Question: how much electricity does fan consume?
Answer: So if your fan is 70 watts output on its high setting and you always use this, divide 70 by 1000 = 0.07. You then times this number by the amount of hours you're using the fan. For example, if you're using it for 12 hours per night - 0.07kW x 12 hours = 0.84kW output.