What's the brightest LED ? what's the chance they will replace Flourescent lights in

ikendu

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

I notice that Advance Mart sells these "25 watt" replacement bulbs that only draw 2.5 watts.

http://store.advancedmart.com/11acsc34whle.html

Compact Flourescents use about a 1/4 of the power of an incandescent, apparently LEDs draw about a 1/10th. ...and, LEDs aren't done yet with improvements or innovations.

I do think that in 10 years, maybe most houses will be set up to use LEDs.

If nothing else, the increasing costs for energy will start drawing attention to these technologies.
 

Sleestak

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

ikendu said:
I do think that in 10 years, maybe most houses will be set up to use LEDs.

If nothing else, the increasing costs for energy will start drawing attention to these technologies.

The only way I see LED's making strong inroads into the home lighting market is for their price to come down substantially. Right now, trying to purchase an LED bulb for the house is prohibitive costwise, especially considering the performance.

Also, Flourescent technology is really coming on strong right now. Used to be you could go the the local Home Despot and find a small row or two of flourescent screw in bulbs. Now, you can go and find pallet stacks of them. So, I think that flourescent technology will generally rule for the upcoming future; however, I do think that LED technology will come along strong, and will become the 'new thing' that replaces flourescents at some point in the future. It will also come down to someone coming up with more or less of a 'Mazda bulb' standard so that all LED's perform similarly regarding color hues. Nobody wants to light their house with cold colors. Someone'll have to come up with nice sunlight hues first. That's what's pushing flourescents a little right now, that they can come in warmer colors than once they could.

It's kind of exciting, really. I'll be cuing up for LED fixtures just as soon as they get better pricewise.
 

joema

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Even the most efficient white LEDs can't match current fluorescents. The above mentioned Osram Ostar has lots of output, but is apparently not an efficiency leader. Whenever Osram releases a datasheet we'll know for sure, but I've seen one source saying it's 40 lumens per watt.

The most efficient LEDs produce roughly 60 lumens per watt, but that's typically when underdriven so light output may not be useful. When normally driven, efficiency typically drops by about 1/3 to 1/2, or around 30-40 lumens per watt. More details in this thread: http://candlepowerforums.com/vb/showthread.php?t=96915&highlight=sphere

By contrast compact fluorescents reach about 70 lumens per watt, and T8 fluorescent tubes can reach about 90 lumens per watt, including ballast losses.

There's also a big difference between the efficiency of current shipping residential LED fixtures vs the datasheet efficiency of discrete LEDs. Current shipping fixtures are often around 25 lumens per watt, which may include transformer/rectifier losses.

So in a commercial or residential lighting application, current shipping T8 fluorescent tubes (inc'l ballast losses) have about a 3x efficiency advantage over the best discrete LEDs when normally driven, about a 2x efficiency advantage if the LEDs are under driven, and about a 3.5x efficiency advantage over current shipping residential LED fixtures.

Efficiency of LED residential fixtures will probably further improve, but they have a long way to go before matching the best current fluorescent tubes.
 

LEDninja

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Take a look at this thread. Nice pictures by a CPFer who converted his home to LED lighting.
http://candlepowerforums.com/vb/showthread.php?t=98986&highlight=led+household+bulb

My post (#7) has the lumen ratings for compact flouresets and also show the equivalent incandescent bulb.

WARNING
NONE of the LED bulbs I purchased are UL listed nor CSA approved. All 115 volt equipment should be tested for fire and electrical shock safety, and the approval stamp should be on it. Equipment 24 volt and under (that's most flashlights) are not required to be tested.
There was a recall of LED Christmas lights in Novia Scotia due to fire hazard from a faulty component. (And those lights were previously CSA approved)
 
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Cavannus

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

Comparaison between incandescent, fluorescent and led lighting is not so easy...

First, there is a psychological effect, and according to Kruithof's curve, for a same subjective perception of comfort (and a good comfort is often perceived as a good light output... yes!), actually less "warm" light output is needed than "cold" light output.
(http://www.learn.londonmet.ac.uk/packages/clear/visual/people/ambience/colour/)


So, incandescent lamps have a poor efficiency, but as the light seems "warm" (3000 K), this "pleasant" efficiency is not perceived as so bad. On the contrary, a led beam may seem not very bright because its color temparature is "cold" (6000 K).
Subjectively: "not pleasant" is perceived as "not good", and at the end "not good" is perceived as "not bright enough"...


