same MTBF, right?”

    But an array of diodes will have a much lower MTBF. Simplistically, if the odds of 1 diode failing is 1/10000 per hour, the odds of one of the 100 diodes failing is… 100/10000 per hour, or an MTBF of only 100 hours.

    Except it’s more complicated than that, because of the bathtub effect. But either way, lifetime<

    1. Simplistically, if the odds of 1 diode failing is 1/10000 per hour, the odds of one of the 100 diodes failing is… 100/10000 per hour, or an MTBF of only 100 hours.

      I just have to nitpick here : the 100 * 1/10000 is only an approximation since the probabilities are independent. It’s really 1 – (9999/10000)^100. Which is pretty close to 1/100.

  23. Fascinating article! One of my friends is involved in work on LED light bulb technology. He adores the ones he has, but they are a tad bit expensive for common household use (one LED flood light bulb runs about $25+). He is also guaranteed, by virtue of being involved in the mfg. chain, of getting quality products. I am buying a couple of the Hong Kong special screw-in LEDs to replace the incandescents in a low-use application (a spare bedroom presently used for storage). For $3.50 per bulb, I reckon I can conduct my own little test to see if it performs as advertised.

    Last year I bought a couple of LED strip lights to use as lighting under my kitchen cabinets. I thought they would be good as night lights and supplemental low-heat, low-power task lighting. A year later, they are out; one had half the strip die in 9 months, and neither threw sufficient light to justify the expense.

  24. “why can’t they filter the light to make it a warmer white?”

    Because you can’t filter colors it doesn’t produce. White Led’s (and fluorescent tubes btw) produce white light by starting with ultraviolet and then have the UV cause some material to fluoresce. In the case of FL tubes, it’s the white powder inside the tube, for Leds it’s cast into the plastic around the actual chip. You have to use a blend of fluorescing materials to get a good spectrum of light, but this is expensive and will change as the bulb ages.

  25. @ Donal:

    Have your friend consider ceramic metal halide. There are new MR-16 sized CMH lamps that are perfect for retail environments. Long life, great color and high efficacy (lumens per watt). The only issue is the 5-7 minute warmup time to stabilize the salts in the morning but they are what I recommend for retail establishments. Everything the LED promises but cannot yet deliver.

    The main issue is going to be purchasing new fixtures, there are no retrofit kits due to the need for a ballast for the lamp.

    Maggie, great article, nice to see rationality and facts brought into the hype of LEDs. They’re just not there yet everyone!

  26. walnutcrunch: The reason LED flashlights have such amazing battery life isn’t because the bulb itself is all that more efficient than a halogen bulb. Rather, it has to do with the electrical characteristics of LEDs versus incandescent bulbs – as the battery drains and its voltage drops, an incandescent filament gets cooler. As it cools, its resistance decreases, allowing more current to flow, and thus draining the battery even faster.

    An LED doesn’t have this problem, and so it can produce useful amounts of light for longer.

  27. Good, if rather frustrating, article. If the industry is immature and needs quality control and standards, why not do your bit and name some good brands and producers so that newbies don’t get ripped off? I’ll nominate bulbs based on Sharp’s Zenigata LED, which I hope might help somebody.

  28. I’ve worked with Luxeon, Cree & Ledengin diodes with good results. There are several other reputable sources out there, too. Osram comes to mind.

    I think the future isn’t in LED replacing conventional light bulbs, mostly due to the thermal issues, but in rethinking how we illuminate our environment from the ground up. Since quality LEDs in well designed fixtures should last a lifetime, replacement will become less of an issue, and lighting will be built in to our buildings. And since it’s easier to move the heat away from ten separate 5 watt LEDs than it is a 50 watt LED or a 50 watt cluster, room lighting will be distributed throughout the space, with smaller, specific task lights to augment needs for reading, close work and such.

    That said, my current fan cooled 40 watt LED flashlight project is providing plenty of design fun.

    And as has been mentioned, LEDs aren’t the only path to the future of lighting. Here are a couple of interesting links (I have no relationship with these companies).


  29. @Gilgongo,

    I don’t name drop here because no manufacturer puts out a completely solid line yet. There are incredible Cree LEDs, but there are awful Cree LEDs. There are very useful Color Kinetics fixtures and not as useful Color Kinetics fixtures. Much of it comes down to how the fixture deals with heat and proper binning for consistent color. Additionally, fixture manufacturers may start using one brand, establish a reputation and then change to another brand which may not have the same quality control in the past.

