February 12, 2007 8:01 AM PST

City tries to cut energy bills with LEDs

Raleigh, N.C., wants to become LED City.

The city, which is in the center of the state's tech hub, is conducting experiments to see if it can cut energy consumption and maintenance costs by replacing conventional public light fixtures with ones based around light-emitting diodes.

In December, Raleigh--in conjunction with LED manufacturer Cree--replaced high-pressure sodium lights in a downtown parking garage with LED lights. Although the LED lamps cost substantially more than regular sodium lamps, they require less electricity and need to be replaced far less often.

Early projections indicate that the expense of retrofitting the garage's lighting system will get recovered in cost savings in two to three years, said Mayor Charles Meeker.

"We are saving over 40 percent of the energy we would otherwise use," said Meeker, who's currently on his third two-year term. "And the quality is better. With sodium lights, you get bugs in the cover, and the light is kind of yellowish."

Parking lot with LEDs

Next, Raleigh will kick off a pilot program with LED streetlights and will also seek funds to convert the city's other parking garages. If all seven municipal parking lots in the city were retrofitted, it could save the city $100,000 a year in energy consumption and decreased maintenance, he said. The lights in stadiums, gyms, schools, parks and other public venues could be next.

If successful, the experiment could ultimately serve as a showcase for something several LED manufacturers are angling to accomplish: maneuvering LEDs into the commercial and residential lighting market. LEDs are used in flashlights and car headlights and taillights, but commercial and residential lighting represents a much larger opportunity. Approximately 22 percent of the electricity consumed in the United States goes toward lighting, according to the U.S. Department of Energy.

LEDs can last 75,000 hours or longer and consume far less power than standard incandescent bulbs. Only about 5 percent of the energy that goes into conventional bulbs actually turns into light; the rest gets dissipated as heat. If 25 percent of the lightbulbs in the United States were converted to LEDs putting out 150 lumens (a measure of light output) per watt--higher than the most current models--the country as a whole could save $115 billion in utility costs cumulatively by 2025, according to University of California Santa Barbara professor Stephen DenBaars.

LEDs also have begun to outperform fluorescent bulbs in energy efficiency, said Cree CEO Chuck Swoboda. The company last year unveiled an LED that can put out about 70 lumens per watt. That's a bit better than many compact fluorescent bulbs--those cone-shaped things that fit into regular light fixtures--on the market, which often get 60 lumens per watt.

The problem up until now has been cost. Consumers and businesses can buy lighting fixtures based around LEDs now, but the price is high compared with other types of lights. While fluorescent manufacturers dispute many of the energy efficiency claims by the LED industry, they also note that their products cost far less.

The rising cost of electricity, combined with the declining prices of LEDs, however, is making diodes more attractive to manufacturers of lighting fixtures, Swoboda said. Over the next year, LED-based light fixtures for commercial buildings and signs will begin to increase in number, he said. The commercial market in many ways is inherently more attractive because they don't need to be replaced as often, which cuts down the number of times the maintenance crew has to put up a ladder.

"When you get into lights that are on 24-7, the maintenance costs certainly go up. LEDs are going to find their ways quicker there than other markets," Swoboda said. "The home is not typically mission critical."

Nonetheless, he added that LED lights would likely begin to appear in new homes in six months to a year. Contractors can absorb the cost in the overall price of the home.

Making an LED light fixture stronger or less bright is largely a matter of how the fixture is designed and the number of LEDs inside. A lawn light based around LEDs might have two of the diodes inside, said Swoboda; a light for a garage might have 84.

LEDs emit red, blue or green light on their own. To make white light, the light from blue LEDs passes through a yellowish phosphor.

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11 comments

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LEDs vs CFs ?
OK, Compact Flourescents still hold a significant up-front cost advantage, efficiency seems close enough to be out of contention. How about the AFTER life cycle? CFs contain some heavy metals that make proper disposal an issue. What's the disposal/recycling situation with LED lighting?
Posted by punterjoe (163 comments )
Reply Link Flag
LEDs vs CFs
Just total volume of waste material for one.
Also the volume of phospor atop the bluish LED in a "white LED" is quite small in comparison to the phosphors lining the glass tube of the CFs.
CFs require high freq converters in their bases so there's additional metals and insulators.
You could say that LEDs require DC so the have their own associated additional waste - but many applications use the power supply to ower many LED fixtures.
The phosphors are much more toxic than the LED itself. Hoefully some materials engineer will stun the world with a true white LED or the mixed RGB LED white sets will end up cheaper than adding the phosphors
Posted by scottthesculptor (91 comments )
Reply Link Flag
mercury
it's the mercury in a CF that's the problem. They qualify here in
Raleigh as toxic waste, and have to be handled at a special
dump, not the normal trash.

