As a matter of fact I have 2 fans on the Jackson's viv. There is a computer fan built into the kitty litter wall (which is all dried out), as well as a fan that sits on top of the screen lid. The cham lives in my basement and the temps drop pretty low with the lights off at night.
Edit: Although, honestly he doesn't spend much time in his enclosure. The majority of the time he is wandering around the basement picking off spiders, chilling in his ficus tree or one of my other houseplants, or trying to catch the guppies in my paludarium through the glass (very sad to watch, I feel bad for him sometimes).