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Parking deck before LED lighting was installed - images courtesy WRAL

Parking deck after LED lights were installed
Raleigh looks to LEDs to cut its power bill and provide brighter lighting

In an effort to cut costs and become more environmentally friendly, the city of Raleigh, NC is looking to LED lighting. The city started a pilot LED lighting program last year in a downtown parking deck. As a result, a 40% reduction in power has been recorded as well as substantial increases in light output, according to Progress Energy.

WRAL, the first HDTV station in the U.S., reports that Raleigh now wants to expand from simply providing LED lighting on a single floor of a parking deck to lighting the entire city with LEDs. The program will eventually expand to use LEDs for street lights, architectural/accent lighting and pedestrian walkways.

LEDs will be provided by Cree, Inc., an RTP-based lighting company. Cree specializes in LED lighting/backlighting used in digital camera flashes, automotive dashboards, traffic signals, street lamps and various other applications.

The upfront costs for providing LED lighting throughout the entire city will be markedly higher than traditional lighting. However, Mayor Charles Meeker notes that the costs could be quickly recovered due to the power savings afforded by LED technology. Meeker says that Raleigh could save roughly $80,000 USD a year in utility bills just by switching its parking decks from traditional lighting to LED lighting. Meeker also believes that significant reductions can be made in the $4 million USD that the city spends to power street lights each year.

"We are thinking by our role of testing these products, implementing those products and then publicizing the successful tests, we can help not just our community, but communities throughout the country to a better job with energy conservation," said Meeker.

"The use of LED lighting will assist in addressing our nation's energy challenges and helping Raleigh and other cities develop energy-efficient infrastructure in the future," said Greg Merritt, a spokesman for Cree.

LEDs are quickly finding a home in a number of varying arenas. Companies like Asus, Fujitsu and Sony have introduced notebooks which use LED backlighting for brighter, sharper screens and reduced power draw. Also, car manufacturers like Toyota and Volkswagen are using LEDs for headlights in their high-end automobiles.

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LED's
By digital batman on 2/14/2007 12:33:48 PM , Rating: 3
I work for the company mentioned in the article (Cree) and one of the biggest hurdles we are experiencing with the adoption of LEDs as standard lights is the cost. Fortunately, LEDs last SO much longer than incandescents or flourescents (I think LEDs are on the measure of 60,000 hours) that the replacement timeframe will allow us to have much cheaper alternatives down the road. As with any technology, the initial cost to early adopters is high but the benefit of longevity ends up outweighing the initial install costs. And the previously stated "costs like 45 cents" is accurate. For the same light as an incandescent, the cost savings is amazing. Plus when one LED goes out on a fixture, all the other ones are still on.




RE: LED's
By fic2 on 2/14/2007 12:46:45 PM , Rating: 2
Could you tell us what the initial cost for one of these garage lights is? I live in a loft building and we are about to replace all of our garage lighting and I would like to have our HOA look at LED. I have already convinced them to go the LED replacement route for the exit signs. Our ROI on that is something like 12 months.


RE: LED's
By digital batman on 2/14/2007 4:09:08 PM , Rating: 2
I don't work in the packaging aspect of the business. I maintain the machines that make them...so I have no idea what a fixture would cost....


RE: LED's
By digital batman on 2/14/2007 5:00:53 PM , Rating: 2
And Cree makes the LEDs, someone else makes the fixtures and basically uses our "parts".


RE: LED's
By patentman on 2/15/2007 6:47:20 PM , Rating: 2
Just an idea of cost. I've seen LED bulbs ranging from $30-$80 a pop, but these are for home use.

http://www.thinkgeek.com/clearance/7aa8/


RE: LED's
By hubajube on 2/28/2007 1:55:30 PM , Rating: 2
I would like to replace the bulbs in my ceiling fans with LED's. Does anyone know where I can get those kinds of bulbs?


RE: LED's
By masher2 (blog) on 2/14/2007 2:12:07 PM , Rating: 3
> "the previously stated "costs like 45 cents" is accurate..."

All the figures I've seen on LED lighting indicate the efficiency is on par with that of fluorescent, and much worse than sodium lamps. A typical fluorescent bulb runs 60-100 lumens/watt, whereas sodium lamps can be double that.

White LEDs available today top out at only ~75 luments/watt (though some lab prototypes are considerably above that. So I'm guessing the 'cost savings' here are due primarily to reduced bulb costs more than any electricity savings.


