Let me explain, what I mean, you take a 12" PVC pive or duct out of the top of the highest point of the room e.g. in a vaulted ceiling, and take it outside and bary the pipe/duct 4 feet undergound where it is always around 55 degrees Fahrenheit and bring it back in the room in a low point with or without a fan build-in, after the hot air cools down from 80-95 F down to 55 F, saving you a bundle on AC costs.
This is not a new Concept: the bedouin in the desert of Saudi Arabie have been using this for over a 1000 years
It’s an interesting question. While I acknowledge the historical basis and that the principle is sound, I can see some issues with your approach.
PVC pipe isn’t a very good heat exchange material. You can tell this by running hot water through a PVC pipe - it takes a while for the heat to transmit through the pipe wall.
A 12" diameter pipe has a very low heat exchange surface area per volume of air transmitted, tiny compared for example to a heat exchanger in an AC unit, or to an underground cave or passage providing cool air to a tent or residence. I think you’d have difficulty achieving even a noticeable drop in temperature.