Also, I've been using CFs throughout my home for almost 4
years. The bulbs last about half of the longevity claimed by the
manufacturers. They (CF) bulbs certainly save money, but they
don't give the economics the packaging claims. The big thing I
like is that they don't produce near the heat in the summer.
Expect 3-4 years, not 5-7. If you read the packaging, they are
expected to be used only about 4 hrs a day, too.

The LED market could be huge, but there's issues in it, too. We
have tried a number of the LED replacements for our truck --
and haven't yet found a set that work for the combo parking/
brake light in a Ford F350. Blinker circuitry doesn't like the little
beasties. Household lighting is a lot simplier than vehicles (save
perhaps the dimmers), so maybe they'd do well in most
circumstances. CFs aren't recommended for bathrooms or
places like above the stove or in appliances like the frig or oven.
Might be great places for LEDs. Time to buy Cree stock?
Posted by afterhours (215 comments )
Link Flag
apples to oranges?
"...Only about 5 percent of the energy that goes into conventional bulbs actually turns into light; the rest gets dissipated as heat...LEDs [put] out 150 lumens (a measure of light output) per watt..."

These statistics would be much more effective if some direct comparisons were made between the two technologies - tell us how much energy consumed by LEDs is used to produce light, or how many lumens a conventional light produces per watt. Maybe this isn't a journal paper, but CNet does have a fairly technical audience and I imagine this is the sort of thing we'd all prefer to see in an article.

-Mark
Posted by treads0322 (3 comments )
Reply Link Flag
does this help?
LEDs convert 15 to 25% of the consumed energy into light and
75 to 85% into heat. Incandescent: approximately 5% light and
95% heat

Approximate Lumens per Watt-

Wax Candle: 0.3
Incandescent: 10 to 20
Halogen: 15 to 25
CF: 45 to 60
Fluorescent Tubes: up to 100
LEDs: up to 70 (30 - 45 more typical)
prototype white LED: 150 claimed
Posted by Sparky672 (244 comments )
Link Flag
do the math...
take for instance a 100 watt conventional light bulb.

uses 100 watts and produces about 1500 lumens.

an LED outputs 150 lumens per watt. so that means that 1500 lumens of a standard conventional bulb, divided by 150 lumens of an LED per watt = 10 watts.

that means that an LED would use 10 wats to produce the same amount of light as a conventional light bulb which uses 100 watts.

makes it 90% more energy eficcient and life expectancy of an LED is what. 400,000 hours or something like that. a conventional bulb has a life expectancy of about 2000 hours if i remember correctly. and that's if it's being used 4 hours a day only. an LED can stay on 24/7/365 and doesn;t burn until they claim that it's life expectancy expires.
Posted by lnxpro (28 comments )
Link Flag
Contractors can absorb the cost ...
>>>> Contractors can absorb the cost in the overall price of the home.

HA HA! HA! HA! There's nothing a contractor likes more than "absorbing costs"!

I'm sure the developer is willing to ADD the cost to the price, with a "small" mark-up.

If the buyer can finance the cost of the lights over 30 years along with the cost of the house, that makes sense. The combined house-payment and utilities should be less with the LED fixtures.
Posted by DougDbug (62 comments )
Reply Link Flag
LEDS=Bombs
I hope the City of Boston doesn't implement measures like this. There will be bomb scares all over the place.
Posted by airwalkery2k (117 comments )
Reply Link Flag
China holds teh clue
Problem is that both CF and LEDs are / will be made mainly in China. So the entire investment in manufacturing, and resulting profits will accrue to the guys who are working on how to shoot down (our) satellites. A great opportunity to invest here, deal with labor costs realistically ( maybe Wal-Mart could get into the business) rather than exporting yet another technology base wholesale. Of course, the Kyoto wingnuts want to ignore the inconvenient truth that not only will we pay the Chinese to manufacture this stuff, we will also export "tonnes" of money in carbon credits for the pleasure. Where is Edison when you need him?
Posted by gggg sssss (2285 comments )
Reply Link Flag
LEDs from China
It they make and sell us LEDs then they need us as much as we need them. No us, no sales, no jobs, idle factories, and (their big fear) unhappy masses. Welcome to the small/interdependent world.
Posted by spothannah (145 comments )
Link Flag
This is a tough one.....
realizing that a country so recently Communist is now a perceived threat on so many levels. Good on Raleigh for trying to move forward on lighting, the Chinese are constructing an entire city based on Green Principles, looks like they got the jump on you again. Another inconvenient thruth is Edison is in fact long dead, so maybe a different solution will be required. Wishing you all the best for the future.
Posted by m.o.t.u. (96 comments )
Link Flag
 

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