Fan placement in room

June 21, 2005 10:31 AM

Hot outside, hot inside. One open window, one fan (like this one). Where do I place it to cool my room down most efficiently. By the window, or on the other side of the room? Or somewhere else?

The room is 15-20 square meters, and the open window is positioned here.

posted by mr.marx to home & garden (16 answers total)

This is all about air flow. A fan like that isn't going to really suck air in or out of the room, it's going to simply blow it around, no matter where you put it. I recommend you get a two box fans and do the following. (You can try this with the fan you've got, but it won't work that well.)

At night, open all windows. Put a fan in the window of the room you want the coolest, blowing into room. Put the second fan in a window that is at the other end of your apartment, put that fan blowing out. This will set up a flow of pulling cool air in, and exhausting hot air out.

In the morning, remove the fans and close all windows and pull all shades and curtains. (I know, it seems a little counter-intuitive to close the windows, but trust me, I've lived in 115+ degrees F.)
posted by Specklet at 10:46 AM on June 21, 2005

To cool the room down you need to pull cooler air from somewhere else. If it's horrible everywhere you need to move dry air across your skin to evaporate sweat (which you have even if you don't feel sweaty) to cool yourself.
posted by phearlez at 10:51 AM on June 21, 2005

Put a fan in the window of the room you want the coolest, blowing into room. Put the second fan in a window that is at the other end of your apartment, put that fan blowing out. This will set up a flow of pulling cool air in, and exhausting hot air out.

This is exactly what I do. It works remarkably well. (Assuming you don't live on the first floor in my old neighborhood - in which case one is cool, but too worried about leaving that other window open all night, to sleep.)
posted by R. Mutt at 11:11 AM on June 21, 2005

I just saw a link on del.icio.us/popular that had plans for making a $35 air conditioner with a 55 gallon garbage can, copper pipe, cold water, and a fan. FWIW.
posted by mecran01 at 11:17 AM on June 21, 2005

Like this, mecran01?
posted by amro at 11:37 AM on June 21, 2005

Here is your problem:

Hot outside, hot inside

You are just moving hot air around. Unless there is no humidity, moving the air ain't gonna help much. I suggest you go sit in the shade and sip lemonade.
posted by Pollomacho at 12:46 PM on June 21, 2005

For $20, you can buy a much larger fan that will really move some air.
posted by smackfu at 1:05 PM on June 21, 2005

Ice bucket from your freezer (or, ideally, frozen 3-liter bottles) in front of the fan. Works like a charm.
posted by Who_Am_I at 2:13 PM on June 21, 2005

I just saw a link on del.icio.us/popular that had plans for making a $35 air conditioner with a 55 gallon garbage can, copper pipe, cold water, and a fan. FWIW.

Yeah, I should've said I live in an apartment, on the fourth floor.

And I have only one room.

So I'll try the ice bucket first. Thanks everyone!
posted by mr.marx at 2:34 PM on June 21, 2005

Ice bucket from your freezer (or, ideally, frozen 3-liter bottles) in front of the fan. Works like a charm. - Who_Am_I

Yes, feels great. But it isn't going to get you any further ahead once you need to freeze some more ice, is it? Because to make more water into ice, doesn't the freezer just suck the heat out of the water and throw it into the room through the back of the fridge (plus the additional heat generated by the energy expended to work the compressor and fans in the fridge)?* This is the same reason you wouldn't just open a fridge door to cool your apartment. Air conditioners actually move the heat outside the room, but a fridge isn't designed this way.

You could get around this problem by buying the ice from somewhere else so the heat generated by cooling isn't thrown back into your apartment. That would get expensive and cumbersome fast. But you know, desperate times lead to desperate measures and all that...

*it's possible I'm talking out of my ass here. But this is approximately how I understood fridges to work. Someone will correct me if I'm wrong.
posted by raedyn at 4:07 PM on June 21, 2005

raedyn- no no, you're right.

Actually, using your refrigerator to cool yourself off adds more heat to the apartment, because besides the heat removed from the water to make ice, the compressor motor gives off heat when it operates. It's not ultimately effective.
posted by Kirth Gerson at 4:33 PM on June 21, 2005

Because to make more water into ice, doesn't the freezer just suck the heat out of the water and throw it into the room through the back of the fridge

Maybe you can get around that by freezing the bottles of water during the day when you're not there, and then using them at night?
posted by mediareport at 9:08 PM on June 21, 2005

Cool air falls. Warm air rises. If there's any flow at all through that window, the coolest air in your apartment will be at or below the bottom half of your window, while warmish air runs out the top half. Position your bed under the window. (If you're attractive, do your neighbors a favor and leave the curtains open.)

If you still need the fan, put it on the sill, blowing down into your room and, if you're in bed, across your skin. Also, the fan generates a bit of its own heat, but leaving it on the sill will help let the fan's heat out. Don't use the back-and-forth setting on the fan. You want to set up a current, not a lot of random turbulence. Figure out where you want the cool air to go and point the fan in that direction.

But if that window is your only opening to the outside world other than your door, you should also try to use your door, assuming there's some ventilation beyond your door. Just open the door, stand there a minute or two, act casually, read the paper or pretend you're oiling the hinges or something, and then close it again. Give the place time to exchange all the air in your apartment. If the stairwell has a window or door to the outside that could be left open, do that.
posted by pracowity at 4:29 AM on June 22, 2005

You guys are right about the ice/freezer/fan method producing more heat overall, but we are talking about one room which is too warm and presumably needs to be occupied. Our corner office is much warmer than the rest of our apartment, and I have to be in here all day, so it is worth it to me to produce net heat in order to make this room cooler. I assumed mr.marx was dealing with a similar situation, but perhaps not. And to be fair, making ice in the freezer has never made my apartment noticably warmer, but that ice-air feels really good.
posted by Who_Am_I at 5:17 AM on June 22, 2005

making ice in the freezer has never made my apartment noticeably warmer

Maybe it has but you've never tried measuring the temperature of your apartment with the freezer turned off. The heat has to go somewhere.

Fridges should be made with a condenser and motor that can be separated (on extensions) and placed outside the house (through a window or whatever) or down in the basement. Otherwise the heat (and noise) generated by the fridge, as well as the heat removed from inside the fridge, are released right behind the fridge.
posted by pracowity at 11:18 AM on June 22, 2005

I seem to get the best results with a two-fan method as follows:

* An exhaust fan positioned at the hottest part of the house but away from the favored living space (i.e. office or bedroom); open a window where you can get the strongest or coolest airflow.

* A circulation fan in the living space. Ceiling fans work well but require installation; I use a little Vornado or a floor fan. (The Vornado wasn't expensive, and has lasted me years. I lube the axle every season.)

This both gets air moving through the apartment or house, getting the hottest outside, but in the space you're spending time it's actually more important to get the air moving up and down rather than through. It will get mixed with the through air better and cool the room faster.

Fridges should be made with a condenser ... placed outside the house

Absolutely. The biggest source of energy is conservation, and this is a really, really big area of excess heat generation. The problem is bringing it in during the winter, in climates where that's the case; then you want the extra heat.
posted by dhartung at 9:28 PM on June 22, 2005