OK, some math about lightbulbs and air conditioning and heating units-
Me being the crazy kid I am, I was reading a book the other day and thought about those tungsten-filament light bulbs(I think they are called incandescent...).
The information I am about to quote and post is from 2 books and the internet.
Lets say you have a 3 light-bulb fixture in each room of your house^(which has 12 rooms and 4 hallways with 4 bulbs each) and you use 100 watt bulbs(yea, its usually 120 or 80, I know, but 100 is simpler to work with).
An average incandescent light bulb ranges from 2-10 percent efficient*(e.g 10% of the electricity is converted to light). We will use 5% for simplicity. Almost all the remaining energy is converted to heat. So 3 light bulbs per fixture put out (95x 3) 285 watts of heat. Multiply that by the # of rooms in your house(12 for this example, a 3 bedroom 4 bathroom house, finished basement) gives 3420 watts of heat.
That excludes hallways- 4 bulbs each, 4 hallways, for total 16 bulbs- an additional 1520 watts of heat. That is 4940 watts of heat. Equal to running 5 kilowatt space heaters every day, while your AC is trying to work! That is insane!
OK, Ill admit 3 bulbs per room is pretty inaccurate. Ill use me house as an example to show actual statistics. I will not post each room, just total bulbs.
basement total- 25 bulbs, 20 65 w, 5 60 w. main level- 20, all 100W minus some lamps~, Upper level- 24 bulbs, 14 60 w 10 120 w.
Also although the bulb wattages aren't perfectly accurate(no I did not go look at each bulb. I guessed for many- I know the flood bulbs in basement are 65W, but I do not know the bulbs over the sink wattage- guessing at 60. I know the lamps are dual-setting 120 watt- 60 and 120 settings. Mostly used on 120 w, sometimes 60.
Also, lets not forget this- the human body puts out about 100w at rest(4 humans here at home), refrigerator is probably around 700w(it draws 850, motor is under 100w, almost all electricity is turned to heat in one way or another, plus its on 24-7. TV is on a lot( I don't watch it though..) so about 500w based on internet data for heat output of TV. Plus the 2 computers are about 50 each, not on all the time though. This includes the chargers and printer. the stove isn't super efficiant- note that it cools off and sends that heat into the kitchen air. Also note this- you heat stuff to cook and warm it. Very little of the heat is used to chemically alter the food. Most of it just warms it- and where does that heat go when it cools? Into the air, but its not on all the time, so I am going to say 200w. ! Plus the dishwasher(although that doesn't put out a lot, it only runs for an hour or so, so I am not going to count it). We have a small warm-blooded mammal with fur, probably puts out about 15-20w heat. the sun adds some through windows, hot showers, etc. are being ignored. So lets total this- 400w+700+500+100+200...=1600w. This is most likely wayyy under the real total, but I am not going to try to measure the heat coming from everything. I am ignoring the following sources of heat- cable box, cooling lightbulbs(after turning off), chemical reactions, washer/dryer, computer monitor, telephone, transformers/chargers(remember how hot they get?), showers, water heater heat loss, pipe heat loss, additional heat from humans due to physical activity, and many others.
so lightbulb total heat output= 5650
estimated other sources=1600
Total estimated heat= 7250 watts during the day, about half that at night.
AC is off at night though.
So lightbulbs do contribute a lot to the heat in your house! If you have a lot of stuff on, during the winter, and its not super cold outside, you could get by with very little heat.
BTW my data on appliances was obtained in 2 ways- internet and by looking at the wattages of each appliance.
Isn't it surprising that lightbulbs contribute a lot to cooling costs- about 70% from this example(77 by math, but other heat sources not added)- you not only save on electricity from lightbulbs by switching to efficient bulbs, but you also save on the AC cost of cooling the heated air generated by those bulbs! So double win!
Please remember that your house may be very different than these estimates. Most of the appliances in my house are fairly new, so they aren't too bad for heat production. Insulation also makes a big difference in cooling costs.
*This is luminous efficiancy- if every watt was converted into lumens (M) and measured lumen output from lightbulb(E), E over M= efficiancy. The actual efficiancy can be lower or higher by a small amount.
^Most rooms will have more lightbulbs that that. For example, the kitchen in my house has 2 3-bulb fixtures and a bulb over the sink and stove, for a total of 8 bulbs. The room I am typing this in has 1 3 bulb fixture, 2 flood bulbs, and 2 2-bulb lamps, total 9 bulbs)
~I counted the 2 bulb lamps as 1 bulb cause 1. They aren't on all the time. 2. They are only 60 w(x2=120W)