    And then there’s just personal preference and application. There are people I’ve dealt with in the past that cannot stand one particular color temperature that I prefer. There are those who see a flicker where I don’t. And there are those who are just not willing to spend the money. It all comes down to what the end user wants and I’m not willing to make blanket statements about LEDs when it’s all going to change in a year or five when Philips or GE purchase another round of companies and make additional sweeping changes to the supply side of the industry.

    As a side note, I see a lot of talk about how long LEDs last but nobody seems to mention the transformer/drivers for these fixtures typically having a 2-3 year guarantee. You might not have to replace the LEDs, but you’re going to have to get to and maintain the stuff that provides them with power.

  30. I see the large scale led lighting market facing the same issue that the solar cell market does for large scale power generation: silicon

    We are still basing the creation of leds and solar cells off of a standard silicon wafer build up design. And frankly that works great, but the cost is fairly high. For something like Nasa, a power plant, high end designer pieces all that is fine. But for cheap mass production, you need a cheap/easy was to produce them.

    Considering leds are diodes (all be it highly doped), and solar cells are based on a diode like structure, solving one side would probably lead to solving it for both.

    And for the technical part:

    Leds are current driven devices, the input voltage is somewhat irrelevant (as it is tied to current anyway). So if your K2 Luxeon bulb has a forward voltage drop of 4 volts and is optimally driven at 1 amp, then you have a 4 watt power dissipation on the led. P = I x V Since leds are diodes you will always have a voltage drop, and thus implies power consumption/dissipation.

    And the flickering thing: I have nystagmus. Which has imparted me with the lovely ability to see flickering into the 100+hz range. Those led Christmas lights drive me insane. Led tail lights on most cars (and BMW especially), flicker when on (the brake makes them go full bright, so I assume they are doing some form of PWM with no filtering.) Leds can work fine on standard AC if a filter capacitor is used, or a bridge rectifier, or a dedicated SMPS chip. I imagine this is an area that varies widely between vendors of Led lighting.

  31. I also would like to see more articles like this. i was also really grateful to the commenters who discuss CRI. As a photographer who hates light from almost every CFL with a passion and isn’t too wild about halogens, I’m hoping that LEDs will end up being a practical source of good-quality light. I really don’t want to have to fill my attic with a life’s supply of incandescent light bulbs, but if there isn’t a technological fix, it’s that, kerosene lamps, or maybe literal rose-colored glasses. Green light is really depressing.

  32. Great article. Informative, detailed, measured, well-written and entertaining, all at the same time.

    More, please.

  33. For most commercial applications (and recessed cans in the home) LEDs are ready to go. We just installed LED cans in our new photo/video studio in place of CFLs. Slightly more expensive, last way longer (so cost over the lifetime is less), you can dim them, they use very little energy and output the same amount of light, and they won’t shower you with mercury if someone happens to break one … what’s not to love. They fit into the same housing as a typical can and use three LEDs behind a diffuser … we went with Cree but Halo makes them as well. And … they more than meet California’s Title 24.

  34. The first thing people need to get straight is the difference between the LEDs themselves and the finished bulb product. A huge number of companies are using brand name LEDs like Cree, Nichia, Osram etc to make bulbs. Only a small % of those bulbs are worth buying, as many have poor heatsinking, crappy driver circuits etc, and don’t last long./ Is a waste of excellent high grade LEDs of course, but it is common.

    Now, by far the most efficient LEDs on the planet are made by Cree and Nichia, both companies have LEDs that are in the 130 lumens per watt category. For cree it is the new XP-G range, but even their previous offerings like the XP-E and their mainstay, the XR-E, ran into bins of over 100 lumens per watt. When these are coupled with a well designed fitting and driver, then you end up with fittings close to 100 L/W overall efficacy.

    The nicest downlight fitting I’ve seen so far is the cree LR6 and LLF units, very impressive devices with CRIs over 90, but they are expensive. But, there are a lot of other units out there using cree LEDs that are pretty good, such as those below.