Second, for an identical overall flux, light distribution is not the same for incandescent/led and fluorescent.
Incandescent and led allow to use a reflector, and the narrow beam will give a perception of a bright source.
Fluorescent, despite its very good efficiency, does not allow to use a beam, so :
- for low intensity lamps (flashlights), much light is "lost" so it doesn't seem powerful nor bright at all => led seems more efficient, more brighter (in subjective terms);
- for high intensity lamps (indoor lighting, at home or at the office,...), where general lighting is required, fluorescent lamps give much homogeneous light, so they seem brighter than leds or incandescent.

Third, don't forget life duration... Many lighting system efficiency decrease after a few hours: it is bright in the shop, it is poor at home... Especially when fluo or led lamps are boosted!

I hope this will balance the objective (true) values given above, and help to understand why a fluorescent flashlight seem less bright than a led flashlight, despite lm/w efficiency values.

(And sorry for my English, this is not my mother language)
 
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jtr1962

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

Sleestak said:
Nobody wants to light their house with cold colors. Someone'll have to come up with nice sunlight hues first. That's what's pushing flourescents a little right now, that they can come in warmer colors than once they could.
Sunlight = ~5000K, incandescent = 2700K to 3000K. I agree that most 5mm LEDs are too cold to light a house with, coming at at 8000K and up. However, I'm starting to notice a surge in popularity of so-called sunlight fluorescents which will hopefully soon carry over to wider availability of CFLs in 5000K instead of the more common 2700K or 3000K. Sure, 5000K is somewhat "colder" than your average incandescent, but don't go on the blanket assumption that "nobody" wants anything but incandescent-like lighting in their homes. I personally can't stand incandescent lighting (and I wouldn't like 8000K LED lighting much either) but I find 5000K very nice.

What's helping fluorescents more right now isn't necessarily that they can come in warmer colors (they did have a so-called incandescent fluorescent years ago but it was even more horrid than the cool whites of the day) but rather that their color rendering has improved greatly over the horrid standard greenish cool whites from years ago, plus electronic ballasts have eliminated flicker. Those were the usual drawbacks most people complained about when asked why they didn't use fluorescents. However, I think the CFL manufacturers misinterpreted people a bit when they may have said "the color is all wrong" or something similar. They thought the people meant that the color was wrong because it wasn't like incandescent instead of meaning the color was wrong because some colors were missing or distorted. As a result, early Energy Star legislation more or less dictated CFLs with color temperature similar to incandescent, supposedly to increase acceptance. IMHO, this is exactly the reason they're still not terribly popular even though they are catching on. Quite a few of the potential early adopters of CFLs didn't want to spend $20 on a bulb which gives light exactly like the incandescent they were replacing. While the energy savings was certainly an attraction, a more immediate benefit would be more natural (i.e. closer to sunlight) lighting. Indeed, even before the first energy crisis got people interested in fluorescents there were a fair number of people who used them in their homes precisely for better lighting. As strange as it may sound, I personally preferred even the old school cool whites on a magnetic ballast to incandescent which I always found horrible, even as a kid. Anyway, yes, most of the CFLs these days are still the horrid warm white but I've noticing a gradual interest in 5000K sunlight. Daylight is also finding a niche, although for many people the jump to 6500K is just too much to tolerate in one shot, which is why it hasn't really taken off.

I'm personally looking forwards to the day, hopefully within 5 years, were reasonably-priced LED incandescent replacements start to make their way to the shelves. More recently Energy Star legislation simply requires that bulbs be labeled with their color temperature and thus has no bias to warm white as the old legislation did. This and gradually changing preferences will hopefully mean LED replacements will be readily available in 2700K, 3000K, 3500K, 4100K, 5000K, and 6500K so the end user can pick whatever suits them. Incidentally, it seems within LED circles that 3500K is becoming a sort of new standard for "warm white", implicately acknowledging the trend I'm seeing towards lighting the home with whiter light. Remember that incandescent never was ideal or even close to it. It was merely all we had for a long time, and people simply got used to it, just as they had been used to candles when they were in use. Another topic entirely there, namely how quickly people can get used to, even prefer, something that isn't necessarily optimal, or even close to it.
 

jtr1962

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

Cavannus said:
First, there is a psychological effect, and according to Kruithof's curve, for a same subjective perception of comfort (and a good comfort is often perceived as a good light output... yes!), actually less "warm" light output is needed than "cold" light output.
This isn't what Kruithoff's curve tells us at all. Rather, it tells us that at lower lighting levels what is perceived as pleasant will have a lower color temperature than what is considered pleasant at higher lighting levels. From a practical perspective, this means that higher color temperature lighting needs to have higher intensity to "feel" right. Note that this has nothing to do with the light being good for seeing or considered "good light output". It is merely that psychologically at low light levels high color temperature lighting "feels" wrong even though it is actually better for visual acuity, and you need fewer photopic lumens to perform a given task because of this. Candles or dimmed-down incandescent might be perceived by many people as creating a relaxing atmosphere at low light levels, but the color (and light level) are horrible for actually getting anything productive done.

