Poor panting Seiji Brown! All the auracanas, the buff orpingtons, and especially the light brahmas certainly struggle in the heat with their extra plummage. To further help the birds, we utilize a bit of water and "swamp cooler" technique.
Folks from the Southwest will be familiar with the use of coolers that run water over a blower in order to circulate cool air. We use the same principle in the chicken run to try to help cool the chickens down in the run.
I will set up a circular or misting sprinkler in the chicken run, and usually turn this on for a few minutes every 30 - 60 minutes. If there is any wind at all, this helps circuluate more cool air through out the run. It also cools the largest thermal mass the chickens have to deal with, which is simply the ground (more about this later).
One other variation of a home made swamp cooler for a chicken run is to take a wet cotton sheet, and throw this over one side of a fence for your chicken run. As the breeze blows through this, it will cool the air. Likewise, if placed strategically, you can also provide additional shade for your flock.
For us here in the Pacifc Northwest, these techniques work reasonably well. If you are in a region struggling with drought, or high humidity, these techniques may not work quite as well, or might require modification to reduce the amount of water you use.