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Over the years, my family has built up a small stockpile of incandescent light bulbs. More recently, we have been replacing our incandescent lights with more energy-efficient alternatives. Nevertheless, there are still plenty of unused incandescent bulbs in our closet.

What is the most environmentally-friendly thing to do with these bulbs? Letting them sit unused indefinitely seems like a waste, especially given the energy and resources it took to produce the bulbs. Still, using them in our home also seems wasteful, since we already own more efficient bulbs that we could be using instead.

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    Welcome to Sustainable Living! There is a related but slightly different question that only asks about recycling: Are incandescent light bulbs recyclable?. Perhaps some of the answers there will help you? Answers here should also focus on other options (e.g. reuse) – THelper May 11 '15 at 7:22
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    I don't know where you are from, but if you have cold winters you could consider using them in a low situated reading-light. Where I live, gas is going up in price, and electrical heaters are starting to compete again. I do the same with my desktop computer, in the winter it can keep my room a few degrees warmer while doing heavy computations. Of course those computations should be useful, not just to keep the room warm, likewise don't keep the light on just for the warmth :-) – Louis Somers May 23 '15 at 22:33
  • Welp, I heard that incandescent light bulbs are tough to find and information is out that these 'energy saving' bulbs are environmentally hostile. I've heard one should go buy any incandescent bulbs available. Seriously, do more research before getting rid of your incandescent bulbs! – stormy Jul 22 '16 at 6:34
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TLDR; don't use them for lighting.

Given that you could keep your incandescent bulbs for when your current energy-efficient (I will assume CCFL) bulbs need replacing, your choice boils down to: buy a new CCFL; or use an incandescent that has already been manufactured.

This helpful analysis gives the embodied energy in a CCFL as 1.7 kWh. Let's assume that the CCFL lasts 8000 hours and uses 15W, while your equivalent incandescent lasts 1000 hours and uses 60W (also from the same source, though these are pretty standard numbers). Total energy usage (in kWh) is:

                            CCFL                 Incandescent
embodied energy             1.7                  n/a as "sunk cost"   
energy used over lifetime   8000 * 0.015 = 120   1000 * 0.06 = 60     
total over lifetime         121.7                60                   
total over 8000 hours       121.7                480                  

So you're better off not using the incandescents for lighting, even though that means buying new CCFLs. That's because the energy to produce the bulbs is dwarfed by the energy used in using one. The comparison would be even starker for LEDs as these are even more efficient.

The question remains, what should you do with them, if not lighting?

  • You could use them for applications where the heat is useful, not wasted (this could include lighting your home - provided you are also heating it around the same times you are lighting it)
  • You may be able to recycle them (see e.g. this question)
  • You could just throw them into landfill. Being largely glass and metal, at least they won't break down to produce greenhouse gases like methane
  • You could sell them, though given that incandescent bulbs are being outlawed (in Europe) this may enable someone to use them who would otherwise have been forced to use a CCFL or LED, so there may be an indirect energy cost there. The embodied energy in an incandescent bulb is about 0.3 kWh, so really quite small.
  • You could keep them in the attic until long after all incandescent bulbs have been outlawed, then donate them to a museum ;-)
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    Where the heat is useful, not wasted” – would that not include any time you are heating your house with externally generated energy? (I.e. cold outside, not a passivhaus.) Would this then not be preferrable to putting them in landfill? If so, I suggest explicitly mentioning that and bumping it up your list. – PJTraill Jul 19 '16 at 20:20
  • @PJTraill : I think it depends on where that externally generated energy comes from. For example if you normally heat your home with natural gas, and your electricity comes mostly from coal plants (which generally produce more CO2 than natural gas), it might be better to minimize the amount of heating you get from electricity and use a little more gas instead. – Lily Finley Apr 18 at 14:24
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I use them in garden/indoor. Something like this...

Moneyplant

(source : google search)

  • That's unbelievably cool! Well done. – FreeText Jan 11 at 0:17
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I disagree with the answers that say not to use it. It may in fact be an excellent idea to use it if:

  • you live somewhere that requires your home to be heated in the winter
  • you currently heat with electricity or with something less efficient than electricity

The "wasted" energy from an incandescent bulb is wasted as heat. In the summer, this is really bad since at best it is thrown away and at worst it might cause you to use energy in cooling. But in the winter, the bulb is a tiny little electric furnace, with about the same efficiency as other electric heating approaches.

Whether you throw the bulb away unused or use it has no effect on the materials and energy used to make it. But if using it will save overall energy consumption (by enabling you to use less of a less-efficient heating approach) then you should use it before throwing it away. If you heat with electricity, then by using it before throwing it away you are not saving any energy, but you are postponing the time when you'll need to buy more "regular" (efficient LED probably) light bulbs, thus saving (a probably minuscule but non zero amount of) money.

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Osram did a good comparative life cycle assessment on bulbs, including incandescent, CFLs, and LEDs. The total life cycle impacts of CFLs and LEDs are both significantly lesser in all categories than incandescent bulbs, meaning that the very best thing you can do with an incandescent bulb is not use it even if it's already been manufactured!

