Author Topic: AC and/or ceiling fan  (Read 1737 times)


  • 5 O'Clock Shadow
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AC and/or ceiling fan
« on: June 17, 2015, 12:21:02 PM »
I recently moved to a fairly hot/humid area and my bedroom has a built-in wall AC unit and a ceiling fan.  Over the past few weeks I noticed that if I have the ceiling fan on I'm comfortable with running the AC 2-3 degrees F warmer than without the fan.  In general would the electricity of running the overhead fan be worth the savings of the AC not needing to work as hard?  Both appliances are almost brand new and so hopefully are fairly efficient, but I don't have exact specs on either one.  I'm just curious if anyone here would happen to know if there is an obvious advantage of one to the other?


  • Magnum Stache
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Re: AC and/or ceiling fan
« Reply #1 on: June 17, 2015, 12:33:48 PM »
At the average national electricity cost of 12 cents per kilowatt-hour, a typical window air conditioner running 12 hours per day uses 335 kilowatt-hours per month and costs around $40 monthly to operate. A 2.5-ton common residential central air unit uses around 1,300 kilowatt-hours per month and costs just over $150. Now consider the humble fan. A midsize ceiling fan set on high for 12 hours per day costs just over a penny per hour in electricity or just about $3.50 per month. A higher revolutions-per-minute box fan adds just about $4.40 to your monthly electrical bill. In many homes, the cost of powering either fan for half of each day can be offset by the savings gained from simply switching incandescent light bulbs to compact fluorescent bulbs.


Given that every additional degree that you cool by increases the run time of the air conditioner even more (since it has to maintain a bigger delta, which increases heat flow through your walls), lopping off two or three degrees is substantial.


  • Walrus Stache
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Re: AC and/or ceiling fan
« Reply #2 on: June 18, 2015, 08:04:34 PM »
If it works for you then definitely do it.

The fan is not actually providing any temperature reduction of course (its actually WARMING the room slightly). But the thing is the human body is not cooled just by being in lower temperature air.. the air movement evaporates moisture from the skin.. so it feels cooler.

Eventually of course all that evaporated moisture raises the humidity level in the room and the air will be less effective at evaporating moisture.. so it won't work forever.. but it will work far a few hours.. Also the AC will start working harder to condense moisture out of the moist air... which in turn will cost more money to run the AC.

But for a few hours of additional perceived cooling is probably all you need.