Low tech air-conditioning

by **JohnDenver** » Mon 20 Jun 2005, 02:38:11

By accident, my apartment has this strange natural air-conditioning. I noticed it when I first moved here. Every summer when it gets hot, I just have to open the front and back windows, and an incredible draft blows through. I'm feeling it right now, and the blow rate is roughly equivalent to the medium setting on my 45 watt fan.

It blows constantly, always in the same direction, and I wondered about it for a while. The explanation seems to be this: Out back there's a black asphalt parking lot, which is usually about half full. I'm figuring that the air rises off the asphalt, creating a convection current which draws in cool air from the shaded courtyard at the front of the building.

by **jato** » Mon 20 Jun 2005, 02:56:48

You are lucky (or smart depending on how you look at it). In Phoenix Arizona right now (midnight) it is 100F.

Link

by **gnm** » Mon 20 Jun 2005, 02:57:52

sounds like a correct assesment, now if you are in a fairly dry climate just put a clothesline on the intake side and hang your wet stuff there or just a few wet towels and you can drop it another 10 degrees...
:-D

-G

Jato -ugh! I hate Phoenix, and thats one of the reasons! lesee here at 7500ft in NM its about 55F out.. :-D

by **jpfrazer** » Mon 20 Jun 2005, 04:53:11

Well spotted - its a classic, and common in vernacular architecture in the Middle East. This effect is combined to great effect with windcatchers, fountains, thermally massive walls, tall rooms and open-weave sunscreens etc to make the 50degC heat bearable.

by **Devil** » Mon 20 Jun 2005, 05:39:59

gnm wrote:sounds like a correct assesment, now if you are in a fairly dry climate just put a clothesline on the intake side and hang your wet stuff there or just a few wet towels and you can drop it another 10 degrees...

Not if the RH is high.

In any case, dry 38°C is much more bearable than humid 28°C. It is currently 34°C here with a reasonably dry 33% RH and I don't need the aircon on (office temp is currently a reasonably comfortable 31.9°C).

The human body is much more sensitive to humidity than temp. That is why the cheap evaporative "room coolers" are a scam. They may drop the temp a little, but they push up the humidity even more.

by **FoxV** » Mon 20 Jun 2005, 11:04:59

what about a water chiller. Pumping water through a second hand car radiator. Should be usefull in areas that have freezing winters were the ground water is cold (ideal in canada because most of us have a be-jesus load of water, ground water is always around 4C (40F), and a lot of us are not metered :-D

).

by **gnm** » Mon 20 Jun 2005, 12:04:02

Devil, thats why I said (if he lives in a dry climate) and sure if there is a thunderstorm going on or somesuch it won't really help... but then its usually cool anyways.
Well here we use an evaporative cooler which draws hot dry outside air through it and it cools our house really well. It can be 85 out and we can get it down to 67 inside... RH around here is often as low as 9% (get out your chapstick folks) - the nice thing is the evap cooler can be run on about 200 watts vs 2k watts for a small refrigerated air...

(That 55 number was at 1am btw)

-G

Low tech air-conditioning

Low tech air-conditioning

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