Cooling an urban apartment with a fan?
April 28, 2015 12:41 PM   Subscribe

Experienced urbanites: What is the best method to use a fan to cool an apartment that only has windows on one side of the building?

I just moved to my city's downtown and my new apartment has two windows with exposure on the same side of the building: one window is in the living room and one is in the bedroom. In the suburban apartments I've lived in, it's easy to get a draft going because you typically have windows on at least two sides of the building.

How can I best cool my apartment: a vornado fan on the floor? A box fan in the window? I have air conditioning (not a window unit), I'm just looking for a fan-based system of cooling my apartment so I'm not relying on the A/C as much.
posted by entropicamericana to Home & Garden (15 answers total) 8 users marked this as a favorite
I would say put a box fan in the bedroom window and blow it OUT. That will suck air all the thru the apartment and out that window, causing new, fresher air to be sucked IN through the living room room window.
posted by ThatCanadianGirl at 12:47 PM on April 28, 2015 [6 favorites]

A fan in the window blowing in for one room and another blowing out for the other.
posted by ssg at 12:56 PM on April 28, 2015 [4 favorites]

Yup, blow air out one window and suck air in the other.
posted by Jairus at 1:01 PM on April 28, 2015

You could try what my roommate and I did years ago in my first Chicago apartment -- we lived in a building that kept the halls aggressively cool, so we set up a box fan drawing air out of the unit and propped open the front door a bit. Instant free air conditioning, though maybe not the most responsible solution.

I live in a loft unit now that's a lot like what you describe, with windows only on one (comparatively narrow) side. When the air is noticeably cooler outside (particularly mornings and evenings, sometimes overnight) I use a box fan to draw the air in; when the air is warmer outside I reverse it to try to keep air moving in the unit without actively blowing in warm air. As ThatCanadianGirl says, you have a bit of an advantage with the two windows in separate rooms, blowing air out of one window should draw it in the other and keep at least a little bit of air moving between the two. I also use and recommend a tall vornado fan; move it around as needed to find the optimum spot (or just move it to wherever you happen to be).
posted by Two unicycles and some duct tape at 1:01 PM on April 28, 2015 [1 favorite]

What you do is keep the shades/curtains down/closed during the day so the apartment stays shaded and cooler. During the day, also, keep a fan in a window facing OUT so you're sucking air from potentially cooler lower floors.

At night, you do the opposite. Open the windows wide, and face the fan IN so you pull the cooler night air into the apartment.

Seriously. Try it. It works better than any other fan-based cooling method.
posted by rabbitrabbit at 1:28 PM on April 28, 2015 [3 favorites]

Some basic fan maths, assuming two windows.

1 fan blowing in one window at 1 fan units per second.
1 fan blowing out from the other window at 1 fan units per second.
This will result in 1 fan unit per second of air being exchanged.

2 fans blowing out from one window at 2 fan units per second.
No fans in the other window, but it is left open and is sucking air in because of those other 2 fans are lowering the air pressure.
This results in 2 fan unit per second of air being exchanged. Yay!

Use this to your advantage to put fans where you do want noise, and no fans where you do not want noise.

I would cool a house by opening one window in the bedroom, and a put a box fan blowing out at the opposite end of the house. All other windows must be closed.
posted by Diddly at 2:30 PM on April 28, 2015 [1 favorite]

And in Diddly's math, it really does make a difference between a fan IN the window and a fan NEAR the window. If you can get a window open >20 inches, go for the big old box fans. If you have weird windows you may have to go for a (slightly lower horsepower, I think) window fan.

I use the latter in my bedroom window most of the year, but in the hottest months will be using big box fans for maximum draw.
posted by Lyn Never at 2:37 PM on April 28, 2015

Response by poster: So the consensus seems to be that I'm best off having two fans, then?
posted by entropicamericana at 2:39 PM on April 28, 2015

Unless you're on a top floor, I'd stick with one box fan blowing out the living room window. The bedroom will get the cool air flowing in at night and it will be quieter.
posted by JoeZydeco at 2:44 PM on April 28, 2015

Lyn Never - correct. A fan near a window is just spinning air doing nothing. A fan in a window, sealed around the edges, will make a big difference by creating a pressure differential between inside and outside.
posted by Diddly at 3:05 PM on April 28, 2015 [1 favorite]

Oh gods. We had to do this with our old apartment - a brick monstrosity that was hot in the winter AND summer (we called it the Easy Bake Oven).

1. Agreed with the above, one fan blowing in, one out. We got some decent air circulation that way.

2. Keep blinds closed during the day to block some of the heat of the sun.

3. I found it helped a bit to have the fans all blow in at night. it helped bring cold air in at night... it seemed like it took the apt longer to heat the next day.

Side note... if you have Tiny Kitchen like we did, a dedicated kitchen fan to blow hot air out while cooking was a life saver.
posted by Verdandi at 3:52 PM on April 28, 2015

I lived in an apartment a lot like Verdandi described for a while. We had the BEEFIEST window fan. Most of those aren't very strong, this one was. After some searching, i think this is the new version of it(1400CFM is a lot for a fan like that).

Fan went in the kitchen/living room, and drew in fresh air from the bedroom. I preferred this to the reverse, because it kept a nice breeze of directly fresh air coming in my window, rather than cool-ish air pulled through the apartment about to be exhausted. That tended to be both cooler and fresher when i was in my bedroom. This also outsources the fan noise to your living room, and the older varient of that fan was actually very quiet on the lowest speed.

I left it on 24/7/365. Found it in a free pile when i moved in, and gave it away when i moved out. It ran non stop for 2+ years. I always considered something like this, but never needed it. Especially if you have AC to fall back on when it's truly hot.
posted by emptythought at 5:33 PM on April 28, 2015

I am the fan Queen. I have tower fans in the kitchen, my office, and my bedroom.

What I do in my office (which has one window) in the summer, is I have a tower fan in the doorway, and a mini vornado type on a little table on the other side. So I am fanned from the left and the right. I draw a curtain during warmer months.

When I am in the kitchen, a tower fan blowing in from the window on that side.

When in bed, a tower fan blowing, no matter if it's winter or summer.

I also have ceiling fans.

So my solution is to have a fan blowing at you from a doorway and another from the window. Dual fans.
posted by Marie Mon Dieu at 5:42 PM on April 28, 2015

Some basic fan maths, assuming two windows.

This is most definitely not how fans work. A fan will move less air the greater the pressure difference across it. Two fans removing air will lower the pressure and make it harder for both fans to remove more air. In a perfect, frictionless world, it wouldn't make any difference if the fans where two pointed out or one each way, but in the real world balanced is better.

No harm in trying just one fan at first, but you'll probably be happier with two so you can have balanced ventilation (and move more air).
posted by ssg at 7:13 PM on April 28, 2015

This Air King window fan (note: hard to find on their website) is like the best thing ever. Besides variable speeds (read: it has quieter speeds that aren't "typhoon"), it has a simple thermostat that turns the fan off after the temperature drops a bit (read: you don't wake up freezing because the temps dropped overnight). Accept no substitutes!
posted by intermod at 7:56 AM on April 29, 2015 [1 favorite]

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