RE: LED's
By Cogman on 2/14/2007 3:23:55 PM , Rating: 2
A few things about LEDs make them much more promising then Fluorescent bulbs. As I recall, they have a theoretical maximum efficiency of %100. Now that just blows anything that a Fluorescent bulb can do (They are like %30 or so, and incandescent is like %10, if I remember correctly). They also cause less eyes strain then a fluorescent bulb will. I hate to be in a room with fluorescent lighting for too long.

Another bonus to the bulbs is that they don't just burn out (again, I may be wrong here) but instead they gradually decay. That is much better for the consumer (I may be mixing them up with OLEDS).

Anyways, just thought those points should be mentioned.


RE: LED's
By masher2 (blog) on 2/14/2007 3:35:55 PM , Rating: 2
> "A few things about LEDs make them much more promising then Fluorescent bulbs..."

Long-term promise, sure. I certainly agree. I'm simply pointing out that current LED lighting solutions are not more energy-efficiency than a good fluorescent, and much less efficient than the sodium lights most municipalities use for street lighting.

> "They also cause less eyes strain then a fluorescent bulb will..."

There are flickerless fluorescent bulbs, though as they're more expensive, they're not as widely used.

> "Another bonus to the bulbs is that they don't just burn out..."

They can do so, though this is much rarer than for other lighting solutions.


RE: LED's
By digital batman on 2/14/2007 4:14:14 PM , Rating: 2
And as I hinted at before, when an LED in an LED fixture dies (tens years from now), the fixture still works (albeit with one less light). When a flourescent fixture (or halogen or sodium for that matter) dies, the fixture no longer produces any light.


RE: LED's
By masher2 (blog) on 2/14/2007 4:19:21 PM , Rating: 2
Actually, most commercial fluorescent fixtures contain multiple bulbs, so when a single bulb dies, the fixture still produces light.

No one is arguing the greater longevity of led lighting, nor its future promise. However, the current level of technology has indeed been somewhat overstated.


RE: LED's
By ZmaxDP on 2/14/2007 4:18:13 PM , Rating: 3
Just to contradict some things said here. I worked in an architectural materials library and lab for three years(up until about 6 months ago when I got a "real" job.) One of our focuses was architectural lighting technologies. For starters, the LED lamps we had in our lab were about 10 times more efficient than the CFL lamps we had, and those are about 10 times more efficient than the common incandescent lamps. We had almost every conceivable lamp hooked up to individual watt meters and monitored them over the course of a year. These were all "current" technology. So trust me, LEDs are more efficient currently. I don't know where you got your figures from, but someone was fudging the numbers somehow I think.

Also, there is no such thing as a "flickerless" flourescent bulb. There are "flickerless" flourescent fixtures. What makes a flourescent (or any gas reaction bulb - like sodium lighting) flicker is the frequency of the electrical current running through the gas. Old flourescent fixtures had ballasts that changed the frequency to something noticeable, hence the "flickering." It's basically like taking an old CRT monitor and changing it's frequency to 50 Hertz. You'll see it. Old flourescents hit 60 Hertz I believe, but that's going off memory and I'm not vouching for accuracy on that one. Modern flourescents are usually double or triple that figure so that we can't "perceive" the flickering, though it is still occurring. (Just FYI). You can put a fancy new flourescent bulb in an old fixture and it will flicker like it's 1969. Put an old bulb in a new fixture and you'll see no evil - though it will still be there.

Some of the eye strain from flourescents is also in the color of the light (vs. daylight, etc...). The other is from the flicker. If your bulbs don't flicker, then it's color that's the problem. LED's aren't perfect, but color wise they're much closer to sunlight than older flourescent bulbs. (You can also buy "natural" flourescents now that have a film to convert the natural output of flourescent to something nicer - basically a photography filter around the tube.) I would mention that there are two kinds of LED bulbs on the market. There are "monochromatic" bulbs which use white LED's the generate white light (which lack much of the spectrum) and there are tri-color LED's which replicate sunlight much better (even than incandescent bulbs) These are less efficient than the monochromatic ones, but not much. They are also more expensive though, and since both increase, that might be an issue.

Still, if you can afford the initial investment, they will save you money two ways. They are more efficient than any other light source we currently have (even sodium lights - we had one of those plugged in to, and yes we adjusted the figures for light output. We measured lumens at three distances and used this distribution to do performance/watt on each lamp. I only wish we'd checked output more often as I can't say much on how output degraded over time. We didn't own the light meters, only borrowed them a few times over the year.

