Due to a bad power condition in bihar i have tested an old traditional thing.
Just mop your floor with cold water and let it dry. take a thin cotton cloth, dip it in cold water and squeeze it well. put it on floor and let your dog sleep on it... he will feel better in this awful summer :) you can remove the cloth if you feel its uncomfortable for your dog.
this works for me during long power outs hope this will help you too...
tested by me and mishka :) Good luck