LEDs for lighting: Efficiency is not enough

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Lighting represents as much as 25 percent of your home's electrical use, so it is a significant part of your monthly utility bill. Lighting affects the way you feel, work, and interact with others. It helps you accomplish everyday tasks. How would you manage without the light you use to read your paper, the desk lamp your children use when doing their homework, or the lighting you use to prepare your favorite meals. Light gives us beauty as well as vision, and the quality is often far more important to us than the quantity. Efficient lighting is a science as well as an art. And yet, most of us still use the incandescent bulb, which is basically the same technology invented by Thomas Edison over 100 years ago. Since lighting represents as much as 25 percent of your home's electrical use, increasing your lighting efficiency is one of the easiest and fastest ways to lower your energy bills. One easy way to reduce your electric bill without sacrificing the quality of your home lighting is to replace your incandescent light bulbs with compact fluorescent lights. Compact fluorescents come in a variety of sizes, shapes, and wattages to fit most lamps and light fixtures. The light they provide is a soft, warm color, similar to incandescents, but they use up to 75% less energy, and should last approximately 10,000 hours. That is about ten times longer than a regular incandescent light bulb. The original compact fluorescents, introduced quite some time ago, had some drawbacks. But those shortcomings have largely disappeared, and newer compact fluorescents are very easy to live with. When you purchase your first compact fluorescent bulb, you may experience price shock, but don't let that scare you away. It's true that these lights are more expensive than incandescent bulbs, but they will last ten times longer! The best place to use compact fluorescents is where the lights burn an average of an hour or more a day. Exterior lighting is one of the best places to make use of energy efficient lights because of their long hours of use. You can get everything from low voltage lights to line your walkways and patio to lights that are solar-powered and convert sunlight directly into electricity, adding nothing to your utility bill! The invention of incandescent light bulbs was an incredible event, but considering what you spend each year to light your home and yard, it is fortunate that you have more choices now.

170 Lumens per watt has been demonstrated. Thats twice as good as cfl and no mercury. 50,000 hour life is at 80C. At 40C life is well in excess of 100,000 hours. Much more rugged and starts are not an issue. Much smaller than a cfl. So why are you clinging to old technology?

This has been a fascinating discussion. What has only been hinted at is the core of our culture (now rapidly dissipating): the free market. Whether for home use or municipal street lighting or commercial lighting, the free choices of individuals looking after their own interests will produce the long term best results. The CFL mandate is the perfect statist solution in contrast. How many here will dispute the inevitable disaster of toxic landfill reclamation where the state will necessarily have to undo their own edicts at our expense. On a personal note, I am installing outdoor LED ambience lights along a deck. Looking inside the fixture, I found six LEDs and a small transformer...wait for it...for $400 net. Probably won''t recover the first costs, but it will be efficient. And it was a free choice -- not mandated by the gummint.

Smarter lighting allows better control of consumption. Current Mercury polluting CCFLs are horrible for dimming and slow to warm up to full brightness. People often get too much lumen capacity to compensate for the slow warm up. Then once lights reach full output the lumen level is higher than really needed. LEDs are dimmable over a wider range and can reach full brightness instantly. This allows for better user control for minimum consumption. My kids don''t adjust their lumen consumption based on any awareness of cost! It is like cigarettes, higher cost does NOT much alter consumption. There is a minimum level of need, and there is a comfortable level of need. Would I pay more attention to shutting off unneeded lights if price was double? Yes, but not that much more than I already do. Who funded this research? Sounds like there was an agenda behind it.

"... 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...

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.

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.

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.

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.

Where can I buy one of them there intelligent LEDs? I need one for the grand kids.

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

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.

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.

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.

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.

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

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?

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.

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!

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 ;)

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....

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.

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.

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.

Excuse my error...I meant does LED really run much more efficient than discharge lamps....I doubt it.

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?

Does LED is really much more efficient than discharge lamps? I doubt it...

how dumb can you be??

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.

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.

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.