I’m hoping there is a factual answer to this in terms of setting up airflow, but if this belongs in IMHO then please move it!
Here is a link to a rough layout of the upstairs of my house. 3 of the bedrooms have ceiling fans and there is a bigger fan above the stairs. One of the problems is that the house faces primarily North/South and our evening breezes tend to be East/West - note that we have no way to get that to blow through the house as the only West window is the small one in the bedroom.
What would be the best way to setup fans in the upstairs to maximize the airflow and cool down the upstairs? Should the ceiling fans be set to push air down or pull it up? My first thought would be to setup fans in each of the bedroom windows(this is in addition to using the ceiling fans), each facing in so they pull cool air from the outside and blow through the rooms into the central area. Then setup a fan to blow the air towards the stairs where there large ceiling fan can blow it downstairs.
I can’t put a ceiling fan in the master bedroom because it has a vaulted ceiling.
Is a south-facing attic fan an option or would the vaulted ceiling in the MBR be a problem? I know it’s outside your question, but attic fans are really quite amazing when it comes to cooling off the upstairs.
If you’re stuck on ceiling fans I’d suggest having them blow downward in the summer. That way you can lie naked and sweaty on the bed and have the fan blow on you.
When I said “I can’t” I really meant that as me… I’m sure it can be done, but I have no idea how to do it. I put a ceiling fan in one of the bedrooms and had enough problems even being able to work from above that I don’t want to try to tackle how to do it on a vaulted ceiling. Also, I don’t know if a ceiling fan in the master bedroom will help all that much.
We first have to understand that fans cannot ‘cool’ a/the house. They move air, nothing more, nothing less. Any cooling sensation is the result of air flow evaporating skin moisture. For this reason the air flow should be down in summer to blow on the occupants and up in the winter to circulate warm air from the ceiling to the walls and down to the floor and back up the center of the space. This requires that the fans must have a built in reversible feature.
Large spaces require larger/more fan(s) than small spaces.
Again: Care should be taken to ensure that the direction of airflow for these reversible fans is downward in summer and upward in the winter for maximum effectiveness.
Fans can certainly cool a house, if they aid in blowing hot air out and bringing cool air in. This sounds like what cmosdes wants to do. They can also help more evenly cool a house with air conditioning, if there are rooms that are hotter than others.
cmosdes, set up the fan over the stairs to pull air up, to aid in the natural flow of the air. You can also add window fans, blowing out on the second floor, and in on the first floor. When it’s cooler outside than inside, open the bedroom windows and doors, and the first floor windows as well, and turn on the fans. This will pull cool air in the first floor windows, and blow hot air out the upstairs windows. The downstairs will cool off first, but eventually, so will the upstairs.
Yes, but that’s not what ceiling fans do. Ceiling fans just circulate the same air to make you feel cooler, they don’t cool the room.
I suggest one of the whole-house fans. Here’s one that can install into a window, probably a DIY job. I don’t necessarily recommend this particular model, it’s just to illustrate the idea.
I use a portable one rather than one that installs. I put it in some room where I don’t care about the noise and set it up to blow out the window. Then I open the windows in the rooms I want to cool. The fan sucks the air through the house and the rooms where the cool air enters from outside cool off. (I also use it when I smoke up the kitchen, aim it out the kitchen window and open other windows to “feed” it.)
This assumes that the outside temperature is cooler than the inside temperature. which might not always be the case. One strategy is to run the fan at night then close up the house during the day.
What Z.B. describes is similar to what an attic fan accomplishes. As long as it’s cooler outside than inside this setup basically allows the heat in the house to naturally rise to the top and be exhausted out by the fans. And at the same time draws cooler air in through the downstairs windows.
Your problem of cross-ventilation when there is a breeze outside is really not a problem. As long as you have windows on opposite sides of the area you want to cool, and there is a breeze, a natural high to low pressure air flow will occur. The E-W wind you describe would have to be perfectly parallel to those windows for this to not occur. I have windows on the north and east side of my home and can get a good cross-wind going through in any outside wind condition.
