How do I make an effective cross-breeze in the house?


Old 07-17-11, 07:30 PM
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Join Date: Jul 2011
Location: US
Posts: 12
How do I make an effective cross-breeze in the house?

I'm without AC, it's bedtime and the thermostat has not gone below 92 degrees for several hours. That's on the ground floor and it's much warmer upstairs where my bedroom is.

I really want to get the house cooled down tonight while the sun is gone.

I have every window open, every ceiling fan going, and a window fan upstairs.

Do I point the window fan inside or out?

Is having every window open counterproductive to getting a cross breeze?
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Old 07-17-11, 10:05 PM
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
Our summers have been relatively cool last couple of years but what I would suggest is that you get a couple of the 20 inch box fans and install them in windows upstairs. close the window against the fan and use cardboard to close off any large gaps. Have the fans blowing outward. Open windows on the ground floor as long as there isn't a security problem and be sure you have screens on the windows.

Start the fans as soon as the outside temperature drops below the inside temperature and keep them running all night if possible. Using more fans will allow you to run them at a slower speed and still get a large air interchange, you need to move a lot of air to get the benefit. It IS imperative that the fans be tight in the windows with the cardboard (or plywood would be even better) so that no air comes in around the fan but must come from the open windows downstairs.

If security IS a problem and you don't want the ground floor windows open then you can do just the upper floor. Install the fans in a window on one end/side of the house and open the windows in the other rooms. If you use open windows in the bedrooms and can have the fans in a spare room it will be less noisy for sleeping. The downstairs, of course, won't cool much under this usage.

Be prepared though to get a lot of dust from the outside drawn throughout the house. I haven't tried it but using cheap furnace filters on the open windows might help in dust control.

Of course this only works if the outside temperature drops significantly when the sun goes down. I've used this system to drop the inside temperature of my house 10-15 degrees and it was enough to allow me to sleep in relative comfort and not be miserable until late the next day. Unfortunately it does nothing about the relative humidity so if that is a problem (it rarely is in my area) it may drop the temperature but still leave you miserable.

Also, any east-facing windows need to have heavy drapes closed in the morning and the same for west-facing windows in the late afternoon and early evening. The solar gain through unshaded windows can be murder.

I know that you will hate me for this but right now I have the heat on to maintain 70 degrees inside. I haven't been able to go three days this year without having the heat on.
Old 07-18-11, 08:22 AM
Beachboy's Avatar
Join Date: Nov 2006
Location: Northeast Kansas
Posts: 735
Furd, you must be the exception this time of year for needing heat in mid-July

Right now here in the midwest, we're caught in a heat wave that's been going on for two weeks and is projected to last one more week. The predicted high temps in my area are all over 100 degrees this week (as they were last week, with some communities seeing 115 degrees). Last night, the thermometer was still at 100 degrees at 10 PM when I went to bed. Thankfully, I have AC and can't imagine anyone trying to exist otherwise. In these kind of temps, no amount of cross ventilation is going to help much. Time to crack open a cold one
Old 07-18-11, 09:14 AM
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
You might enjoy reading this blog from one of the meteorologists at a local television station. Seattle: Home of the 78-minute summer | Seattle News, Weather, Sports, Breaking News | KOMO News | Weather Blog Notice that for Payne Field (about 15 miles north of me) the temperature hasn't broken 75 all year.

Right now, (9:15 AM) it is 66 degrees inside and 60 degrees outside. At least the sun is shining which is more than we had for most of yesterday.

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