Study says LEDs are about as efficient as compact fluorescents, all things considered
By Donald Melanson 
posted August 5th 2009 5:03AM
posted August 5th 2009 5:03AM
As we've seen with the slight resurgence of new and improved incandescent light bulbs, the amount of energy used to actually light up the bulb isn't necessarily the whole measure of energy efficiency. There's also the small matter of producing the bulb, shipping it around the world, and eventually disposing of it. With that in mind, the Siemens Corporate Technology Centre for Eco Innovations conducted a study that compared regular compact fluorescents to LED lamps -- using one 25,000-hour LED lamp as a constant, compared to 2.5 10,000-hour compact fluorescents (and 25 1,000-hour incandescents). While it's still holding back on some of the finer details, the group did apparently find that LEDs are no more or no less energy efficient than compact fluorescents when the entire lifecycle of the bulb is taken into account, although it is quick to point out that LEDs should eventually win out as they become more efficient to produce.
Yes. But having to replace a bulb every 25k hours vs. every 1k hours is worth quite a lot to lazy people like me.
I'm a creature of the dark. My illuminated keyboard buttons are all I need.
@Kurian
So your screen doesn't have backlight at all?
@Tombio :
He has no screen, just illuminated keyboard buttons
@Kurian
You and me are from the same species I guess. The only thing that irritates me is people calling me "Nite Owl". Sad I know. Glad I'm not alone!
@ fikhl, nite owl sounds cool, u can be a nocturnal superhero or supervillain.
Don't believe for one second the claim of LED lamp life. Sure, it still may be illuminated at 50,000 hours, but what does that matter if it has a 10% loss in lumens at 5k hours, and then a 50% loss in lumens at 20k hours. 20k hours is nothing to scoff at, but it is not 50k hours.
This study also seems to be quite flawed when factoring a true 'apples to apples' comparison. When comparing identical color temperature to efficacy (lumen output to watt consumption) - LED fixtures are still quite inefficient. If it takes 3 $50 LED lamps to do the job of one $2 CFL - you have some serious hurdles when it comes to lifetime economics and payback.
I did a writeup on this very issue last month:
http://geekpi.com/?p=535
I just bought a handful of very interesting MR16 LED replacements - they seem promising when compared to the spotlight halogens they're replacing but they still suffer from a a relatively low efficacy of 35 lumens per watt. The T5 tube fluorescents we use for area lighting are over 100 lumens per watt.
LOLWUT?
The title, it makes me scream.
Yay LED's! Get cheaper already!
Not just the LEDs have to get cheaper. Unless they get a lot more efficient in lumens per Watt, much of the cost is the metal heatsink in a fancy shape.
As efficient than?
Um, and they don't dump mercury vapor when they break or are thrown away...
Another guy who thinks he will live forever...
Memento Mori
I certainly hope Bill doesn't procreate.
However, CFL's contain mercury,which is a healthe hazard when the glass breaks.
"No amount of mercury is good for you, but the very small amount contained in a single modern CFL is unlikely to cause any harm, even if the lamp should be broken" says the UK Department for environment, food and rural affairs (Defra).
http://www.rsc.org/chemistryworld/News/2008/January/07010803.asp
Whilst I agree that it is a health hazard, I think the hazard (in relation to mercury in Energy Saving Lightbulb CFLs) has been nicely hyped by various media outlets - so isn't quite as dangerous as its made out to be.
*Sigh* Then why do they recommend calling in haz-mat teams even on the label if there is so much as a hole in the glass?
@Matt
No hazmat required.
The EPA has guidelines on cleaning up CFL breakage and they don't include calling a hazmat team. I really don't understand the hysteria. I imagine most people who worked retail long enough experienced a burnt out full size flourescent tube being broken over someones head. Hell, they did it in 40 Year Old Virgin. Not smart, but I haven't seen an epidemic of mercury poisoning from it.
http://www.epa.gov/mercury/spills/#fluorescent
A CFL contains about 3x as much mercury as a can of tuna. And you put the tuna in your mouth ON PURPOSE.
The mercury in a CFL is frankly too little to actually care about, it only matters when disposing of it because they don't want the mercury accumulating in landfills.
you forgot to mention the electromagnetic radiation hazard from the CFL. CBC ran a story on it, and the canadian government started an indepth study on the subject. CFL emit something like 15-20 times more invisible, cell-phone like, rays than incandescant bulbs. CFL may become banned in a few years, once LED takes over. i would guess CFL is something like plasma tvs, in that they wont be around for much longer.