  35. I just installed some Sylvania LED lights to try them out and I love them. They’re perfect in the places where CF lights are not, namely where you would use flood lighting and track lighting.

    I plan to replace my track lighting with LED lights simply because they look *better* than the traditional incandescent flood lights I’m using now (and way, way better than CF lights). That they use a fraction of the power is merely a plus.

    They are a bit too expense right now, but the price will inevitably come down.

  36. A couple of comments on comments — I second jimkirk’s point on redesigning lighting overall, not just the bulbs. I’ve used LEDs in various ways (CREE XRE and Luxeon Star III, with drives from ledsupply.com), and had pretty good luck, but I’ve always had good heat-sinking (either individual pucks on aluminum pads, screwed to the bottom of kitchen cabinets, or glued to a piece of aluminum on the air stream at the front of a bicycle). Figuring out how to get the heat out of a single screw-in LED fixture emitting the light of a 100 watt incandescent, would be a pain. The heat-sinking is incredibly important; all the LEDs are less efficient at high temperature, and they’re also less efficient at high power, even if you hold temperature constant.

    And the bit with nystagmus and the PWM, someone’s just got to do a better job. You can chop LEDs plenty fast, faster than the 120Hz that we can easily see. For example, a “BuckPuck” driver supports a pulse rate of up to 10kHz, and the driver (slower than the LED) has a rise/fall time of 25uS or less. It would be a bit of design work, but in an array, you also ought to be able to chop sets of LEDs at different phases, which I think would fool your wiggling eye. Of course, the whole point of cheap snake oil, is to not bother with the design work.

    If CRI is important, avoid the “brightest” LEDs, which will inevitably be “cool white”, and emit the gentle light of a welding arc. I’m using CREE XRE “Neutral White” in my kitchen, and they’re pretty good, though not perfect (there is a slight green, not much — there’s a picture on my blog, search for “undercabinet”). I bought more, later, and the second batch seemed noticeably greener. If I had it do over again, I would mix it up to include some warms and a few cools, as insurance against an overly green batch of “neutral” LEDs.

  37. The article is correct for the most part. If you want to buy ready made high brightness LEDs they are prohibitively expensive. However if you are willing to do the searching, research and do some building yourself then it can be reasonable and even fun. I am working with some 5-10 watt (400-600 lumen) LEDs that are pretty reasonable. Some I get from eBay and others are available at the major distributors. Finding high current drivers are harder but they are out there also. LuxDrive has some great drivers at 1A or less but will build one higher if you ask. ADDtek Corp’s drivers are showing some promise as an easy to design circuit.

    It’s going to take awhile before high brightness LEDs are at a reasonable price but until then if you are willing to do the work you can build your own and have fun at the same time.


  38. As a lighting pro I can only confirm what the writer of this article says. We are building SSL systems now for over ten years and they all are still operational. The substitution concept is soooo wrong. And is going to compromise the LED as a reliable light source.

  39. A few random points:
    Consider that “waste heat” is not always wasted. In the cooler seasons and climates, that heat supplements the heating system. On the other hand, in the summer cooling season, an additional 30% to 40% energy is needed to remove the waste heat.
    Many people object to the daylight color balance of CFL’s and LEDs. There are CFL’s that have a color balance similar to incandescent: they are labeled “soft white”.
    Florescent bulbs are capable of very good CRI, if you want to pay for them. They are used in the publishing industry in “color booths” to judge printed versus original color. They usually change them once a year, and the old bulbs may be discarded.

    1. Actually, the waste heat from light is wasted, because heating a home with electricity is inefficient. A good fossil-fuel burning power plant might be 40% efficient in converting fuel to electricity. Transmission losses waste another 5-10% of the electricity. Burning natural gas, instead, converts at least 80% of the energy to usable heat.

      So, you’d be better off switching to more efficient bulbs, and letting the heater do the work it’s designed to do.

  40. LEDs are much longer lived than any other lighting technology. The problem is that they need a current regulated DC power supply to drive them. Mass produced (cheap) power supplies tend to be rather unreliable. CFLs also have a built in power supply. I have fixed several CFLs which failed prematurely by cracking them open and swapping the power supply from another CFL of the same type which had a bad bulb. Others were fixed by replacing bad capacitors or just soldering bad connections. I suspect that in many bad LED bulbs the LEDs are fine and the power supply is bad.

