I recently received an email in which a man asked about using bales when building underground, as in an earth-bermed house. He wants to use bales due to their high insulation value, but is concerned about the effects of moisture on the bales. I too would be concerned about the moisture. We are trying to figure out a way to make it work as it would be a great marriage for sure!
I suggested that if he could find a way to use a material that would provide a break between the bales and the backfill, it may be possible. In other words, he would need to place the backfill against a structural element (what is yet to be determined, but perhaps concrete and a plastic waterproof membrane?) that would provide the strength and protection from ground moisture. He could then stack bales (the back side pre dipped in plaster for fire protection) slightly away from that wall so to leave a ventilation channel between the bales and the backfill assembly. That channel may need mechanical help in providing adequate air movement to protect the bales from moisture.
Seems a bit over the top to me, but I would like to see what other options you may have for such a job. I would really like to see this as a possibility in the future. Thanks for any input you are willing to share.