I didn't see this but I used to use this trick to help combat texas summer heat. Where I lived at the time there was very little breeze so cooling them off was important.
I had a large hackberry tree in my yard that grew over the coop and pen area. So, to help cool it down, not only would I spray their sand down but I would also spray the leaves of the tree. You could feel the difference in the area right around them. Sometimes, since it is so dry I would have to do it twice to three times a day but it does work.
As far as the swamp cooler method, if you don't have burlap and you need them cool asap, cut a bath towel in strips and hang the strips all around the area. They do help but not as efficiently as the burlap.
Another hot weather trick I have learned is that you can buy the dog waterers that take the 2 liter bottles. You fill a few bottles with water and freeze them. You put the frozen water bottle on the dog waterer and as it melts (which in 113 degree weather doesn't take as long as you would think) they will be supplied with nice cool water. Make sure if you use this method that you tie your bottle to the fence as invariably you will get at least one that will figure out how to sit on top of it.
