Do light bulbs create enough heat to make an overall difference in the room temperature?

Question

Alright, so my older brother is a huge jack-*** and control freak. Being that it has been quite hot lately, he gets pissed when the lights are on. In his own words:

'Turn off those lights! It's hot enough in here as it is, having those things on are making it hotter!'

I'm not quite sure what type of light bulbs we have, but My mum said they're 100 watts, and something about 'air purifier bulbs'. They look like the energy saver bulbs. So yeah. They're not heat lamps or anything like that. Just your basic light bulb.
I was wondering if having 1-2 lights on would really make a difference in the overall room temperature.
I just want to prove to him that he is NOT God and DOES NOT know everything in the world.
Please list where you got your information, if any.
Thanks.

Answer 1

My source is common sense, as well as being an Electronics Technician, as well as holding professional licenses for Commercial radio.

Your brother is being exactly what you say he is being. He radiates more heat than 2-100 watt bulbs do. What ever heat they produce is going to come from infra-red, as well as basic radiant heat. If the room were a sealed room that was air tight, as well as super insulated, those 2 lamps, on all the time, might make a slight difference in a day or 2. Since I doubt your house is that air tight, and well insulated, any difference is psychological in nature, and not from "real" heat the bulbs generate. Besides, their heat is going to stay near the ceiling, since hot air, rises. You might want to suggest that if he stays in one place, keeps quiet, and does absolutely nothing, except breathe, he would be a lot cooler. If he wants things to be cooler, invite him to go buy LED lamps. They are available, a bit pricey, but they do exist, and would seem to be a bit cooler. Personally, his keeping quiet is the best idea. If you want a demonstration, get a thermometer, him and some of his friends to go out and exercise, then put them in a relatively small room. Check the temperature with them before they go out, and then let them see what the temperature is once they return, and gather in the room. If it is small enough, you will see a temperature rise, from their body heat. You might also tell him to stay out of your room because he only adds to the heat in it.

Half a degree would not even be noticed, unless you had a really accurate thermometer. Feel free to tell him that I agree with you.

Answer 2

The efficiency of a bulb is around 20%. So 80% comes off as heat. Your 60W bulb is like a 48W heater. From one ad on small heater: "The Presto Parabolic Heat Dish is a cost effective choice for workshops or garages when you want to heat just you and not the entire building. The Cozy Legs radiant heat panel, with only 100 watts of heat output is by no means a whole room heater, but performs admirably when installed under a desk or hung on the wall to warm a bird cage." From here we can see that the 60W bulb is about 1/2 the power of this "personal" heater. So yes if you are near the bulb, and not as much if you have a big room. You may wish to change the bulb to a fluorescent light which is 5X more efficient and you would not have this problem of heat. Additionally, your energy savings ($$$) will be significant over time and you are also helping the environment.

Answer 3

Your brother, just sitting around picking his nose will generate a little more than 100 watts. If he is stomping around shouting and waving his arms in the air, about 400-500 watts, depending on the volume of his screetching and the width of his "you-know- what".

Any heating discomfort of a single 100 watt reading bulb will be felt by the person closest to it- you. There is no way at this time to calculate the percent difference it will make in the total cooling load for that room. However, I would guess it would be insignificant.

When it comes time to change the bulb when it burns out do get the energy efficient ones. Ther are not that expensive if you pay attention.

If "Big Bozo" insists on an immediate change of hardware, show him Lowe's and let him spend some of his beer money.

Answer 4

Yes a 100 watt bulb is a very significant amount of heat source--depends on where you live ---in the hot tropics it would be cause for concern--In Alaska it wouldn't matter---your brother is right for once--also consider the cost of electricity---It would be a good idea to replace the 100 watt bulb with a 30 watt energy saving compact fluorescent lamp(CFL) which will run cooler and give the same amount of light.

Answer 5

Wattage is a measure of power, or the rate that energy is generated/used. In SI units, energy is measured in joules. A joule is the amount of energy it takes to raise 1 cubic centimeter of water by 1 degree Celsius.



Air has a heat capacity of about 1 joule per gram per degree Celsius. A small room might have 37 cubic meters of air in it. Air's density is about 1.2 kilograms per cubic meter, so there are about 44000 grams of air in the room.



The heat capacity tells us that it would take 44000 joules to raise the temperature of the air in the room by 1 degree Celsius (ignoring heating the walls and all the objects in the room).



In SI units, 1 watt = 1 joule per second, so a 100-watt bulb emits 100 joules of energy per second. Assuming all of this energy goes into heating the air in the room, it would take 44000 / 100 = 440 seconds to heat the room by 1 degree Celsius. 440 seconds is 7.3 minutes. That means after an hour, the lightbulb would have heated the air by 8.2 degrees Celsius.



A 100-watt bulb is actually a significant source of heat.



Of course, this isn't the full story. Heat is conducted, convected, and radiated away constantly, so the bulb probably wouldn't raise the temperature more than a couple degrees C. To get an exact answer, you'd need to do some highly-controlled experiments, or complex computer simulations.

Answer 6

Using a 100W bulb will heat the room,but by a few degrees.Try using CFL bulbs and see what ur brother says.

Answer 7

Yes, they are, and big time.

Changing incandescent lamps to fluorescent ones, and now LED lamps, you not only save energy consumed by the lamp, as well save twice this energy to the air conditioned that right now doesn't need to refrigerate this extra heat generated by the lamps... so it is 3 times savings...

Answer 8

actually they can. unless they are flourescent. then they wont. regular everyday light bulbs create lots of heat. nowhere near as much as an oven though. only like half a degree or so.



he was probably just pissed because he was so hot.



i just know.



make it a good day

Answer 9

having lights such as a ceiling fan, lamp, etc. only increases the average temperature by half a degree at the most. you shouldnt be able to tell a difference on or off.

Answer 10

I've often thought about this myself. I have no scientific evidence but, I think the dark just makes people feel cooler - brighter reminds people of the sun so they feel hotter.

Answer 11

thanks for the answers EVERYONE xx