The amount of electromagnetic radiation given off by a CFL is miniscule. It's just a byproduct of the power supply in there. Trust me when I say your computer is topping the EM output of your CFLs by a mile.
I know I'm not alone in thinking that Engadget is really going downhill.
no you are not... the writing level is falling fast.
what do you expect from AOL, poster child for going downhill
by the way this is only saying that you are paying for the BULBS and how long they last before you replace them.
it doesnt take into consideration how far less it costs to run a .1w LED buld as opposed to a 100 watt incandesant or 20 watt CFL
These only shoot light upwards... or downwards in a ceiling light.
But regular lightbulbs shine light in all directions... great for a table lamp.
When will they make an LED bulb that has many LEDs to shine in all directions?
Phillips already do such a lightbulb -
http://www.engadget.com/2009/03/09/philips-master-led-light-bulb-set-for-us-release-in-july/
Not sure of its status though.
Then there's this:
http://www.engadget.com/2008/05/22/earthled-evolux-r-led-light-bulb-lets-you-choose-your-lumens/
and this:
http://www.engadget.com/2007/02/08/150-led-bulb-uses-9w-costs-65/
Michael, They do make LED's with wide angle dispersion of light! Just look at the beam width in degrees. 180 is hella nice! The bigger problem is the lumens! We need to up the brightness of LEDs. Note i myself have over 6 different types of LED lighting installed throughout my house - watched my electric bill drop $5 a month swapping out only a few main lightbulbs in my house
the title for this should be "led's ALREADY as efficient as compact flourescents, all things considered"
Why? The thought was that they were much more efficient. Or would you not be surprised by the headline:
"Study says electric cars are about as efficient as SUVs"
?
Because when you produce something in relatively small numbers it is not very efficient. it is a testament to the superiority (in terms of lumens/watt input) of LED bulbs that they can compete on an overall efficiency scale.
What about the the energy wasted in form of heat via stepdown transformer/converter or whatever it's called? BTW, there are already LED products that generate omni directional light similar to incandescent in the market I think. My personal belief is that in the foreseeable future, LEDs will only excel in hard-to-reach applications (like architectural lighting) and in situations where there's already 12V DC like in cars and electronics devices. Kick me in 5 years if that ain't so :)
One of the real problems is that the analysis depends upon a CFL lasting 10,000 hours. That is laughable. Due to high electricity rates in New England, I have lived with only CFLs in my house for 4 years. No way I get close to 10,000 hours out of a bulb.
Most lighting fixtures are not built to allow the heat produced by the CFL circuitry to escape, resulting in the CFLs overheating and dying in about the same time period as a normal incandescent bulb. One of my light fixtures repeatedly burned up CFLs every few months, with a couple of the CFLs looking scorched when I pulled them out.
The manufacturers need to do real world analysis, rather then keeping the bulb lit continuously in a refrigerated or air-conditioned chamber. Where is the truth-in-advertising? Save your receipts when you buy your CFL, because the manufacturer will replace them for you as long as you pay postage) WHEN they die early.
I suspect (hope) that LEDs don't have th eoverheating problem, so maybe in the long run will be more economical. Up-front cost is prohibitive, making them a non-starter at their current prices.
What's your experience with LEDs? Their real lifespan is much less than the stated one, too.
I speak from experience, that of my own, and many, many of my customers, who have tried LED, and decided it wasn't worth the expense.
Maybe you have bad fixtures or electrical. I've bought nothing but CFLs since 2003 through 2 apartments and 2 house and not one has burnt out.
LEDs actually last waaaaay longer than 25k hours.
The problem with current LED bulbs and fixtures is that they're all being overdriven. It's an universal practice to overdrive LEDs.
Two factors contribute to it: First, LEDs are still too dim, to get a good amount of light out of an LED fixture with the LEDs running at their recommended specs, on which they can get up to 70% of the original brightness after a cool 100k hours, would take quite a few LEDs in a single fixture, making it impractical because of size, and taking costs to a whole new level, to the point where no one would buy them. Have in mind that you also need to design the electronics to last long without losing precision, so no more using cheap parts.
Second, LEDs can be easily overdriven with no side effects other than a dramatically shortened life span, more heat, and maybe a bluish tint to the light.
On the other hand, I don't know if it's true, but I read somewhere that in most cases, the CFLs don't actually crap out, but the electronics in them do. Either way, they should do two more tests: One with proper CFL and LED designs, and another one with cheap consumer CFL and LED lamps, which I suspect are both very very different from the ideal designs. This study is somewhere in between.
