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Sunday, February 22, 2009
LEDs for lighting: Efficiency is not enough
Feb 22 2009 12:07PM | Permalink | Email this | Comments (38) |Blog This! using:  Blogger.com | LiveJournal |Digg This | Slashdot This | add to Del.icio.us

What is the world’s appetite for light? What if an increase in lighting efficiency does not result in less energy consumed, but in more lighting used for the same amount of energy? This question was posed by Jeff Tsao, a researcher at Sandia National Labs, who studies the technology and economics of lighting. He gave a summary of his research and analysis on the implications of lighting efficiency at the opening session of the Strategies in Light conference last week.
Tsao looked at data on the consumption of artificial light worldwide for the past three hundred years, which covers the introduction of five different lighting technologies: candles, kerosene, gas, incandescent, fluorescent/ high-intensity discharge.
Over the past 300 years the world has spent a constant 0.72% of its gross domestic product (GDP) on artificial lighting. This observation (and it’s an observation, not a law) translates in the US to the equivalent of 17 100W light bulbs turned on during the waking hours of every person, while in Africa the usage is the equivalent of one  ½W light bulb burning for every person’s waking hours.
But how does this relationship between GDP and lighting usage account for increases in the cost of energy (COE)?  COE affects the lighting usage equation by driving down the GDP. That is, people will consume less energy for lighting only if the COE increases or their standard of living in general goes down, not because lighting becomes more efficient. As lighting because more efficient – that is, it becomes cheaper – then lighting usage will go up. This follows intuitively from knowing that in general people consume more as things’ costs go down, which is what happens when lighting becomes more efficient.
So is the move towards LED-based solid-state lighting really an effective strategy to lower energy consumption? Maybe, but only if it’s paired with an increase in productivity.
COE plays a major role in GDP, but it’s not the only factor: Another way to increase GDP is to become more productive. Throughout history, lighting has helped productivity. As lighting technology advanced (kerosene to gas lamps to electricity), lighting became cleaner, took less time to turn on/off, room heating decreased, and fire hazards decreased. The conclusion Tsao reached from his study is that efficiency alone will not result in a decrease in energy consumption: It must be accompanied by an increase in productivity.
Here’s a likely conclusion we can draw based on this study: The killer app for LEDs  is not going to be a replacement bulb for 40W home lights – that’s not going to increase anyone’s productivity. The opportunities for LED lighting will be in applications that have inherent intelligence, and can interact with their environments and humans in ways that make both of them more productive and intelligent.
Interested in how LEDs will acquire intelligence and enhance productivity? Attend EDN’s free LED Workshop, April 30th, in Santa Clara, CA.
Related entries in: Displays and indicators | Power Sources/Controllers |

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at 2/23/2009 2:56:15 PM, RD said:A very interesting article. I can relate to it in that I have a solar powered vacation home. When I first started using solar power, I was more conservative in lighting since all the lighting was incandescent and low efficiency. As CFL lighting became practical, I changed over, increasing the amount of lighting but within the same available power limits I had previously observed. The same thing happened in video projection systems with the advent of high efficiency discharge sources. Pictures just got larger and brighter but projector power consumption didn´t change that much. at 2/23/2009 2:57:45 PM, Policebox said:You forgot that there is an upper limit to the amount we are able to use. After that people will stop paying more for lighting because it doesn´t give them any return. That the 0.72% rule still holds only says that limit isn´t reached yet. However, there are some rumblings that it may be getting close. Light pollution is becoming an issue, and that has to be the first step. at 2/23/2009 3:06:00 PM, al said:The flaw in Tsao´s analysis is the underlying fact that the reason people used more lighting when it became cheaper is that lighting never reached the saturation level. Tsao assumes there is no limit to the amount of light people desire. Once the lighting becomes sufficient for all possible needs then there is no benefit from adding more. With flourescents and high intensity