That looks interesting... Might be the way to go if they could be cast on site.

Tom,
I checked into ICFs and discovered they would more than double the cost. Polysteel and just about all the other manufactures require they be purchased thru their dealers. Most I found to be a little sleezy.

Regarding the thermal conductivity... I believe I might benefit by NOT having the wall insulated. The ground temp here at the depth I'm at remains fairly constant. If the wall stays dry then it will be a good bit of geothermal mass. May just have to dehumidify to keep the condensation down on the warm moist days.

Here's a pic of the hole. It about four times this size now.

And, one of many loads of rock being hauled.

Just beyond the trees in the background is the drop off to the valley. Next tall ridge is maybe three miles with nothing but trees, pasture, a running stream and a few cows in between.

Attached Thumbnails