Subjectively: "not pleasant" is perceived as "not good", and at the end "not good" is perceived as "not bright enough"...
The first part of the sentence is correct, but it's a bit stretch to come to the conclusion that "not good" is perceived as "not bright enough". In general, a person will only complain about light levels if they're not adequate for the task. They may complain the light feels wrong if the color isn't to their liking, of course, but I've yet to hear a person say a room lit with a few LEDs isn't bright enough because the light isn't pleasant to them while one lit with an incandescent night light bulb is bright enough because they like the light. Rather, they will only complain the room is too dim if they can't perform whatever task they're trying to accomplish, which in this case might simply be moving around the room without banging into things. For a given lumen level, the LEDs would actually be superior in that regard owing to their scotopically superior spectrum even if they might not be perceived as pleasant.

One thing I find very suspect about Kruithoff's curve are the findings at very low light levels even if the findings are fairly valid at higher light levels. Supposedly the preference tends towards 1500K (candlelight) at these very low light levels (1 lux and under) but the fact is that at these same low light levels your eyes are incapable of distinguishing color at all, so how can you have any color temperature preference if you're not seeing color? If anything, what is perceived as the best light at these low levels should be whatever type of light best matches our scotopic sensitivity. For those reasons I think with a proper test the color temperature preference would start back up again at a few lux since higher color temperature lighting would be perceived as brighter at low light levels compared to the same intensity of low color temperature lighting. Furthermore, eventually at extremely low light levels there should be a marked preference not for white light, but for monochromatic cyan, since this color is at the peak of scotopic sensitivity. Note that at these low light levels the person wouldn't even be aware that the light is monochromatic since they aren't seeing in color, but merely that it seems brightest. Yes, at very low light levels brightness and pleasantness are indeed interchangeable since there is no other basis for perception due to the fact that color vision is inactive. However, at higher light levels these terms are not interchangeable. A person may indeed say a light which they don't find pleasant still appears brighter than one that they like.
 

EricB

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

However, I think the CFL manufacturers misinterpreted people a bit when they may have said "the color is all wrong" or something similar. They thought the people meant that the color was wrong because it wasn't like incandescent instead of meaning the color was wrong because some colors were missing or distorted. As a result, early Energy Star legislation more or less dictated CFLs with color temperature similar to incandescent, supposedly to increase acceptance. IMHO, this is exactly the reason they're still not terribly popular even though they are catching on. Quite a few of the potential early adopters of CFLs didn't want to spend $20 on a bulb which gives light exactly like the incandescent they were replacing. While the energy savings was certainly an attraction, a more immediate benefit would be more natural (i.e. closer to sunlight) lighting. Indeed, even before the first energy crisis got people interested in fluorescents there were a fair number of people who used them in their homes precisely for better lighting. As strange as it may sound, I personally preferred even the old school cool whites on a magnetic ballast to incandescent which I always found horrible, even as a kid. Anyway, yes, most of the CFLs these days are still the horrid warm white but I've noticing a gradual interest in 5000K sunlight. Daylight is also finding a niche, although for many people the jump to 6500K is just too much to tolerate in one shot, which is why it hasn't really taken off.
I always hated the brown incandescent light, and wished they would have cool white in a bulb. (I wanted mercury bulbs, until I found that they needed ballasts, even if they weren't large base size). So when CFL's first came out, that seemed the answer, except for the cost. By the time the costs came down, and they were more readily avaiable, almost all now emulated incandescent color. Actually, even though this is now called "warm white, this is really soft white, and "warm white" was the first attempt of CFL's to try to emulate incandescent color, with a sort inbetween hue that was paler than incandescent. I believe this color was in the 3000's K, and was basically close to what is called "lunar white". But then they "perfected" the incandescent color, and "daylight" became hard to find. I always wondered why they had to copy the quaint old incandescent color, and when I heard people say it was easier on the eyes or something like that; I figured that must be why. I didn't know that it was mandated that they be that color. I guess I could see why warm tans would be preferable for reading (I just liked the bluer whites because they were different, and "modern" looking). But as you said, I guess something in between, that more emulates sun color would be best.

