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LED Lighting & Energy Efficiency

Discussion in 'Energy, Environment, and Policy' started by vfx, Nov 5, 2008.

  1. vfx

    vfx Well-Known Member

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  2. TEG

    TEG TMC Moderator

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  3. SByer

    SByer '08 #383

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    From experience, the stages of buying your first serious* LED bulb:

    Thinking about it:
    "Hmm. Really funky looking. Wonder if it works."

    Getting serious:
    "Boy, that's expensive. It better be more reliable than those **** CFLs. How the heck do I figure out if it's bright enough?"
    (Because, from buying CFLs, you know that the "watt equivalent" claimed is complete hooey.)

    Buying the thing:
    "Ouch. I hope I didn't make a huge mistake."

    Waiting:
    "Will it ever get here?"
    (Yes, that's right, the best bulbs can take weeks for delivery!)

    Opening the box:
    "Wow, looks better in person. Kinda like a sculpture or something. Do I hafta install it? It better darned well work."

    Installing it:
    "Oh. Wow. Happy... it's a happy light."
    (Seriously. That's the phrase that came to my mind. Blows CFLs away.)

    First couple of weeks:
    "Hey, ya gotta see this...", dragging friends over, and at other times with frequent staring up at the light as you flip the switch, hoping it'll still turn on (because, with decently bright CFLs, well... I'll just say there's a graveyard in the garage.)

    After a couple of weeks, when leaving the room:
    "Oh, right, that room has that bulb in it, I almost forgot..."

    Now:
    It's the best bulb in the house. The price still makes me cringe, but the light is so good I'm still tempted to just figure out what I want and replace every R38 in the house. And I think about how many that is, and I cringe. And somewhere my subconscious goes "it's so much better, you know it's inevitable". In a Mr. Smith voice, of course.

    Maybe if the CARB rebate program still has money in it when I get my car...


    (*) If it's got 40 crap LEDs in it, it's not serious.
     
  4. dpeilow

    dpeilow Moderator

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    Thanks for that. I've been contemplating spending 25 pounds on a decent GU10.

    BTW, as this would be 240v, have I just taken the thread off-topic?
     
  5. dpeilow

    dpeilow Moderator

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  6. graham

    graham Active Member

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  7. just-an-allusion

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    Yes, opt for the bulk pack, get them and get them swapped into all of your home fixtures and then get on with your life content in the knowledge that you're now living in a clearer, brighter, cooler, energy efficient environment while making your little spot on this world that much more worth while to live in not only for yourself, but also for the environment as a whole...give yourself a pat on the back (if you've no one around to do it for you).
     
  8. vfx

    vfx Well-Known Member

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    #8 vfx, Dec 27, 2008
    Last edited: Dec 27, 2008
  9. shark2k

    shark2k Member

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    #9 shark2k, Jan 4, 2009
    Last edited by a moderator: Jan 7, 2009
    Since you guys seem to know quite a bit about this stuff, I was wondering if this comment from the Auto Blog Green article is true:

    One commenter disagreed with this and I tend to agree with that person. They said that since LEDs are more efficient they would produce less heat. The reason I agree with this is because of incandescent lights being less efficient and the side effect of that is that they produce a lot of heat therefore getting pretty hot. So, I was just wondering if what that poster said was true. I am referencing comments 5-7 of the Auto Blog Green article posted by malcolm.

    -Shark2k
     
  10. doug

    doug Administrator / Head Moderator

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    Yes, it may be a bit counter intuitive, but heat dissipation for high power LEDs is a major issue.
     
  11. shark2k

    shark2k Member

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    That kind of sucks. Thanks for the info.

    -Shark2k
     
  12. Joseph

    Joseph Member

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    "Yes, it may be a bit counter intuitive, but heat dissipation for high power LEDs is a major issue."

    I'll also take you guys' word for this. (You do have an entire thread for LEDs, and I don't mean this one)

    Question: is the problem kinda like for electric motors? They may be 90% efficient, but in that tiny space, that wasted ten percent is alot of heat.
     
  13. TEG

    TEG TMC Moderator

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    #13 TEG, Jan 4, 2009
    Last edited: Jan 4, 2009
    Yeah, LEDs may be efficient, but when you start to pump lots of watts through one and it is minuscule in size you have a little issue of getting the heat away to a larger radiating area. This is the same sort of issue they have had getting heat away from more and more powerful CPUs in computers.

    An incandescent may be much less efficient but it tends to radiate heat out in all directions. An LED (on the other hand) is much better at putting out pure light, but the heat it does produce tends to build up right on the LED surface rather than naturally radiate away.

    Most LEDs just use passive cooling. In some cases they have a heat sink. In more extreme cases they have fan based air cooling. Someday they may actually want to liquid cool more LEDs just like Tesla may want to liquid cool the Tesla eMotor. It is all just a matter of finding the best way to conduct the heat away from the source and radiate it out to a larger area that is closer to ambient temperature. Some high end PCs now use liquid cooling for their CPUs.

    3002.jpg


    By the way,
    http://www.nzmustang.com/NewMustangs/shelby_gtr.htm
    [FONT=Verdana, Arial, Helvetica]

    And,
    http://www.eetasia.com/ART_8800480649_480700_NP_a3ec09f7.HTM
    [/FONT]
     
  14. WarpedOne

    WarpedOne Supreme Premier

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    Another point is that usual bulbs produce light because they are hot, really hot. Around 90% of energy goes into heat and only up to 10% into visible light.


    With LEDs it is almost completely the opposite situation. Only about 10% of energy goes into heat and around 90% into light. Problem is, LEDs must not be hot. Hotter they get, less light they will emit. Their working temps are around 20 to 25 degrees Celsious (normal room temperature). Pumping 10W into one and keeping it at 25 degrees ain't simple.
     
  15. TEG

    TEG TMC Moderator

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    Things like car engines (being mostly metal) and light bulbs (being mostly glass and metal) can stand up to the heat better. You don't want an LED to glow red hot like an exhaust manifold or turbo could be.
     
  16. doug

    doug Administrator / Head Moderator

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  17. TEG

    TEG TMC Moderator

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  18. TEG

    TEG TMC Moderator

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