Hope I cleared a few things up. If you've got conflicting figures that you've measured, or a report somewhere, I'd love to see them because I want to know how they got their results. I at least know how I got mine.

Adios!


RE: LED's
By masher2 (blog) on 2/14/2007 4:33:28 PM , Rating: 4
> "I'd love to see them because I want to know how they got their results. I at least know how I got mine..."

My figures come straight from Cree's website, the provider of these fixtures. They quote a 78 lumen output from a 500mA led, driven @ 3.5V. The math on that works out to 44 lumens/watt, or less than half what you get from the best fluorescent bulbs. I've seen research papers on LEDs that can do 150 lumens/watt...but those are not commercially available. And even those are less efficient than sodium lighting.

> " We had almost every conceivable lamp hooked up to individual watt meters..."

Ah, but to measure luminous efficacy, you need both a wattmeter and a specially-calibrated lightmeter. Did you have both?

> "there is no such thing as a "flickerless" flourescent bulb. There are "flickerless" flourescent fixtures."

True, but the end result is the same. And, since more and more fluorescent bulbs incorporate the ballast and fixture with the bulb, the distinction here is rather sterile.

> "LED's aren't perfect, but color wise they're much closer to sunlight than older flourescent bulbs..."

Untrue. Fluorescent bulbs are sold in a wide range of color temperatures. Furthermore (as I've already explained in another post) common white LEDs don't actually have a color spectrum at all...they produce two (for the cheapest variety) monochromatic light sources, which the eye perceives as white, even though the reality is quite different.


RE: LED's
By digital batman on 2/14/2007 4:54:33 PM , Rating: 2
And drawing from information on Cree's site, there are several "powers" of lighting. For instance, there is a company LED Lighting Fixtures here in RTP that is producing a fixture using our LEDs that produces 650 lumens with a 10-12 watt input. I am not being confrontational here, but is there another similar output from a different type of fixture (asking because I don't know)? And for the most part in all of our posts so far, we have been comparing one light for one light. The number of LEDs that would be used in the place of a similar commercial application of flourescents or sodium lights would produce a much larger total light using less power and occupying the same amount of space. I wish everyone could come to Cree and browse the demo room. You would be impressed with the amount of light LEDs in the same space as a 4' flourescent put out.


RE: LED's
By masher2 (blog) on 2/14/2007 5:24:30 PM , Rating: 2
> "For instance, there is a company LED Lighting Fixtures...using our LEDs that produces 650 lumens with a 10-12 watt input..."

Which works out to ~60 lumens/watt. Again, below that of fluorescent, and far below sodium lighting.

> "I wish everyone could come to Cree and browse the demo room. You would be impressed ..."

Figures don't lie. LED lighting certainly is more compact and long-lasting than other approaches. But its not the most energy-efficient choice...not yet, at least.


RE: LED's
By lemonadesoda on 2/14/2007 8:42:18 PM , Rating: 2
A designed-for-purpose fluorescent lighting circuit would have a voltage frequency doubler at the SOURCE... ie. no need for expensive converters in EACH light fitting. Just a regular wired fitting, now receiving 100hz or 120hz (depending on country). That reduces flicker considerably.

This is becoming more and more common in libraries where most of the lighting is fluorescent. When I was in college I couldnt work in the library... I have eyes very sensitive to flicker. (A quite common problem)


RE: LED's
By FredEx on 2/15/2007 12:52:31 AM , Rating: 2
I've recently read where the measuring of lumens output when it comes to LEDs can be extremely misleading. The reason is that lumens measurements are made at several points around a bulb and averaged and an LEDs most powerful output is out forward at a somewhat narrow angle. That is why an LED fixture may have the outer LEDs angled outward to spread the light or they use some sort of diffuser to spread the light. Take any other lighting source mentioned and measure its output at only one point, similar to the point of an LEDs maximum brightness, and you will get a measurement far less than the LED source.



RE: LED's
By mindless1 on 2/14/2007 3:40:46 PM , Rating: 2
You don't remember correctly, LEDs actually being used are less efficient than fluorescents actually being used. If we want to talk theory, in theory if we go without lights for long enough our eyes will become accustomed to the dark via evolution. Let's ignore theory and focus on what's available to use now, or even more specifically, what's not just available but at reasonable price-points, there are really expensive LED lights and then there are obscenely expensive LED lights.