First off, the OP mentioned putting fans in the windows, in addition to the ceiling fans, so we’re not talking about just ceiling fans here. Second, the OP says he has a ceiling fan over the stairs. That fan, as I said in my first post, can help to increase the airflow from the first floor to the second.
I was thinking about starting a thread like this myself, before my desktop melts.
My problem is that I’m on the second story of a 2-story apartment building, and my apartment easily tops 80 degrees during the day (in fact, it’s 10 p.m. right now and the temp is still 82 in here.)
The building faces roughly northwest, and the southeast wall has a large sliding glass door on it next to the fireplace. I tried foiling the door to reflect some of the sunlight out, but it hasn’t helped. The A/C has one vent in the living room, which is high up on the wall and right next to the sliding glass door.
The caulking/weatherstripping around the door is horrible (the building’s 30+ years old) but the bigger problem seems to be how the entire apartment heats up on its own no matter the time of day or outside temperature. I’ve had the entire apartment aired out down to 70 degrees, only to shut the door and watch the temperature rise 5 degrees in 10 minutes.
Any recommendations on what I could do? Building maintenance isn’t going to do a thing to fix minor problems, and I can’t really do a lot of home improvement myself.
brianjedi - wish I could help you, but obviously I’m no better at airflow than you are. Being on the second floor is probably at least as big a problem as the SE facing door, and obviously there isn’t a whole lot you can do about that.
I appreciate the suggestions from everyone else in here so far. An attic fan isn’t really an option as the outside fan would have face the front of the house. I don’t think I really want my house front with that on it.
I’ve considered room air conditioners, but installing them seems like it would be… troublesome as all but one of the windows are 15’ up in the air.
We had an apartment that faced E/W and I have to say… we never had a problem getting that cooled down at night. We opened the back and front door, the evening winds kicked in, and that apartment cooled down in about 20 minutes. Sleeping was never a problem there.
open the windows/doors on the shady side of the house Downstairs.
place a fan at the base of the stairs blowing up.
open the upstairs windows pretty much however you want as long as it doesnt let in more heat,
set a window fan to blow out someplace upstairs.
I would do this at my parents old big ass house. with a big fan pushing cool air upstairs things improved alot.
brianjedi, I suspect your problem is that there isn’t much insulation in the ceiling, and the heat building up in the attic (if there is one) from the Sun beating down on the roof is radiating down into the rooms from the ceilings. If so, the only solutions are more insulation, ventilating the attic more, or (since you probably can’t do the first two) lots of air flow to keep the heat level down.
cmosdes wrote:
I think when people are talking about an attic fan, they mean a whole-house fan, which is different. Whole-house fans suck air from the top floor of your house into the attic, and the hot attic air gets blown out through existing attic vents (which helps reduce the problem brianjedi seems to be having, also). I’ve seen versions of those that go in the attic access hole. They can cool your house off really quickly. Here’s a site that talks about them.
I have a few decades of practice at making cross-ventilation work, so I can give you the basics.
Find out which way the wind is blowing, and work with it, not against it. Even if you don’t have windows that match the wind, there’s a positive-to-negative pressure flow that matches the wind.
20 inch box fans are the basic tool, if your windows will open that high. If the window is wider than the fan, fill in the gap with cardboard. Put the fans in the downwind rooms, set to blow out.
Air will come in the window nearest the fan, so don’t have any other open windows in the fan room. Open the windows in the upwind room; they will pull in outside air, aided by the wind.
The sun will heat the house all day, and usually the outside air will be cooler than the inside. The residual heat in the roof makes it a good idea to keep running the fans after it’s a little too cool in the house. If you turn them off, the roof will reheat the house quickly.
Another way you could get this to work is to get air ‘blown in’ the downstairs windows and out the upstairs, using the ‘heat rises’ method to establish flow. By closing the other upstairs doors you can have a nice breaze of cooler downstairs air going through your bedroom.
You may also be able to use existing vents to blow air from the lower level to the upper.
Good advice, I have also graduated from the Cross Ventilation School of Hard Knocks.
Similar to electricity, the airflow is inversely proportional to the resistance between the window and the out-blowing fan. Resistance is lowered by a larger window opening and increased by distance from the window to the fan. So the farther from fan, the wider the window should be open.
