I use racks from RB. They have three inch flex watt. My collection is in my basement that I am in the process of finishing. The basement has base board heating for the winter months. In the summer I need to have a fan running the circulate the air. I do not have the room set to a specific temp. The rack hold their temp and humidity just fine for me. Actual the basement is warmer then upstairs. I guess that is from the racks. I use cypress mulch as a substrate and it holds the humidity very well.