discharge, we are close to saturation in the amount of lighting required. So making lighting cheaper will not follow the same pattern seen with earlier forms of lighting. at 2/23/2009 3:14:09 PM, ron said:how dumb can you be?? at 2/23/2009 4:27:34 PM, karl said:Does LED is really much more efficient than discharge lamps? I doubt it... at 2/23/2009 4:27:35 PM, LChien said:very intersting article and presumption. I suppose mankind is the better for increased use of lighting - our productivity hours have increased. I suppose cheap intelligence built into lighting products (the lights sources themselves?) may become necessary for real energy savings (unless as pointed out by some respondents that there is a lighting saturation point) timers, people sensors, ambient sensors. timers for example tend to get off and become coumterproductive, so do we put timereceivers (over the powerline) or GPS and knowledge of the time of year and Latitiude has to be entered? how cheap can we make these things? at 2/23/2009 4:30:11 PM, karl said:Excuse my error...I meant does LED really run much more efficient than discharge lamps....I doubt it. at 2/23/2009 4:32:11 PM, Martin Hall said:I saw that talk, too, and one of the things I took away was that--as is common with this sort of log-scale plotting--small differences in large numbers (such as the amount of light we use per-capita today) are lost in the noise when compared to the orders-of-magnitude differences along the whole scale. That means that a factor of two improvement in current-day lighting cost would be almost imperceptible in his plots, even though it would save billions in absolute terms. It was an interesting talk, but I didn´´t find it to support the productivity argument at all--the numbers are just too noisy. at 2/23/2009 4:40:28 PM, Drdave said:People need to be more skeptical of the LED claims. Even the mediocre white LED sources use double the electricity of tube fluorescent. ~50 Lumens/watt for LED versus 108 for "Normal" good Fluorescent and 75 as a legal minimum. Your analysis of price is correct, but Fluorescent is now lasting 46000 hours from all the major manufacturers at a cost of 3 dollars. The Hurdle that LED will face is the fixtures not the sources. Try to convince someone who owns a strip mall of rental space to rip out all of those 4 foot fixtures and replace them for rental spaces...NOT going to happen. LED will be big in New Construction. I attended the last global summit and the white LED (Blue LED with phosphor modifications) BEST in class was around 60 Lumen/watt. Not commercial yet. The Phopshor efficiency was 93% so there is only 7% better it could even theoretically get! That is the dirty little secret about LED it is an energy PIG. Measurement is instant light output (50 milliseconds) before the chip heats up and the output falls 40% but nobody is making them present sustained output . Go to Sams Club and pick up a package from Lights of America - there is all sorts of comparisons to incandescent Wattage, but nowhere does it tell you how much light (lumens) you get. You could assume that the little LED candleabra bulb that uses just 1.5 watts and replaces a 40Watt incandescent is apples to apples on light output but that would be wrong. You actually only get 1/4 the light of the incandescent. at 2/23/2009 5:02:22 PM, Al Cyron Lighting said:I do not agree with Mr Tsao logic. I did not go out and replace my old refrigrator with several energy efficient models. I replaced it with ONE. However, I do agree with him that in addition to lowering energy consumption, Solid-state lighting provides a great advantage over traditional lighting sources due to its ability to redesign light sources. A good portion of light pollution and waste of energy has been due to the fixtures that had to be designed with omni directional heating elements AKA light bulbs. at 2/23/2009 5:32:50 PM, Bob said:The figures reminds me of the marketing wars for audio amplifiers when I was a kid -Headline 1000 Watts power! In small print peak to peak at 100% THD, true useable figure more like 30w RMS at 0.1% THD. Same with lighting installed a new kitchen four spot LED ´equivalent´ of 100w - family after suitable eye tests demanded replacement with ´Proper lights´! LED lighting has its place, but its nowhere good enough to replace tungsten or Fluorescent and it won´t save the planet.... at 2/23/2009 5:55:47 PM, Brad Wood said:It will take a while, but LEDs are progressing rapidly. If properly used they should create much less electrical interference than CFLs, and have far less propensity to pollute upon disposal . For new construction one could distribute d.c. and have purpose-built fixtures. With multichip arrays one could fine-tune the color for a variety of interesting effects. I´m for them, in time. When I