I turned a shed into a drumroom and just bought a cheap 70 dollar air conditioner and mounted it in the wall to help maintain 75 degrees all the time. Runs around 20 extra a month, but only during summer. (im in arizona)
I moved my "mini set" back to the basement and rejoined it with the other part. The basement has a constant temperature, so I need not worry anymore. Playing with a 4 piece set and 3 cymbals was cool, but got a bit boring after a while. Now I'm back to my 8 piece with 12 cymbals .