Ludwik asked about wetting the walls of a house to help cool it.
This summer was so hot in Northwestern Ohio that I tried several things, including hosing down the wall of my house. My house is a large brick Victorian style. The walls are three-bricks thick with air space between each layer. I have a lot of thermal mass and I thought the sun was heating up the bricks during the day and then the bricks slowly lost the heat at night... too slowly.
I took a digital thermometer and tried to measure the surface temperature of the bricks, but also could probe into a small hole to find the temperature in the middle of the first brick, and also the temperature in the first air gap. Then I hosed down the wall, waited a while, and remeasured. I was hoping evaporative cooling would significantly cool the bricks from the day's sun.
I found that hosing down the wall only lowered the brick temperature a couple degrees. The evening I did it the west wall started at 98 degrees about an inch into the outer brick. The sun was almost down and behind trees, and the air temperature was about 90. I hosed down the wall and waited an hour. At this time the air temperature was about 87. The brick temperature at the same spot was 94 degrees. In another area that I did not wet, the bricks had cooled from 98 to 96 over the same period. Therefore the water helped, but not much.
I think the problem was humidity. An hour after wetting the wall the bricks were still damp. I believe the humidity was so high, and the breeze was so slight, that I just wasn't getting much evaporative cooling.
When the temperature is high, the humidity is high, and there is little or no breeze... there isn't much that works other than good-old AC.
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817