read this appalling number of 17 100W bulbs burning for each person´s waking hours I wonder where and how people are doing this. But then there is the counter factor with incandescents and CFLs alike, which is that too-frequnect cycling leads to premature failure, so that could be part of the reason for leaving things on. I am rather reminded though of the lyric in "The Last Time I Saw Richard", the old Joni Mitchell song, where she sings "he drinks at home now most nights with the TV on and all the houselights left up bright". Maybe we need to be a little less scared of the dark, at least of it in rooms not in use ;) at 2/23/2009 7:52:55 PM, Andy George said:LED lighting alternatives should be developed and tested by free markets instead of the 2012 laws enforcing the replacement of existing lighting. The upcoming litigation predicated on a theoretical technologies looms on the horizon like some photon breathing dragon scorching all who wish to see. Planners who know what´´s best for us have latched onto the green bandwagon of efficiency blinded by extreme practicality and by the need to burry previous CFLs failures. More focused applications of LED lighting in smaller areas have proven successful. But large scale lighting requiring high saturation and efficiency are far off as of now. Forcing everyone to buy into the development of future LED lighting before it even exists is the sure fire way to keep us all in the dark. Just imagine what it´´ll be like with everyone trying to see by the same mediocre, off color, overpriced government LED lamp. As if CFLs aren´´t annoying or toxic enough! at 2/23/2009 8:01:48 PM, Martin Hall said:While it´´´´s not clear that the appetite for light is unlimited, we DID evolve in sunlight, which is orders of magnitude brighter than most interior lighting, and does make some things easier. Certainly as I get older, I need brighter light for many things, and I deplore the tendency to reduce wattage of, say, bedside reading lamps in the name of "efficiency". One thing we will eventually get from LEDs is good brightness control over a wide range. Lights that can react to the need for brightness and supply it when appropriate will be a big help. LEDs can maintain color and quality, and even become more efficient when dimed, unlike incandescent or fluorescent sources. at 2/23/2009 10:00:19 PM, transformer insider said:Check out lemnislighting´s product for LED lightbulb. 60 watts of brightness on 4-5 watts of power. Good power factor, good life, good color (finaly) and not so projection like as previous LED bulbs. European voltage model is being built for the Netherlands and US version is being developed. Price is high but will come down. at 2/23/2009 10:34:59 PM, Mr. Green said:I am not the LED expert. But, I am interest to found out anyone done this experiment before 1) Prepare the same brightness rating on the LED light, same Lumens with flurescent. 2) Use the same type of battery (full charge) and measure how long it take to drain out. 3) If there is no buildin DC-AC on the fluorescent. We may need to ignore the efficient drop on the DC-AC conversion (e.g. 3~5% loss, I assume) 4) In this case, we should able to calucate what is the efficence different between LED and fluorescent light. at 2/24/2009 1:29:56 AM, Ramelda Amir said:The last sentence says there is a lighting application that can make humans more intelligent. Am I missing something or is this the complete nonsense it sounds? at 2/24/2009 2:47:02 AM, PeterS said:Tungsten 12 to 18 lm/W Fluorescent 44 to 70 lm/W (cheap lights gave 44, best quality gave 70) LEDs are capable of well over 100 lm/W, but those are too expensive to use in retail lighting. IF they ever get the pricing right, LEDs will take over. Oh, and 1000lux is a really nice bright cheerful light level, and that is expesive to maintain at the moment at 2/24/2009 5:47:53 AM, Charles G. Nutter, Silacon.com said:I delivered my thesis at Caltech-JPL 1993 covering the very subject of HID, CFL devices and systems later extended to LED intelligent lighting devices and systems. The paper explained my very high efficiency AI managed system that minimized costly SMPS electronics and added functionality. HMM, Bayes, and recurrent NN with GA became the intelligent systems components. The LED systems developer must include an optimization mathematician well versed in DOE (Design of Experiments). I included observations of Dr. Oliver C. Morse (UC Berkeley-LBL) and Professor John Clegg (BYU-DOE Gold Award winner). I think anyone interested in the truth about LED systems must consult with Oliver and John. I pointed out in the paper the advantages of intelligent lighting that could go far beyond only lighting by incorporating wireless and wired communications, sensing, point of use automatic lighting, all systems