about $5-$10 actually per fan for 120 hours of usage (or like 5 hours a day) so maybe $20 a month per fan if used 24/7. if you want to get very exact, you can buy a $25 watt measurer. it might be a smart investment to coax your grandma into using certain products. or, if you don't want to do that, buy $25 in energy efficient lightbulbs - should be enough to change out all the lights in an apartment. the lightbulb savings would probably equal out with the cost of the fan.

It depends on the size of the fan and on the speed setting, but usually 50 to 100 W. The important thing about the question is that if you can keep cool using the fan and run the air conditioner less, it will save a lot of money and energy as most air conditioners use 20 to 50 times that amount of energy.

My 20 inch box fan uses 40 watts on low and about 90 watts on high (measured by a Kill-A-Watt meter).

DK

drbdr

out neighbors bill is always (we live in an apartment complex) is always about 30 bucks cheaper than ours. only thing I can think of is maybe this box fan. does anyone know how much power they use?