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Energy savings lamp produce heat so what?

  1. Oct 11, 2009 #1
    I bought an energy savings lamp. The white wall really looks like daylight, but the bananas look green! I suppose it's impossible to recreate all colour impressions simultaneously without recreating the complete Planck spectrum.

    My question is: Why don't they allow normal light bulbs (in winter) so that people could turn down their normal heating system a bit??

    The electric heating is efficient and saves some normal heating by energy conservation. That seems to be perfect use of energy?!

    Or have I missed a point?
     
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  3. Oct 11, 2009 #2

    FredGarvin

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    You do realize that even at 100 watts, that's about 5.5 BTU/min of heat flow to the surroundings? Maybe if you had a hundred or so light bulbs on in a room you would come close to a space heater. You will never get the heat required to heat a house or even one room.
     
  4. Oct 11, 2009 #3
    You haven't understood. Hmm, or maybe I forgot to mention that 100W Wolfram light bulbs are forbidden in the EU which caused some controversy.
    I just turn down the heating *a bit*. The point is that I can still use the old-style light bulbs without having to worry about the "low efficiency" of these bulbs.
     
  5. Oct 11, 2009 #4
    I've often wondered about all the energy saving hype involving the new CFL bulbs. It's true that these bulbs are much more efficient than incandescent bulbs. But there is really no energy savings unless you live in a warm climate.
     
  6. Oct 11, 2009 #5

    Cleonis

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    Technically I agree with you. During times of the year that you are heating the house anyway the source of the energy makes no difference.

    On a more general note:
    I expect that in the future houses will be build that are so well insulated that the body heat of the inhabitants is sufficient to maintain the inside temperature. (Of course such a house needs special measures to prevent humidity problems.) You'd be surprised how soon that point is reached; the human body gives of lots of heat.

    In such a house normal light bulbs would reduce the energy efficiency.

    Cleonis
     
  7. Oct 11, 2009 #6

    f95toli

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    That is not quite true. Direct electric heating of ANY kind is usually quite inefficient for several reasons. From an environmental and financial point of view because you have to convert the energy to electricity first before converting it to heat meaning some energy is lost on the way. Very few people that live in very cold climates use electricity to heat their house (you can do but it is extremely expensive, I don't know of anyone who does it where I am from), most use thing like gas, oil or various forms of wood which heats water that is then pumped to radiators around the building. In many cities there are also power stations that only "produce" hot water that is then pumped to the residents (as opposed to boiling water->steam->generators->electricity->heat)

    Another problem with light bulbs is that they only give localized heating and often in the wrong place, WHERE you place the heat source in a room can make a huge difference, (underneath the windows is usually a good start). A well designed radiator will also allow air to pass through it heating the room more evenly, meaning even an electrical radiator is more efficient for heating than a light bulb.

    The key here is to remember that the room is not a closed system; we are not trying to ADD energy, just "replace" the heat that is lost in order to keep the temperature stable. It is really a dynamical system (and if you want to analyze it properly things like convection because of ventilation etc becomes important, so again where you place the heat source becomes important).
     
  8. Oct 11, 2009 #7
    Yes, you are correct. I forgot to think about the electrical generating source. However, it can still be said that the energy savings for someone living in a warm climate would be greater than for someone living in a cold climate. Air conditioners have to remove the extra heat produced by incandescent bulbs.
     
  9. Oct 11, 2009 #8

    russ_watters

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    You may also want to consider the "efficiency" of your heat - if you are in a relatively warm climate and use a heat pump, the "efficiency" (COP) is probably around 3:1.

    Even if you use gas or oil, the efficiency of your heater is probably so much higher than the efficiency of a similarly fired power plant that it is cheaper to use the gas or oil than straight electric heat (generally, natural gas is at worst half the price of electricity).
     
  10. Oct 12, 2009 #9
    But if the heat from light bulb is so small compared to a normal heating system, then why bother about it? This superfluos heating will cause a minute increase in resource consumptions? A conversion efficiency from resources to electricity of 50% only doubles the effective resource consumption.
    And the final electricity to heat conversion is absolutely efficient anyway.
     
  11. Oct 12, 2009 #10

    Pythagorean

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    As a side-note, my sustainability teacher predicted that a heat pump still ends in about the same emissions from the power plant as if you directly heated your place with electricity.

    He suggested an absorption chiller instead, which has a COP of only 1.2 (or 6:5 in ratio form) but doesn't require electricity.
     
