So, I know this question, without shade or one-story, has been answered many times on the 'net, so I have some actual physics for the one-story. I am fairly certain my roommate mixed up thermal venting. Scientifically, I'm just checking if my dispersion "forgot too many factors" like volume of air in shade, ground-to-air, etc Short Version: Check my math in the BTU paragraph. But sun/heat specifics are in whole post.

I would like my math checked, and both arguments weighed against physicists, since even though I'm on the 2nd part, my roommate is right about not having control temperature, and this is the last hot day of week, so can't measure: I also would like to know if rates of dissipation counter my argument, as far as ground conductivity.

1st half is responding to me saying "All the articles you sent require two story houses" referring to thermal vent/siphoning. He measured, the temperature increased both doors, which is what he's dismissing as needing control data.

I've pasted the raw discussion, as personal of an issue it is, both of us are pretty nerdy and stuck to the sciences. I respect him for that. But I'm burning up right now and I'd like to prevent this.

==== 1st half ====

Nope, just looked through the articles, this one being a good example.


Top comment states has windows on same side of building. We have one on a somewhat shaded area vs one window on a side exposed to the sun.

Also, as far as temp rising well that's a given considering the sun moving across the sky during the day. Rises in the NE, sets in the SW, at some point the stairway will get more sun exposure but will, for the most part have less than the south facing patio area. And of course that stairway will almost always keep that area mostly in shade.

The only way to really test the hypothesis is that we would need two days in a row that have the same temps and monitor them throughout the day, one day with closed doors, no air circulation and one without. Regardless, as I've shown air circulation will always be better than no air circulation. especially if one has entry and exit points where temps are absolutely lower in one area than the other. The front patio area and the entry shaded by the stairway aren't even close.

For your hypothesis to work re cool air blowing in and then the hot air within say a few minutes there would need to be a noticeable rise in air temp, it's remained pretty much steady for awhile now, whether on top of Tony's computer or in the kitchen. Because that hot air entering the stairway is moving very slowly with no real breeze, just natural circulation it will be cooled as long as that area remains somewhat or mostly in shade.

===== 2nd Half ======

Assuming no other windows are open, that might work.

The top comment assumes air is cooler. The replies to it also assume outside air is cooler. The fan blowing outward assumes no air intake "I reverse it to try to keep air moving in the unit without actively blowing in warm air."

The article you sent, has no disproof. Please send a different article or point to the area that actually makes things cooler.

Then there's posts on windows being open or not: https://www.google.com/search?q=open+window+in+heat&ie=utf-8&oe=utf-8

The thermal conductivity of air is 0.015 btu/ft, air gets raised temp at 0.2 btu per foot by one degree, and sunlight is 450 btu/ft on a clear day, so the heating rate of sun is over 200x times faster than the cooling rate. You're telling me the air moves through the shaded area slow enough to cool faster than the sun warms it, which is about 1/200th of a foot per second.


Summary of Question: So, is a shaded 7 by 7 ish porch enough to cool the house? And if so, should I leave that door open but the others shut, or let the breeze go through?

His reasoning is an entire wall of architecture books with some physics, mine is just physics I learned in HS. Apt is likely insulated, and facing S, sun hits sideways but does hit the wall during day - which may help.


1 Answer 1


Sometimes it's just faster to measure. Bought 2 exactly same type of thermometer, left both in wrapping. They both said same temp. Walked home 12 minutes, both ended up at above 88. Put one inside, put other in shaded area near porch, under the "tree" that gives us all the cool shade, and the stairs, and otherwise surrounded by walls, in the shade. (also on a box)

Air inside 15 minutes later, the thermometer moved down to 81 (I took video, no need to link it here). Other still at 88.

Doing this at intervals, but the initial test, buying at 2:06 and measuring at 2:21 is enough to prove the difference.

House has been closed up all day, control conditions.

Note, that the air is not circulating in the shaded area, thus is should be even cooler, but it is not.

I can sleep tonight.

I will acknowledge that breezes will always make you feel cooler, but you will heat your home insides and that heat will radiate later


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