They are generally safe to put in landfills. Most incandescent bulbs have tungsten in the filament, which is fairly valuable, but most metal recycling facilities do not separate tungsten and it ends up in the landfill as process waste, anyway. Universities and R&D organizations are working on various ways to separate rarer metals from waste, but the technology is not yet widely used. Where it is used, it's generally for the more valuable metals like platinum, gold, and such. :(

Short answer: chuck it in the trash.

The executive summary of Osram's LCA can be downloaded as a PDF from here: http://seeds4green.net/sites/default/files/OSRAM_LED_LCA_Summary_November_2009.pdf

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Please consider donating incandescent bulbs to a support group for diseases that can sensitize some people to light. One disease with fairly widespread support group chapters is Lupus.

Lupus has various manifestations, but some individuals with it develop headaches, weakness, and/or rashes when exposed to direct sunlight or fluorescent lights, or even cool LEDs. Incandescent lights are usually well-tolerated. So your stockpile of incandescent bulbs can be a boon to them.

In the Chicago area, I donated my mother’s incandescent bulbs to the Lupus Society of Illinois.

  • This is very interesting. Out of curiosity, do you know of a reputable site that maintains a list of the warmest LED bulbs? I have sleep cycle problems that are worsened by lots of nighttime exposure to cooler light. – Lily Finley Apr 16 at 11:31
  • This is interesting, but unfortunately not an answer to the question, which (in the body, if not the title) asks for the most environmentally friendly use. If you can afford to do so, it would be better to donate appropriate (suitably warm) LEDs. – PJTraill Apr 19 at 15:04
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I would hold a few in reserve in case you ever find a need for them. For instance, I used an 85W incandescent bulb and a steel coffee can to create a small "space heater" for young chicks (chickens).

The rest can probably be sold via Craigslist, eBay, or similar. There are still people unwilling to change to more efficient lighting, and those bulbs will at least get used that way.

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What to do with existing stock of incandescent bulbs – use them up or just put an LED in any socket where a lamp burns out?

As efficient LED bulbs are widely available the question comes up what is the most economical way to transition, if a household still has some “stock” of previously purchased incandescent bulbs. A white paper published by Forestfern.org examines various transition strategies such as

  • replacing any bulb with an LED every time when a bulb burns out even though existing stock of incandescent still exists

  • using up existing bulbs first before buying any new LED

  • employing a replacement strategy based on “use frequency” of sockets.

Forestfern.org has found that the most economical way is to employ a replacement strategy based on “average daily use” of the sockets. Replacing burnt out bulbs with existing stock of incandescent bulbs in sockets that are used “infrequently” and purchasing LED-s for sockets that are used “frequently” maximizes the savings achievable in a 5 year period. Examples of sockets used “infrequently” are attic lights, lights in a walk-in closet or other areas where a light source is used on average for less than an hour per day. Sockets that are used “frequently” are those that are used on average more than an hour daily, for example living room, desk lights etc.

Please check the following very short, 1 minute video about what to do with old incandescent bulbs and make sure to check out the "Transition to LED" tab. Forestfern.org

  • There's another beneift to using incandescents in an attic over CFLs: Attics can get cold enough that CFLs don't start or take ages to get bright enough to use, and when your attic is cold you don't want to leave the hatch open any longer that absolutely necssary while you wait for the light to warm up. Of course, LEDs don't have this problem, but are expensive. If your attic is infrequently used then the bulbs can go there to die. I reckon mine averages less than an hour of use per month; the payback period would be infinite in cash terms. Same for cold cellars, outbuildings etc. – Chris H Jan 29 '16 at 15:06
  • The forestfern.org article is about saving money, but this question is about saving the environment, so I think this is not really useful (though @ChrisH makes an interesting point about cold attics in the era of CFLs). – PJTraill Apr 19 at 14:57
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I have one light that is my old bulb user. I figure it does cost more to use them but I get use out of them. I only have one light that uses incandescent bulbs. I kind of use it as a shrine to ancient tech and a way of comparing the quality of light of LED bulbs I buy. So I have 32 lights in my house, 30 of them are LED and 1 is incandescent and one is CFL. I have 30 CFL bulbs and 180 (don't ask why but if you must know contractors that built my house left a pile in my attic) incandescent. So I will just feed the respective lights replacements of like type until they are gone. Not saying this is the best way to save energy but IMHO it is nice to have some old technology for comparison and a shrine to inefficiency to remind you of why you changed.

  • I use a similar strategy, however my old CFLs and incandescent bulbs are used for closets, hallways, the attic, and the basement -- places where I don't often use lights, so total energy usage on an annual basis is low. – LShaver Aug 16 '18 at 0:02
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If you’re not crafty yourself, you can sell them to crafters. The sites I can think of are Etsy (you can sell supplies there) and EBay, but if you google “repurpose incandescent bulbs” that may lead to a few sources directly. If not, it will at least lead to bloggers who you can message asking about where to sell.

Also check your state and county government websites. Mine offer lightbulb take-back days and sometimes let you trade in X incandescent bulbs for an LED.

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