Hey guys I'm new to the forums, Can anyone give me some information on earth tubes? Thanks

"Earth cooling tubes present an alternative for controlling temperature within residential and office buildings as well as greenhouses and other structures requiring temperature regulation. These tubes run underground and alter air's cooling or heating temperature before it is allowed into a home or office. En route, the air releases its heat to the surrounding soil so it becomes cool air when it reaches its target structure. If the soil surrounding the tubes is warmer than the air within, the air acquires heat so it becomes warm air when it reaches its target."

source = http://www.tech-faq.com/earth-cooling-tubes.shtml

I have used earth tubes and I think it is critical that the tubes be sloped for drainage.  Also be sure to protect the ends at grade with mesh to keep critters away.  In some applications without grade being available I have seen the tubes protrude above the earth and then turn 90° so rain will not enter.  My only concern for this type is that of moisture building up in the tubes.  I have seen one building that had water in the ductwork that was below grade.  Water could facilitate the growth of mold.

Alton,
I have been interested earth tubes for many years, but have never used them. The condensation factor here in the south has always been an issue in my mind, as well. I have always assumed that some type of sloping to daylight, to allow for drainage, would be necessary. Aside from this issue, what are your experiences with earth tubes? How well do they work in our climate?
I have also considered tieing the earth tubes to a box surrounding the outdoor compressor unit of an electric heat pump system, to stablize the temperature of the air used in its heating and cooling cycles.  Any thoughts about that hairbrained idea?

New guy here and enjoy all the info.

Is this setup different enough from the earth tube to work in a humid environment?

http://mb-soft.com/solar/saving.html

It's basically (if I understand it correctly) a closed system of underground pipes where the air is blown through and cooled off before it returns to the inside of the house.

Jonathan