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Do light bulbs affect cooling?

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  • Do light bulbs affect cooling?

    I don’t know where to put this so I’ll just ask here.

    I have read somewhere that incandescent bulbs give off so much heat that they affect cooling and may overwork ACs. Is this true? If so, how do I determine if these bulbs are affecting my cooling setup?

    A friend of mine recommended LED lights, saying that they give off lesser heat. I looked around and realized that prices for LED bulbs vary a lot. I found some on ebay but they were all Chinese made so I wasn’t sure about the quality (are they ok?). Right now I might go for bulbs from ikea like these LED Lights, LED Bulbs and Strip Lights | Shop at IKEA or the more specialized ones from LED Light | Illustra Lighting | Illustra Lights.

  • #2
    Re: Do light bulbs affect cooling?

    from a quick search the average 100 watt bulb aperently puts out about 341 BTU of heat,

    the average incondesent is about 2.1% effecent according to one site, (2.1 to light the reast to heat) a halagen about 3.5% and floresents about 8.2% Incandescent light bulb - Wikipedia, the free encyclopedia

    so if you have 10, 100 watt bulbs going it would be close to having a 1000 watt space heater running in the room your trying to AC,
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    • #3
      Re: Do light bulbs affect cooling?

      Yes, bulbs can affect AC loads. In most residential situations it's not such a huge issue. Unless you have a room full of lamps or a ceiling full of lighting you will not have a problem. I think your friend is basing this on the energy savings hype - 'incandescents make more heat than light! save energy by buying our 10 times more expensive LED replacements!!' though, a good example of this is any big box store's lighting section. there is an immediate temperature increase that you can feel.

      Be aware that any lighting you purchase from overseas is rated for 50 Hz 220 volts. It will not work here in the US. Most lighting products are made in China. Quality obviously varies. It's hit and miss.

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      • #4
        Re: Do light bulbs affect cooling?

        BHD gave you all the technical stuff, which is very correct. Let me just say that incondescent bulbs (traditional light bulbs) are definitely HOT. You no doubt have noticed that you can't touch them while they are lit and when they blow, you have to wait a few minutes for that heat to dissipate! So when the bulb is lit, that heat dissipation is constantly there... and is adding heat to the room. (If you ever had an "Easy Bake Oven" when you were a kid, you know that the bulb's heat can literally bake a cake!)

        My den is 10 x 12 ft, and though it is insulated quite well, a single 60-watt bulb, along with my computer can make that room unbearable hot in the summer months without an air conditioner. Even with the air conditioner, I find myself turning off the desk lamp in the evening to keep the heat down.

        Regarding foriegn-made light bulbs... if they are carried by your local retailer, then they are useable here in the U.S. and you should have no concerns. I'm really not sure whether a foreign light bulb would have any problems here, other that perhaps not being as bright as the rating or if they will even fit your lamps. Bulbs are pretty simple when compared to other electrical appliances in that they do not have motors or circuits designed for European-only electical generators.

        But keep in mind that efficiency is best with the LED bulb and thier great value is not only in thier low power (Watt) requirements but also in thier longevity... upwards of 50,000 hours in most cases. A good "inbetween" and less costly bulb is the compact florescent (called CFL's). They take considerably less electricity than old-fashioned incandescents and thus they put out much less heat for the amount of light given... but, they are still fairly warm.

        Whatever you choose, bear in mind the color temperature of the bulbs that you are looking for. Most of us are used to the "warm" color of incondescents and without knowing may just go buy a new technology bulb like the CFL or the LED and find them to be too harsh in color, even almost blue-white. Both CFL's and LED's come in different "colors"... and you need to look for that on the label. 2800 - 3200K are "warm" and very much like your typical incondescent bulb. The higher the "K" (Kelvin) value, the whiter the bulb gets, with 5000 K being relatively close to "daylight"... as you go over the 5000 K number the bulbs lean toward be blue-white. Lowes (and perhaps others) has a very nice display showing examples of these light differences.

        I hope this helps,



        • #5
          Re: Do light bulbs affect cooling?

          Good point CWS regarding bulb colour. I purchased 6 cfl bulbs for a front hall light, it was the end of the day, I was tired and not paying too much attention as I purchased them. I got home put them in, turned on the light and with in a few minutes the front hall was so bright it was actually hard on the eyes. I ended up going back to the store the same night and buying the warmer, brownish tone bulbs. I now use the super bright bulbs in my basement,


          • #6
            Re: Do light bulbs affect cooling?

            First of all, thank you guys for the very informative replies! To be honest I knew that it does affect cooling but I just wanted to see if there’s a way to actually calculate the amount of heat from incandescent bulbs competing with the AC. Thanks BHD for the technical data!

            Plumber Punky, now that you mention it, my friend indeed is into saving the planet stuff. Not that I don’t agree with her, it’s just that I didn’t see its connection to light bulbs until I saw the specs of today’s LED bulbs, lol. As for buying overseas, yes voltage rating was one of my concerns also though I was more focused on quality. I didn’t want to end up with a bulb that is rated for 50,000 hours but lasts a week only.

            CWSmith, the only rooms in our house with ACs are the bedrooms, play area, and my husband’s office and in these rooms there are no less than 5 bulbs with wattage ranging from 50-100W. A bit too much, I know, but it is in these areas that we prefer to be well-lighted. 

            I agree about LED efficiency, was in fact surprised at how much it has developed in such a short time. I remember when it was first introduced me and my husband didn’t like it much as the light it emits is very inferior compared to incandescent. I have already ordered from Illustra their warm whites and 2 of the daylight just for comparison. If it meets my standards then I’m going to change all my bulbs to LED.

            Again, thanks everyone for your input and advice!