My recent experience with LEDs

[struggle4progress]

inspired by this LBN thread:
GE announces new LED bulb will last for 17 years
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=102x4341845#4341944

I like diffuse indirect lighting and aim for multiple light sources in rooms. As the evening progresses, I prefer a dimmer house. My lighting is varied: mostly a mixture of low wattage incandescent and CFLs, with some tube fluorescent, as well as some higher wattage incandescent in seldom-used fixtures. Fluorescents dominate my living space.

Recently, I've been exploring LEDs. I have some rope lights in several more casual rooms; I think they add nicely to overall lighting but probably won't be to everyone's taste. In general, the cheaper bulbs are dim and often bluish; the brighter bulbs are heavy (due to heat fins), oddly shaped, hot to the touch, curiously unidirectional, and expensive. I bought one 11W LED but wouldn't be in a hurry to buy another: it cost about $50; the light is nice white and bright, but the clunker has a heavy metal heatsink on it and the light is very unidirectional; it might be a good spotlight but I don't need spots. I wouldn't buy a one watt edison base LED: it would be too dim to be useful. A single three watt LED will provide enough light to easily find your way into a room and back out, if you're picking up something in plain sight; the light will be rather dim and probably slightly bluish. I replaced a CFL in an always-on outdoor lamp with one of these: the light is entirely adequate there and electricity savings ought to pay for the bulb twice over in the expected five year continuous-use lifetime. Five or six 3W LEDs give me enough light to work comfortably in a room for an extended period, if they're in appropriate fixtures (translucent shade or reflective white interior with no frontal obstruction); if I light one room well and leave one of these 3W burning in every nearby room, I can use the house routinely at night without flipping switches constantly while drawing less than 20W. I think I'll spring for some more lighting fixtures to see how a room works with eight or nine 3W LEDs

Pricing isn't settled. You can pick up 3W LEDs in the $6-$10 range online; sometimes that includes shipping, sometimes not; and there are enough places that will try to get you to shell out $20-$30 for a 3W bulb, which is just laughable for something that gives the illumination of a 20W incandescent

The economics is iffy still. I can pick up good white CFLs equivalent to 40W or 60W incandescents for about $1 each if I buy larger packages while two or three bluish 3W LEDs providing the same illumination will set me back $20-30. Compared to the CFL, you might save 50% on the wattage, and the LEDs allegedly aren't degraded as quickly by turning them on and off; but at $0.08/kwh the savings won't add up quickly: in continuous use, over 50000 hr (a five or six year period), three 3W LEDs cost $36 to run while a 20W CFL costs $80, so the savings is perhaps ($1 + $80) - ($25 + $36) = $20. Much may also depend on personal habit: if you're good at flipping switches when you leave rooms, there's little upside to leaving a dim bulb burning in a room you're not using: if you're bad at it, there may be some savings here. In the hot Southern summer, I try to keep lights off, and having some bulbs that adequately light a room without any noticeable heat may keep me from closing up and running the AC

[Turbineguy]

1. My outdoor lighting consumption

went from 440 watts to 24 watts from incandescent to LED's

[Warpy]

2. Spotlights are fine in torchiere fixtures

with the light aimed up at a white ceiling. They provide pretty good ambient light.

My own place is heavy on the CFL lights. I confine LEDs to my headlamps for rummaging in closets and fixing puters. They're going to need more work to be decent as environmental or task lighting.

[NoNothing]

3. I think you might be getting some figures mixed up

A 20 watt CFL should be bright like a 100-watt incandescent bulb. Way, way, way, brighter than 3 3W LED bulbs. Maybe you're thinking of a 20-watt-equivalent CFL, which should only actually draw a couple of watts. If you compare watts per lumen, CFLs will almost always beat any reasonably priced LED bulbs on the market at any light-bulb-level of lighting. A 40-watt-equivalent CFL should only draw around 9 watts.

