I have used the frozen milk jugs since I read about it here, and it seemed to help. I half fill 2 jugs and freeze them and leave them in the run (day) or roost area (night) to emit coolness. I also have had a fan on constantly for the last month. I live in Bethlehem PA and we have had a hot, humid summer so far, with days in the 90s several at a time. I also let mine out in the AM and when I get home, and they have a tarp over their run. They use their dust bath area like crazy in the heat. I love the sprinkler idea, i have tried to hose them but they hate it, and their roost is high in the coop and when they pant I have misted them there (they all seem to dislike it but I figure it's cooling them), but now i will try the sprinkler the next hot day, good thought! I am so sorry you lost any, I didn't know we had to worry about that until reading about people losing them to heat, it's heart breaking. I have 9 Buff Orpingtons and 1 barred rock and 1 Golden Comet (awesome breed) so these are not small birds, especially the Buffs. Oh, I also insulated my coop! I think that definitely helps in the heat and the cold!
Good luck,
Shelagh M.