(By the way, I'm assuming arrays of 1W LEDs. While there are more powerful LEDs, they tend to be very hard to deal with, heat management-wise, and hence only convenient for portable applications.)
Yes, BUT, LED can do all other kinds of zanny things, like being able to be dimmed and such.
I have dimmable CFL bulbs at my house. They are available, but more expensive. Also, they don't dim to the level a traditional bulb dims to.
I ran dimable CFLs in my house for about a month before they crapped out.
When it comes to illuminating my world, I don't give a damn about efficiency.
While many par30 CFLs are around 40-45 lumens per watt, we have dimmable led par30 lamps that achieve as high as 82 lumens per watt and are rated for 50,000 hours. The lamps are made by Array Lighting.
www.greenlightingsupply.com
making newer light bulbs more energy efficient is all well and good, however I'm still pretty upset that the gov't had to go and but the death sentence on incandescent bulbs. I have replaced most of my bulbs with CFLs, but there are still needs for incandescent bulbs.
25,000 hours is a low estimate for LEDs. They're also dimmable and don't contain mercury. LEDs should get cheaper when production ramps up and we can replace indium with graphene or something.
There are other advantages to LED's over CFL's. LED based fixtures don't put a huge inductive load on their circuits during startup like CFL's do. This means they can be used in places like outside lighting where the on/off cycle is usually controlled by a photocell on the house. LED's also don't have issues with startup when it is cold (as it is during the winter) making them the better candidate for replacing outdoor houselights.
Ah, we have an electrical engineer here! Yes, Power Factor is important.
A "13 watt" CFL actually puts a larger load on the grid than a "13 watt" incandescent night light. An easy way to explain it to people with EE degrees is think of electrical usage (watts) as voltage (pressure) and current (volume, or mass). A CFL draws unevenly from the "current" side and very little from the "voltage" side. The actual wattage (power) is the same for both bulbs.
So what's the difference then? Joule's law. Remember, some energy is lost in transmission as heat. This is defined by the equation heat produced = ((current)^2 * resistance * time)
Lets say that a CFLs pulled twice as much current from the 'current side' of the electrical transmission than an incandescent. This would mean a 2^2 = 4 joule increase. Lets say it was 4x, thats 16. A small change means a lot of wasted energy. Real world calculations show CFL's run a power factor from 30% - 50%, whereas incandescent and LED are close to 100%. UGGGGHHHHH! Thats a lot of wasted energy!
And before the EE's here jump down my throat, I know the explanation above is flawed. If you have a simple explanation thats more correct lets here it.
Jon,
The problem with your calculations is that it compares power consumption only. The real test is to compare units of brightness, lumens, per unit of power, watts.
LEDs use switching power supplies, switching power supplies work almost the same as the ballast in a CFL. And a switching power supply, unless there is extra circuitry to prevent it, runs at a poor power factor because it is an inductive load.
Jon:
A poor power factor doesn't automatically waste energy. The power companies have large banks of capacitors placed in proper locations to correct the phase differences. They're not stupid, they don't like to generate energy just to throw it away.
I just plugged in a couple of my CFLs to my Kill-A-Watt and checked the power factor. The PF on them is between 55 and 60%, just like any other device with an uncorrected switching power supply, like many computers (recent ones are PF corrected though due to European regulations). This isn't nearly as bad as 30%. You can expect an LED bulb to come out the same unless it also is corrected.
I do agree it sucks that non-resistive loads cannot be easily switched using a triac, but them's just the breaks I guess, it's unlikely any of our future lighting solutions will be plain resistive loads.
"And before the EE's here jump down my throat, I know the explanation above is flawed."
It sure is, Jon. No explanation is better than such an erroneous one.
"UGGGGHHHHH! Thats a lot of wasted energy!"
A reactive load doesn't waste energy, it simply stores and releases it.
"A CFL draws unevenly from the "current" side and very little from the "voltage" side. The actual wattage (power) is the same for both bulbs."
There is no such thing as drawing from the "voltage" side, in fact there is no "current" side and "voltage" side. Power is the product of voltage and current. The phase relationship between current and voltage is what is important.
There'll be plenty of lunatics on the other side to balance things out, I'm sure.
Incandescents can be made to last 25,000 hours too. By making the filament much thicker. However, this would mean that you need more energy to get the same amount of brightness.
The longest lit lightbulb is an incandescent lightbulb ... (over a 100 years continuously on), but it's got a fairly thick filament and is only 4 watts.
Throwing it in the back yard - how much does that cost?! Zero.