I gradually replaced all the lights in my apartment with CFL's, and hunted to find some daylights for the kitchen (because I was used to cool white Circlines in kitchens; soft white doesn't look right), and the bathroom because it has a nice two tone blue tilework which looks better with daylight, and also the bedroom, because I always wanted daylight for the bedroom.

Now, they have LED's that exactly match incandescent color, but they don't seem to be catching on. You would thin they would immediately take over LED flashlights, but all the ones I've seen use the bluish white.
 

jtr1962

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

EricB said:
I always wondered why they had to copy the quaint old incandescent color, and when I heard people say it was easier on the eyes or something like that; I figured that must be why. I didn't know that it was mandated that they be that color.
It wasn't mandated in so many words that CFLs had to be warm white so much as they had to have a certain CCT range (2600K to 3100K IIRC) to receive the Energy Star label, or if not within this range they had to be labeled "Daylight". That pretty much left the consumer with only two choices-warm white which many felt was too yellow, and daylight which was sort of a catchall for anything which wasn't in the CCT range I mentioned earlier. As a result, since "daylight" fluorescent had traditionally been 6500K this was what most of the daylight CFLs were, but you could also package 4100K, 5000K, or for that matter even 8000K as "daylight". That's another thing which hurt the sales of daylight CFLs-unless the package was labeled with a color temperature, which by law it didn't have to be, it was a guessing game as to what hue you were actually getting. At the $20 a pop early CFLs sold at, nobody wanted to play such a guessing game. Later Energy Star legislation corrected this problem by simply requiring that the CCT be on the package. This practice has carried over to linear tubes as well. I no longer see tubes solely labeled as warm white, cool white, or daylight. These terms still appear on the packages, but so does the CCT.

Someone here once linked to the old and new Energy Star legislation but the search function still isn't working particularly well. If I saved these documents on my hard drive I'll post the relevant paragraphs here.

Now, they have LED's that exactly match incandescent color, but they don't seem to be catching on. You would thin they would immediately take over LED flashlights, but all the ones I've seen use the bluish white.
Which only proves that incandescent was never really ideal, and even less so in something like a flashlight were the crispness of the light takes precedence over all else. I'll go out on a limb here and say that except among lighting designers who can't fathom the idea of people wanting something other than warm light in their homes, warm-white LEDs will continue to be at best a niche market even once LEDs start to take over general lighting. I may be wrong of course, but I'm seeing more and more studies suggesting sunlight-like lighting is actually better for long-term eye health, especially when one does a lot of close work. In my walks I'm also seeing more and more family rooms, dining rooms, etc. lit these days with high CCT fluorescent lighting instead of the traditional warm lighting usually used in these rooms. It can't be that these people are all CPF light connoisseurs. ;) More likely they went through the same things you and I did, and simply found they liked cool lighting better
 

Cavannus

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

jtr1962 said:
This isn't what Kruithoff's curve tells us at all. Rather, it tells us that at lower lighting levels what is perceived as pleasant will have a lower color temperature than what is considered pleasant at higher lighting levels. [...]
Indeed, you're right... but this is only one way to see the curve. In fact, as you say, on two axes (intensity and light color) the curve means the point where both axes are comfortable. Follow the curve, and you'lle see that I'm right, as you are too! It is also possible to "reverse" the curve and to put "comfortability" on an axis...


jtr1962 said:
From a practical perspective, this means that higher color temperature lighting needs to have higher intensity to "feel" right. Note that this has nothing to do with the light being good for seeing or considered "good light output". [...]
I agree!

jtr1962 said:
The first part of the sentence is correct, but it's a bit stretch to come to the conclusion that "not good" is perceived as "not bright enough". In general, a person will only complain about light levels if they're not adequate for the task. [...]
Believe my ergonomist experience: people are not able to express why a light system doesn't fit with their task. They may complain about the light color or the light quality, even if this is mainly a problem of intensity! They may really say "the light is sad, not very nice, like a old fluorescent tube" whereas it's only a question of light output!


jtr1962 said:
One thing I find very suspect about Kruithoff's curve are the findings at very low light levels even if the findings are fairly valid at higher light levels. [...]
Personally I only interpret this curve in relative terms. Again because psychological effect. For example, for the same perception of sufficient output, more output is expected in a room than in a cave or in the street... In the first case 300 lux are required, in the two other cases, 10 lux are enough...

