So I thought I would close the loop on this question/discussion. The best you can do with my use case is 2 pistons. The first piston being used to calculate the average temperature and save it to a global variable. And then the second piston has several triggers with individual actions. And with the way the triggers are setup only one can possibly be true when the average temperature changes.
House - Calc Avg Temp
House Fans - Auto-Adjust
I tried getting it down to one piston but that isn’t possible because variables (global or local) aren’t available to later conditions within the same piston.