having artificial intelligence processors interfaced to other systems in buildings or mobile settings. I constructed a prototype CFL and HID distributed lighting system operating 15 100 Watt light sources from one intelligent ballast demonstrated at Emerson Electric. Nowadays, the electronics to produce intelligent systems is cheap. I wish that Tsao could have been my partner. Tsao is aware of the non-linearity and boundaries of the observations. His point is well taken. Efficiency is not enough regarding power input vs. lumen output. LED lighting must have a higher calling to limit energy and usage abuses. Talk to John Clegg (BYU) and Oliver C. Morse at Lawrence Berkely Labs. at 2/24/2009 5:49:02 AM, Bally said:Notice how the LED replacement lights sold side-by-side with CFL´s at Sam´s Club are not shown lit? They cost more and the light output is useless in a bathroom, kitchen or living area. Maybe they would be adequate at a highway rest area! at 2/24/2009 7:18:37 AM, JRB said:Those $1.25 LED night lights are fantastic. LEDs for bicycle lights are incredible. I agree market forces should prevail. I object to CFL, particularly if forced to use them where they make no sense (they don´t last in a bathroom environment, and for many applications like garage door openers, motion detection where instant full lighting is critical for safety reasons, and places where lighting is rarely on (a closet, for example) - rather than have a law banning filament bulbs, simply taxing them (i.e. increase the cost from 25-cents to $2 each) would result in the public´s migration to non-filament use. Gradual taxation increases would allow a smooth transition without serious short-term affect upon the supply chain. at 2/24/2009 7:21:22 AM, John from UK said:We are starting to see traffic lights using LEDs. As far as I know a 150W bulb is used in conventional lights and there is the appropriate colour filter to consider. Replacing these high watt bulbs with LEDs means that even if one fails then there is no need to get a person out straightaway to change the bulb. Fewer trips to the traffic lights by a person armed with bulbs constitutes increased productivity to my way of thinking. It probably helps to keep the traffic moving more efficiently and how much time do we waste on our roads when we could be making something? Think, too, of arcades and lighted domes on shopping centres. It makes sense to me to use LED clusters to provide the light as scaffolding, etc. is not needed so often. Is there not something called the Fremont Street experience in Las Vegas? Why were incandescents replaced with LEDs? Was it only to give a better show? at 2/24/2009 9:08:33 AM, RomanB said:Lighting strategies require intelligent control and diagnostics. Light sensors are very expensive, for light pole applications, and can be reduced to having one per street and using wireless control to turn the rest of the lights on/off. Sensors can determine if there is no activity on a street and dim the lights to conserve energy. Power monitoring can measure power consumption at each light pole and charge the subdivision that is consuming the most power. Accelerometers on the poles can warn when a vehicle has hit the pole and caused a disturbance. Police can carry a small wireless keyfob to control the lights, without calling the dispatchers. This allows them to raise the lights in the event of a traffic accident. During a drug house raid, lights can be turned off for the safety of the police. Jennic has more ideas for wireless control at 2/24/2009 10:03:16 AM, KC said:This is the most absurd article I´ve seen in a long time. This says that the energy savings in the private sector mean nothing unless corporations make more money off the new technology. He´s saying that if an individual uses more efficeient light, then they will want more light. How much light can one realistically use. There are limits. Give me a break. at 2/24/2009 10:23:16 AM, J.O. said:Good Article! Here´´s what happens. Note the line "only twice the power" description (excerpts from Design News, November 17, 2008): New Year´´s Eve revelers in Times Square will have a much easier time keeping their eyes on the famous ball when it drops in the final seconds of 2008. A bigger, brighter ball was unveiled this week... ...double the size of its predecessor, the new ball has four times more surface area available for its LED lighting system and crystal cladding. “…So this ball features 11 custom-designed NEMA 3R enclosures for its 1,500-watt LED power supplies--of which there are 64 in all.” Consider that the new ball has 32,256 LEDs, more than triple the number of the old ball. Yet the new ball requires only twice the power. "We´´re getting more brightness for a given amount of power," he says, crediting the light extraction capabilities of the ball´´s optical components as well as the efficiency the Philips Luxeon Rebel LEDs. "They´´re noticeably more efficient than previous devices," he says. Burne notes that without efficiency gains made over the past year, it would have been impossible to use the building´´s existing 400 amp service without turning down the ball´´s brightness. at 2/24/2009 3:32:16 PM, John L. said:Article... interesting perspective (we will use more light if it is cheaper - light cost vs GDP).... I have yet another perspective on the same subject... The cost of electricity is only partly based on the cost of fuel...