[struggle4progress]

5. Yeah, the package claims 75W equivalent, which is something like

four 3W LEDs; as a quick and dirty visual guess, the 11W LED gives about as much light. None of this is terribly accurate, since one is comparing apples to oranges: watts aren't convertible to lumens. If the 20W CFL is four 3W LEDs, maybe the five year savings is in the $10-12 dollar range or maybe it's a wash. I'd guess the dim LEDs are somewhat more energy efficient: there's absolutely no detectable warmth from the 3W bulbs, while the 11W LED is uncomfortably warm to the touch and either a 15W or 20W CFL gets too hot to handle

Close enough for government work, I say. There's no point in doing fastidiously accurate calculations with all the unknowns

[NoNothing]

7. You're right watts aren't comparable to lumens

It's just that a newish 20-watt CFL bulb gives over 1000 lumen. I'm skeptical that a 3 watt LED bulb emits over 250 lumen, let alone omnidirectionally. The 3-watt LED bulbs I see are usually around 100 lumen max, making 4 of them closer to a 7-watt CFL in actual light output.

EDIT: Bottom line is you almost always use less electricity with CFL than with LED for the same amount of light, contrary to popular belief.

[struggle4progress]

14. Websearch suggests claims run from 150 to 400 lumens for 3w 120v bulbs

For the ones I've tried, I might guesstimate 200-250 lumens, based on not-terribly-scientific visual comparison with other lighting sources: four of my 3w bulbs will do me for working in a room after dark, though I might be slightly happier with five bulbs.

I don't know for sure, but it's my impression you're wrong about conversion efficiency, though there has been some ongoing debate about total efficiency comparisons between LEDs and CFLs when taking into account manufacturing energy:

August 4, 2009, 12:01 AM
LEDs Are As Energy Efficient as Compact Fluorescents
By ERIC A. TAUB
While there’s no question that LED lamps use a fraction of the energy to produce the same amount of light compared with a standard incandescent bulb, several Bits readers have pointed out that that’s only half the story. If the energy used to create and dispose of the LED lamp is more than that for a comparable standard bulb, then all of the proclaimed energy savings to produce light are for naught. Until recently, no one knew if that was the case. In March, a preliminary study reported by Carnegie Mellon indicated that LED lamps were more energy efficient throughout their life, but the researchers pointed out that not every aspect of the production process was taken into account. A new study released on Tuesday by Osram, the German lighting giant, claims to have confirmed the efficiency findings ... http://bits.blogs.nytimes.com/2009/08/04/leds-as-energy-efficient-as-compact-fluorescents/

[tinrobot]

4. I just replaced a bunch of LEDs

I bought them about three years ago for the overhead cans in the kitchen. They were expensive and promised 40w worth of lumens. After bringing them home, they turned out to be more like 25w bulbs, and after 3 years, they were dim enough to be worthless.

Maybe LED technology is better now, but they definitely left a bad impression on me.

[struggle4progress]

6. The illumination claims are all over the place and frequently dishonest, I think

[HillbillyBob]

11. Yes the claims are all over the place

I found that if i look for reviews on separate sites, not the site selling them that you get a better idea.

I have been buying pairs of 3.5 watts that equal about 40 wats for 15$ a pair at Sams club, their 3.5 outdoor floods equal about 45 watts worth of light and the more recent ones seem brighter white and less blue. I remade the dining room 5 bulb fixture to shine on the ceiling instead of on the table. I put 5 3.5 watts in it. We get a nice bright 200 watts worth of light(i forget lumens off hand) for 17 watts. I know they are unidirectional, but reflected off the white ceiling it fills the room with light. The outside floods to not make the back yard look like a ball park and we live out in the country and I don't want to be putting out a lot of light pollution so that we can see the milky way..unfortunately our neighbors insisted on turning back on the street light that I had shut down when i moved here. 400watt thing that is such a waste of power and we live 8 miles from town and every freaking house along the road has to have at least one of those its a lot of coal power wasted if you ask me.

http://www.ledlight.com/side-firing-led-light.aspx
I bought a couple of these and put one in the range hood over the stove(its in a closed fixture so it wont get greasy and one in the bathroom over the sink. I want to add some more so I have some that shine out into the room and couple that shine down. Between the two types they fill the room with light and the white is a color that if you are a lady putting on make up it will be closer to day light than most anything. They use 4 watts and give 250 lumens about 50 -60 watts worth. They also carry tube lights to replace fluoro tubes 2 and 4 ft one is 1950 lumens I plan to get some of those as i can afford them they use 19 watts compared to 40 per tube in my kitchen and in the green house for plants.

