Comments on: City tries to cut energy bills with LEDs

Raleigh, N.C., is conducting a trial to see if LEDs live up to their reputation of a cheaper, more efficient light source.
Photos: LEDs light the way in Raleigh

[punterjoe]

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?

[scottthesculptor]

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

[afterhours]

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?

[treads0322]

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

[Sparky672]

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

[lnxpro]

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.

[DougDbug]

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.

[airwalkery2k]

LEDS=Bombs

I hope the City of Boston doesn't implement measures like this. There will be bomb scares all over the place.

[gggg sssss]

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?

[spothannah]

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.

[m.o.t.u.]

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.