(infrastructure, distribution, etc.. are larger percentage of cost)...... So, if you use less electricity (more eff. lighting) , it will cost more per unit (assuming centralized power distribution) . Both perspectives relate to the "cost" (as in money , absolute or relative to GDP)... How does one relate $ or GDP to environment? How does one put a price on clean air?..... Any discussion of "energy efficiency" needs to address this question before any other.... otherwise, market forces ($, greed, human weakness) will trump environmental concerns every time... If you want to take matters in to your own hands, you have the option of "de-coupling" yourself from the market forces and government incentive. But don´´t expect that to save the world.. at best it will save a little piece around you. at 2/24/2009 6:51:24 PM, Rickson@ideo said:I think Tsao has a great point to make. Efficiency is not enough to change our behavior on a mass scale. We find that this happens when the focus shifts from a highly technical- and scientific-driven culture to one that creates solutions which fit and enhance the way people live. at 2/24/2009 9:50:00 PM, Professor R Rathnasamy, INDIA said:Usage in energy increase with efficient lighting system is anlogus to increased usage of Automobile system which are cheaper and some what efficient in energy conversion, in comparison to few decades back How the Enegy conversion system performed. It cannot be linked with GDP of a country at all at 2/25/2009 3:32:02 AM, Steve Nordquist said:Try that again, Ra. April 30?! This is the time I have to figure out whether C. Nutter´s lampage is better than merely kosher-style (random timer designers don´t blog) PIR lighting? Jeff Tsao has it right enough; I´m looking for good IR sources for bed & bath apps (bam! Incandescent bulbs!) and can´t help but like the notion of hyperspectral flashlamps, fixture refits over retail deadwood, and staying out of Costco. (Apologies if there´s a Costco particular to Sandia Labs.) at 2/26/2009 9:33:39 AM, Charly said:I built an ultrabright green LED into a switch on the wall of the staircase. It consumes 30mW in total (LED and Resistor) and what followed? It gives enough light to walk around safely! Without turning on the light! Why cann´t I buy such lamps for switches? Maybe no businesscase ... . I inserted a 1.5W LED lamp above our sofa for lighting the books we read: It really replaces a 25W bulb and it is very comfortable for there is light only where we need it. LED lamps are best when the direction of the light counts, and therefore LEDs are almost perfect for those purposes. Besides: I strongly recommend LED lamps to be used in seldom used areas like the garret or so for it happens again and again: After half a year you have to go there and find the light being turned on. An LED lamp would have saved more than 200 kWh! And there is no danger of a fire because of almost no heat! at 2/26/2009 9:48:17 AM, Chris Link, TI said:For those who have not met me, my name is Chris Link. I work for Texas Instruments, looking after all the Energy Technologies semiconductors enable. You are making an excellent point Margery when outlining that the real savings come from increased productivity, which for me translates to using energy smartly when switching on the lights, cooling or heating our homes and in many other areas of energy consumption. This is a great way to continue the conversation we started last week in Santa Clara, which I really enjoyed! The biggest thing that I took away from the conference last week was that the LED industry is advancing from optimizing individual components to looking at the overall lighting system. Examples: • Light with a spectral content mimicking morning sun light to help people be more alert. • Using the directional characteristics of LED-based lights in warehouses to illuminate the alleys for the forklift and not the boxes sitting at 25ft on the top shelf. • Using LEDs emitting white light called Cool White Meat giving the meat counter additional appeal. The savings through lower energy consumption and longer lifetime will definitely help because they drive adoption by the people who buy warehouses and street