I have heard that opening a basement window and some upstairs windows will create a draft in the house to cool it. To increase the flow with a "venturi" effect, would I keep the upstairs windows slightly cracked and the basement window wide open, or the reverse?
Cannot answer that question but if you have a double hung window, the best way to us it is to have both the top and bottom window open a bit. Hot air goes out the top and cool comes in the bottom.
Open them and see. But not truely. A truely effective design in a southern home of one of the first Presidents had a dome open at the top ringed at the bottom of the dome with gas pipe , when burned pulled air up through the house. Gas was cheap then and no electric fans or AC
To get a true venturi effect you'd need a tapered (cone-shaped) exhaust system. Otherwise, just open both windows the same amount and take advantage of the simple "hot air rises" principle.
The exhaust opening should be larger than the intake. Design with Climate page 112 notes, "However, the relatively low air speeds of normal rise are inadequate to achieve relief from high termpratures or to amelorate the discomfort caused by by vapor pressure conditons." My experience in a house with central stair well about 30 feet tall is negative. I raise a skylight above the stair and get some air movement, but the rooms connected to the vertical shaft don't benefit, unless windows are raised in them as well. Wind direction relative to the openings makes a big difference in the amount of air moved.
Some uesful books: Controlling Air Movement by Terry Boutet Design with Climate by Olgyay Wind in Architectural and Environmental Design by Melaragno
Tom Baker
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