  12. Oct 12, 2009 #11

    f95toli

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    Because electricity is -as I noted above- the most "refined" form of energy we have and should be used for other things instead. You simply shouldn't use electricity to heat your house directly (and if you must use electricity you should use it "indirectly" by heating the water in a boiler and then circulating that water, much more efficient than using electrical radiator when it comes to heating a house).

    Besides, even in "cold climates" people only heat their homes for part of the year (I grew up in the north of Sweden and there the heating systems probably are running for about 6 months per year or so, and then not constantly). This means that most of the time the heat is just wasted and even the the waste "per bulb" is small it all adds up, remember that when it comes the energy efficiency even saving of one percent of electricity can "translate" to several power stations for a whole country.

    But again, is it the "optimum" use of the heat? Heating a house properly requires -as I wrote above- quite a bit of engineering, WHERE you produce the heat makes a lot of difference since it it not a closed system, the aim is to heat the floor and the air in the rooms.

    Engineering question: Where I come many of the large hot water "producing" district heating plants (that heat whole towns) burn wood (usually wood chippings). But I have never seen a wood burning power station that produces electricity. Am I right to assume that this is because wood is fine for heating water to 80-90 degrees C (or whatever the temperature is when it leaves the power plant) but very inefficient for creating steam for a turbine?
     
    Last edited: Oct 12, 2009
  13. Oct 12, 2009 #12

    russ_watters

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    Do you mean if you heated your place with gas?
     
  14. Oct 12, 2009 #13

    A.T.

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    Yeah, but during the other 6 months you don't use much electric light, since it is 24h day anyway. :smile:

    Seriously, the energy savings lamps save money, not only trough the electricity bills: some work for almost 20 years in my parents home now.

    Problem is that they contain mercury and I bet most of them are not disposed of properly. And their production uses multiple time the energy a usual light bulb needs.

    It seems weird that many countries ban mercury-in-glass thermometers:
    http://en.wikipedia.org/wiki/Mercury-in-glass_thermometer#Phase_out
    but force the people to use mercury-in-glass lamps.
     
    Last edited: Oct 12, 2009
  15. Oct 12, 2009 #14
    f95toli, I think you have good clear arguments :smile: I hope it's OK if ask questions, so that we clear all counter-arguments.

    But unless the production capacity of electricity creation is reached, using individual bulbs as little heat sources effectively only means firing only slightly more resources (depending where the electricity comes from)?
    Of course, I do not propose to switch all the heating to electric. I just want my candescent light blub back for at least some of the rooms (which have yellow colours and look green in that new light)

    This is all true. However, that is similar to the "stand-by" mode argument. Some people are crazy about saving a little amount of energy by switch devices off instead of going to stand-by mode. But why don't they for example use public transport instead of their own car just *very few* times. That saves much more energy in one go?!
    Similarly the no-stand-by-mode choice seems a bit half-hearted to me.
    I'm trying to say that there are easier ways to save energy if one really wants to.

    In general I agree that heat should stay heat if possible and not be converted back and forth if not needed.
     
  16. Oct 12, 2009 #15

    Integral

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    Here in the US Pacific Northwest more and more of the sawmills are using their wood waste to generate electricity. It is done and has been done for many years.
     
  17. Oct 12, 2009 #16

    uart

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    Hi Gerenuk. Look around for some different types of compact fluro's. Different types/brands use different phosphors and some are decidedly more natural than others. Most of the ones that I have installed here are give off a light that looks very similar to the old incandescent type. I did install one "off brand" that had the that really greenish tinge that you mention, but all the others have been good. Look around for some different types.
     
  18. Oct 12, 2009 #17
    Ah, OK. My fault. I didn't pay attention. Apparently there are "daylight" bulbs and "soft" bulbs. They latter are just like "normal". Daylight is in fact blue and probably useful for offices. Blue light makes you awake.
     
  19. Oct 13, 2009 #18

    Pythagorean

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    I believe he was comparing a heat pump (w/ electric source) to oil furnaces and wood stoves at the time (popular in Alaska for economic reasons).
     
  20. Oct 13, 2009 #19
    I still can't understand why people are so hyped about all these CFL bulbs. True, environmentally more friendly, more efficient...but still not as good as LED. Why no talk about switching to LED lamps? or am I just looking in the wrong places?
     
  21. Oct 13, 2009 #20

    f95toli

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    Because LED bulbs are still very expensive(I've seen single bulbs that cost over £30 each) and lifetime was until quite recently an issue.
    LED is undoubtedly a better solution, but it will take a few years for the companies to ramp up production and the prices to come down.
    It always takes a few years for new technologies to make it from "initial launch" to mass market product.
     
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