lights, etc. The big change is going to come from how we use light to do things. Like I said, I’m looking at all things energy related for TI, so if you’re interested in how other electronics make the world smarter, healthier, safer, greener and more fun, I welcome you to check out www.tinergy.net. at 2/26/2009 12:12:08 PM, Bill said:Where can I buy one of them there intelligent LEDs? I need one for the grand kids. at 2/26/2009 1:02:57 PM, IanP said:For generations engineers and non-engineers alike confused efficiency with cost effectiveness. I see the same happening in the article above. Quote "As lighting because (becomes?) more efficient – that is, it becomes cheaper – then lighting usage will go up". Now we as a society have thrown in a new way of confusing the issue - environmental efficiency - for all the best reasons I´m sure. The big problem with the dabate is that we refer to all three criteria haphazardly, using the same terminology to berate the customer (and the engineer) and end up making poor decisions because the real goals get lost in the gobbledegook. This sort of confusion is really is something that an engineering publication needs to avoid. at 2/26/2009 1:04:45 PM, BobGroh said:It seems to me that there is a limit to how much light energy is needed or required for a given task or given situation. Therefore I strongly suspect that providing more light energy with less electrical energy will result in less electrical energy being used. I certainly find that so in my personal life where I am changing incandescent lights to fluorescent lights as the need arises. at 2/26/2009 1:55:29 PM, MJHyatt said:Great points are made in this article. I do feel that in many areas an increase in productivity is not required. At home, if I were to install LED lights and cut my energy consumption, this results in lower energy bills for me, less wasted energy in the form of heat, wasted capacity by the energy supplier (the power plants), and saves them money as well. If streetlights are replaced with LED lamps, the benefit is to the utility, lower maintenance cost, longer life, less wasted energy and eventually lower cost to the surrounding neighborhoods – you do pay for that streetlight, at the rate of a few dollars each month, and with 50 homes paying $2 - $3 per month each, it really adds up. Hard to you believe it cost $1200 or more a month to run a street lamp for 10 to 14 hours each day! Way not make them solar powered. I would pay $3 to $4 a month for that, would you? These solutions do not require an increase in productivity to reap the benefit of lower energy consumption. It is time that we all realize that just because we are saving energy means we can increase our use of it. Just because gas is cheap does not mean we should start wasting fuel and not push for more fuel efficient cars ( and still feel or think we can drive more) or not increase our use of public transportation. The mindset of wasteful energy consumption has impacted our long term ability to be more energy independent and is costing us in many ways. It is time we look harder at how we use energy, how we can cut our energy budget and save money. These saving could go into creating jobs, further improvements in energy efficiency and eliminating waste of our resources and could (would) lead to increased productivity and of course greater profits or ROI. at 2/26/2009 4:30:34 PM, MikeW said:Interesting article, but I´m not sure I buy its premise because recommended and installed institutional and office light levels are already going down as more tasks are computerized. For residential he´s probably right - I know I like lots of light - and perhaps for industrial as well. I agree with Drdave though - LED is way over-hyped. It´s difficult to find LED fixtures that can compete even with well-designed compact fluorescent fixtures (Cree´s downlight being an exception), and linear fluorescent and higher wattage HID fixtures are much more efficient. Recently I was looking for LED to specify on a LEED project, and the fixture I initially liked turned out to have an efficiency of 10 lumens per watt - about half the efficiency of a halogen PAR lamp! You really have to watch out what you specify. at 2/26/2009 10:48:37 PM, Janez said:LED bulbs gives not enough light im compare with halogen lamps. Some better is by culd light bulbs with LED.But much apends from number of used discrete LEDs. at 2/28/2009 12:22:41 PM, Bob said:"... and can interact with their environments and humans in ways that make both of them more productive and intelligent..." Yeah right, LEDs will make humans more intelligent...? You should buy a few boxes, but right away lady...Dr Somogyi Károlya műszaki tudomány kandidátusaalternatív E-mail cím:mfaoutcast@freemail.hu

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