  41. Thank you for this article and for everyone’s comments also. I agree with all who asked for more coverage on this subject, and like many I am also waiting for good quality LED lighting products to become the norm rather than the exception, to improve their light output, and to come down in price.

    I recently picked up a Pharox 60-watt-equivalent dimmable LED bulb. These are made by Lemnis, a spinoff of Philips. It’s the first LED replacement for an incandescent bulb I’ve seen that produces “normal”-looking light. Very pricey, unfortunately, but I sure like it.

    I think this product may be pretty close to the bulb Philips entered in the recent DOE “L prize” competition. I also have a few of Lemnis’s predecessor 40-watt equivalent bulbs and like those as well.

    The color of the Pharox bulbs, metrics aside, is warm and well-designed. When lit the bulb itself looks yellower than most incandescents, but the quality of the light it throws is pretty reasonable. A review can be found here:

    The color problems people describe about LED light reminds me of the sound qualities many people complained of when CD’s first appeared back in the early ’80’s. Too digital. I expect those things will improve as the technology develops.

    For now I’m happy to see others interested in advancing this technology. I’ll take a look at the Cree products and hopefully learn a bit more from what you’ve all posted.

    (More about the “L Prize” at http://www.lightingprize.org/).

  42. A second comment, this time on color rendering. It is useful to look at the emission curves for the various lights, and it is also useful to get a diffraction grating and check for yourself (there’s one in the Klutz exploratorium book). According to a physicist friend, and verified on every fluorescent light I have checked, ionized-gas fluorescent bulbs emit light at a small number of discrete frequencies, and sometimes, this looks wonky. (says the physicist, they used wavelength-multiplying phosphors). Through a diffraction grating, you will see distinct copies of the light, in different colors, at different displacements from the actual light.

    LEDs are different; the basic mechanism produces a range of frequencies grouped around a center frequency, and, if you use those same phosphors to convert blue/violet into white, you get a multiplied range. My understanding, from reading wikipedia (and my son had a bike light that did this) that are some that just do “blue+yellow”, and those are crap. Good ones don’t do that. Unfortunately, your only hope for getting a “good” LED is to buy a from a reputable supplier, or get your hands on the data sheet for the LED you are buying (or both). Even with good ones, there seems to be a blue spike at the underlying LED color.

    Examples below:




    1. For those of us who don’t have diffraction gratings laying around, a CD or DVD makes an excellent diffraction grating. Simply look at the light reflected in the colored reflections of the disk.

  43. A while back looking at the current state of LEDs, one area of the net that was fairly knowledgeable was marijuana growing discussions. Those people are really concerned with spectrum and power issues maybe even more than lighting engineers.

  44. @ mccrum

    OK fair enough – it is a jungle out there.

    As to your point about power supplies needing to be replaced every few years, I’m using AC mains-powered GU10 LEDs for that reason. I’m not sure what the advantages of 12V circuits are for this though. Anyone know?

  45. Nice article, thanks for posting. Good to see some voice of reason in the general hubub over “saving the planet”.

    More than a few mentioned the greenish cast (C)FLs give to a scene.

    FWIW, CFLs and FLs give things a greenish tint because they produce light by a two-step process: ionizing Hg (mercury) vapor which produces blue-purple light and UV (ultraviolet); the phosphor inner coating of the (C)FL absorbs the blue-purple & UV and it fluoresces, re-emitting visible bright white light. An FL w/o the inner coating is aka a “black light”.

    As it happens, the spectrum of ionized Hg vapor also has two strong green lines, quite close together. These green emissions pass through the inner coating with some attenuation, but are still strong enough to distort the color “picture” we see.

  46. Since I didn’t want to buy a big LED for $80 last year at about this time, and then risk that the price drops drastically, as happened when I was an early adopter of CFLs, I bought 6 different small LEDs, nightlights, and a tree string, for fun, a year ago. I use the tree string for indirect lighting. It has worked fine for a year. It isn’t blue, but it isn’t warm either. It is the color of moonlight.

    I’ll tell you about my favorite LED though. It is a First Alert, (FH 2L) color change light, and consumes only one third of a watt. This light, if placed near a window, can function as a security light. How? From the outside, the color change looks like the kind of lighting change a room might undergo when someone opens a door. But I only use one of my bulbs for that.