For me, very low levels are out of scope.
 

LEDninja

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NewBie said:
An article on those guys. Looks like they are doing ceiling fixtures for now.
http://www.newsobserver.com/104/story/393185.html
54 lumens/watt is impressive. Especially since they are using warm white.
900 lumens for 13 watts measured at the plug.
My '13 watt' compact flouresent is listed 800 lumens on the package. Power usage is 210mA at 120volts or 25.2 watts measured at the plug.
So those LED lamps are almost twice as efficient as compact flouresent with similar output.

LEDmuseum got some bulbs for review.
http://ledmuseum.candlepower.us/fifth/rlbulbs.htm
 

jtr1962

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LEDninja said:
My '13 watt' compact flouresent is listed 800 lumens on the package. Power usage is 210mA at 120volts or 25.2 watts measured at the plug.
The volt-amps are more than the watts because the power factor is less than one. Look at the labels on air conditioners. You get the same thing. If you multiply the volts and amps you end up with a higher number than the labeled rating in watts. Your CFL does indeed draw 13 watts, not 25.2 so its overall wall-plug efficiency is 61.5 lm/W.
 

jtr1962

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Re: What's the brightest LED ? what's the chance they will replace Flourescent lights in

Cavannus said:
Believe my ergonomist experience: people are not able to express why a light system doesn't fit with their task. They may complain about the light color or the light quality, even if this is mainly a problem of intensity! They may really say "the light is sad, not very nice, like a old fluorescent tube" whereas it's only a question of light output!
I'm really surprised that adults would use terms like that to evaluate a lighting system. Saying "the light is sad" sounds like something a 5-year old might say. And there's still that negative association of bad lighting with fluorescent despite the fact that the old drawbacks no longer exist.

I also question the methodology some of these lighting designers use for the comparisons. For example, they'll compare an incandescent with a poor color rendering old-style cool white tube on a magnetic ballast and then draw the conclusion that most people don't like high color temperature lighting. Truth is that their own bias towards warm lighting made them set up the test in such a way as to guarantee the outcome they wanted. Try the same test using high color rendering 5000K lamps instead and I beleive the results would be very different. You'll probably get a lot of people say "I like that lamp better. It looks more like sunlight than the incandescent."

Personally I only interpret this curve in relative terms. Again because psychological effect. For example, for the same perception of sufficient output, more output is expected in a room than in a cave or in the street... In the first case 300 lux are required, in the two other cases, 10 lux are enough...
At 300 lux the mean "pleasant" color temperature is actually roughly 4000 to 4500K. Truth is most people light their homes like caves, so more likely lighting levels are closer to 10 lux. I don't consider a 100-watt bulb in a lamp which shades out half the lumens to be adequate lighting, yet a lot of the general public uses exactly that. Maybe with LEDs we'll be able to economically have brighter lighting levels eventually and that will by extension lead to higher color temperatures.
 

NewBie

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LEDninja said:
An article on those guys. Looks like they are doing ceiling fixtures for now.
http://www.newsobserver.com/104/story/393185.html
54 lumens/watt is impressive. Especially since they are using warm white.
900 lumens for 13 watts measured at the plug.
My '13 watt' compact flouresent is listed 800 lumens on the package. Power usage is 210mA at 120volts or 25.2 watts measured at the plug.
So those LED lamps are almost twice as efficient as compact flouresent with similar output.


It is interesting to note that the CRI for these new LED bulbs is 93% vs. 65-82 for most CFLs.

Thats much better.
 
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NewBie said:
It is interesting to note that the CRI for these new LED bulbs is 93% vs. 65-82 for most CFLs.

Thats much better.

Reference?

You can reach a CRI of ~95 or ~100 lumens/watt, but not at the sametime.
A 32W 4' lamp can make 3,100 lumens with the CRI of 86, but if you get a 92 CRI lamp, you will only get around 2,000 lumens.

With the 8 ft fluorescent, you can reach ~100 lumens per watt using the best ballast while making around 5,000 lumens per lamp and a CRI of 86.

These lamps maintain 95% output after 10,000 hours.

You can get them in 3,000, 3,500, 4,100, 5,000 and other color temperatures depending on market demand and the color is extremely consistent within a lot. From batch to batch, there might be a slight variation, but you really have to look for it to see the difference.

The disadvantage is reduction in life with frequent switching. Cost per lamp is $5 or less in the typical quantity they're used in, which comes to less than a dollar per thousand lumens.
 
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