I live in the Caribbean and during the hottest evenings the temperature is around 86 degrees. We use conventional air con in the bedroom set at 80 degrees. The air temperature in the ceiling is much higher than ground level. If we created a natural air flow by having an air vent in the ceiling to allow the hot air to escape and we replaced that air via an air grid buried underground, then cooler air would replace the hot air. There would be no need for a fan to assist this and it could circulate 24/7. We would keep all windows closed. Has anyone built such a system? It would need perhaps 200 ft of buried pipe with an air intake from a shaded cool area

  • What do you plan to do to control the incoming latent load (i.e. moisture in the incoming outside air)? You don't want it condensing in the tubes, because then you get a science experiment down there... Feb 12, 2021 at 0:41
  • I did not think of that. Could holes be drilled in the underground pipes with a soak away beneath the pipes Feb 12, 2021 at 1:19
  • Holes in the underground pipe would let condensation out, however they would also quickly clog with dirt unless precautions are taken, and could allow bugs and other small critters into the piping. Search here for "French drain" to see the precautions necessary to prevent your perforated pipe from clogging with dirt. Also, natural convection may do the job admirably, but be prepared to add a fan to assist with air flow if necessary.
    – FreeMan
    Feb 12, 2021 at 12:11
  • Thank you for your comments Feb 12, 2021 at 15:20
  • I know folks that use a similar idea but in reverse for heat. They have a “sun room” on the side of the house with 4’ of rock to hold heat and use that at night so if set up right it should help.
    – Ed Beal
    Feb 12, 2021 at 15:51


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