    This particular light, my favorite, was only $5 at Walgreens. It is shaped like a tall Christmas tree light, and has bubbles in it (disperses the light randomly and looks decorative). It has an on/off switch, no auto sensor. It contains 9 LEDs, a set of three of each color (red, blue, green) and cycles between four basic colors, (all colors combined are white). The light flickers slightly, as it changes color, giving the effect of firelight. That is what I LOVE about it! It has the same soothing quality of embers glowing brightly, bursting into small flames. (Just the effect, the light does not make any flames.)

    If you can’t find this model, there’s a $5.99 color change light, with a light sensor (goes off in the day) that is made by First Alert also, and almost as nice, but it doesn’t flicker. So, without the flicker, it just doesn’t look as much like firelight.

    I use a FEIT LED color change nightlight in the bedroom, but it allows you to select the color, and red is nicest for a nightlight.

  47. So why not have specially made gypsum panels for ceilings with individual LEDs scattered throughout and a transformer in each panel. Should make getting rid of extra heat easier and give a nice, distributed light.

  48. As a lighting designer involved in several large hotels one major problem I have come across with LED’s is consistancy of colour temperature, whites of supposedly the same colour from the same manufacturer vary wildly. Plus, as they degrade (which they do, just cos it says it’ll last for 25 years, the output dips dramatically) they degrade at different rates, adding to the uneven look of large arrays of lights.

  49. well.. I DO have to say that every traffic light in the city of Austin works remarkably well with LEDs. Yes, pretty much ALL traffic lights in the city of Austin.

    How hard is it?

  50. Very good article, I think. LED lightning being used everyday to make our everyday gadgets more appealing. The cellphone, the computers, of course. Using LED lightning will greatly become more used when the public notices it’s wonderful uses.

  51. Great article!

    I agree that the LEDs available/affordable enough for the general public are not worth the money. Coloured decorative LEDs, yes, absolutely! So-called ‘warm-white’ retrofit LEDs, no.

    I’ve reviewed some energy savers here on my website. I recently sent for a Cree retrofit LED and was disappointed by the light quality: it was cool-pink rather than white and gave a markedly duller, greyer and more depressing light than my incandescent bulbs, even though it was better and brighter than most other LEDs I’d seen.


    Hopefully, I’ll find some better quality LEDs at the next Light Fair. But I still have my doubts as to how incandescent-like a light it is possible to make them without that element of fire.

    For those who still want an incandescent alternative for home environments, I would recommend the reltively new Halogen Energy Saver which comes in several retrofit bulb models. (No, I don’t sell them.)

    For retail environments I think metal halide discharge lamps give a bright, warm and good quality light.

    For street lighting, the warm-white version of those ceramic metal halide mentioned by mccrum, give a truly beautiful incandescent-like light while being about twice as efficient as standard mercury vapour street lights. I’ve not seen them used indoors but they may work well in retail too. I’ve yet to see an LED that looks remotely as attractive, but perhaps I’ve just not seen the higher end of the market yet.

    Saving energy and creating good lighting environments is a matter of choosing the right lamp for the right application. No one lamp type will solve all problems.

    1. Responding to Halogenica #71;;; you say that current LED’s are “not worth it” – I’m perplexed – we are all on this forum because of environmental and money saving characteristics of new lighting ideas.

      If we’ve got LED fxtures that use ~15% of the energy of incandescent, consider that at 100 watt bulb will cost ~$100 PER YEAR to operate if on 24/7 (at 12 cents per kWh). Even if you spend $100 on a high end LED fixture, you get full ROI in a little over a year – yes, if that is in a location where the light is on only 6 hours a day, then it takes 4 years to recoup, but still, that is pretty impressive.

      Worth it? Absolutely. It helps to run the numbers on the energy cost. Consider an industrial application like an airport bathroom, with 24 light fixtures (yes, I counted), all on 24/7/365. A large airport may have 100 bathrooms. If they can cut their lighting costs by 85%, or even 50% on conversion from fluor. to LED, the savings add up very quickly.

  52. I am a big fan of LED lighting. Choose a bulb that fits the application (lumens and color) and you will be happy. Unfortunatly many manufacturers and vendors overstate (I’m being kind here) their products specifications.