[struggle4progress]

16. I had been wondering about those side-firing ones, but they seemed a bit pricey for my tastes

[dhpgetsit]

8. A couple nice features of LED lighting.

Unlike CFLs they can have dimmers
They are long-lasting and efficient.
There are environmental and safety advantages too.

I have this idea of using them in the hallway randomly placed overhead to resemble stars, and with sensors to come on if it is dark and movement is detected. :)

[Ready4Change]

9. Like that stars idea. /

[nosmokes]

10. you can always use fiber optic for the stars.

[NYC_SKP]

12. LEDs are a proven technology, but the residential market is still in it's infancy.

I'm glad you're experimenting, but the prices are still high and the offerings of LED products to replace CFLs are very limited.

There's no doubt in my mind that LEDs will become more widely available and their prices will fall.

I've got several I've been using in prototypes, particularly expensive but powerful high-brightness LED arrays.

My latest two are very bright 3400 lumen warm white and 5000 lumen cool white arrays, 24V 2amp units.

I haven't built fixtures yet for these but I have for other less powerful units and have them around the house and in the shop.

These require heat sinks but are just remarkably bright and, in my experience with them, very durable and reliable, unlike CFLs.

When one considers that they might last 4-10 times as long as a fluorescent lamp, calculate the costs of production between one of these and several of those, it's easy to see that they're far more environmentally friendly than anything else on the market, even at their current high prices which will be dropping considerably over time.

The light emitting part is less than 1 mm thick:



:hi:

[unabelladonna]

13. do they fit in regular fixtures?

or do i have to replace all my lamps and chandeliers? also do they give off a warm light(rather than the bluish/white lights which are in regular fluorescents)? thanks for the info. i think i'll go straight to the LEDs..i can't stand fluorescent light (very unflattering PLUS they hurt my eyes).

[struggle4progress]

15. It depends on what you get. You can buy edison base E26 or E27 bulbs,

but the bigger and brighter ones tend to be oddly shaped with heat fins to limit heat degradation of the LEDs -- so they're rather heavy and may not fit conveniently in every fixture, despite having a standard edison base. And the bigger brighter ones are really too expensive for my tastes -- I mean, $50 for a light bulb? C'mon: I could buy a comparable CFL for $1; it might use one and a half or two times as much electricity for the light, but if I drop it and break it, I'm out $1, not $50

I'm currently playing with 3W standard edison base LEDs: the price per bulb is comparable to early CFLs but they are much dimmer and the light is slightly bluish. They look like ordinary bulbs but the globe is plastic, not glass. They'll fit OK in standard fixtures, but the ones I have I'd estimate to be equivalent to maybe a 20W or 25W incandescent in total light output. So if you replace (say) a 15W CFL with one of these, the room will seem dark. On the other hand, if you use five of them in fixtures that really let the light out, you may find it's totally satisfactory, depending on your color tastes. I just compared a 3W CFL to a 3W LED in a room in my house; the LED was definitely brighter before the CFL warmed up, but when the CFL got up to steam, I found the color difference annoying and thought I might prefer the CFL alone; the bluish LED and the slightly yellowish white CFL didn't play well together at that illumination level. With enough fixtures and enough LED bulbs, on the other hand, the bluish tint doesn't bother me: I've lit my home office at night for the last month with four 3W LEDs, though five or six might have done better. You can get whiter ones than I bought, but they give off slightly less light. I haven't tried any with a standard candelabra base, though they're available. My advice would be not to rush out and commit to anything yet: if you're interested, buy a handful and play around with them. I think I know how to incorporate some of them into my house, but because they're so dim I'll end up buying some additional (standard) fixtures to use them