Cold. Keep it cold, cold, cold.
You cold? Buy a sweater.
Us perpetually warm (yeah, I know, I sound fat. I'll cop to "could lose a few pounds", but I'm really just one of those dudes who's never, ever, cold) guys can't exactly shed a layer of skin.
Plus it makes the computers less likely to overheat. 😛
Ever try typing code all day while your fingers are so cold they significantly hurt?