    I have purchased 45 LED bulbs and have had mixed reliability.
    The good news – some are very reliable. I have five LED bulbs outside that have run dusk to dawn for two years with no problems.
    The bad news – some bulbs are VERY unreliable. VERY high failure rates.
    I purchased 12 of one type LED bulb and 7 have failed (8.5W product 47856 from LEDLight.com). To make matters worse they are refusing to replace them now.
    Beware of LEDLight.com. This company is selling products that they know are defective. No support for failed LED bulbs. These bulbs are very expensive ($20 – $105) and in some cases last only two or three weeks. They refuse to replace defective bulbs. LEDLight.com is selling known defective products and has bad customer service.

  53. The Samsung “LED TV” is really a LED backlit LCD. It has much more contrast ratio
    than convention LCD tv’s and is extremely thin.

    Real high-def LED Screens are made by Daktronics and others but are huge, for
    stadiums and concert venues. They are amazingly bright and clear, but we will have to wait a while for a home-sized true LED tv.

    As for quality LED lighting, there are some dynamite products from Cree-LLF,
    including a Par 38 that provides halogen-quality light. (92 CRI)

    Philips Color Kinetics range of products are also super high brightness and quality, white, and RGB, as are the products from Renaissance Lighting.

    Prices are high, but are coming down almost weekly, and these product do live up to their claims of life and color and lumen maintenance.

  54. If that led is tiny, and it has to dump ~5 watt of heat, then it’s gonna get hot, and if not cooled well, really hot.

  55. Beautiful post, Maggie. Thank you!

    In this discussion of lighting quality, usually couched in terms of CRI, people have offered incandescent lighting as a standard, but few (none?) have mentioned sunlight. Some one hundred million years of evolution have adapted our vision to sunlight, with moonlight running a close second for naturalness. Humans have evolved with firelight for perhaps a couple million years.

    Fluorescent lighting and LED lighting (which itself has aspects of fluorescence in the case of white LEDs) lack fidelity to the standard of sunlight in many, perhaps unlimited, ways. In fact, as the Wikipedia article on Color Rendering Index mentions, it is difficult to even compare such light to the black-body radiation spectrum of sunlight or incandescent light, so CRI values have less meaning than you might believe.

    Our eyes have four color receptors (not neglecting the highly sensitive rods, you see), and any lighting system attempting to provide satisfaction must at the very least emit light that excites those receptors similarly to sunlight. The comments here on blue-yellow “white” LEDs reflect our reaction to this artificial spectrum, which has a single band to cover red and green alike.

    Perhaps future lighting systems will be adjustable, producing light that mimics sunlight, moonlight, firelight, according to the user’s desires.

    However, placing the emphasis on efficiency (“green lighting”?) will work at cross purposes to producing light of high quality. And be wary of any attempt (including the CRI) to reduce the measurement of lighting quality to a single number. Caveat emptor.

  56. We put 5 LED ceiling cans in our living room 18 months ago – $95 each from http://www.environmentallights.com/

    Performance has been flawless, no failures, nice clean light. Looks like very natural light to me – and I recall the claim was 12w equiv to 80w incand. output. 5 were fine for a 18×18′ living room. One more would have been nice, but not essential.

    I don’t have the specs or model # on them at my fingertips, but I am very happy with them and will be replacing the nasty slow to come up to speed CFL’s in the kitchen with LED’s very soon. The goal is to put the $$ into LED’s where we typically want ot have the lights on the longest, to get the best payback – and that is kitchen and living room. I can live with CFL in the abthrooms for the few minutes at a time I am in there.

  57. As an HVAC expert, LED’s can greatly reduce a buildings energy consumption because they run cool as compared to flourescent bulbs which need ballasts that run very hot and in a building like the one I work in that has about 5000 ballasts the heat load translates into additional tons of cooling capacity required and thats where flourescents loose in the efficiency department. Maybe in the future LED’s will be more reliable and less expensive. At that time, they will be a good alternative.

  58. Not just that but because of the heatgain produced through incandescent lighting often buildings require powerful ventilation systems such as air con which consume massive amounts of energy, that with inefficient and unreliable lamps and that require authorised personnel to change. The use of led light is indeed a wise one. Just if people can get past looking at the short term.

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