Interesting stuff. We have about 13' x 14' room which is currently an indoor pool until the roof is on and the room is pumped out. It is 11' under ground which translates to 55 degrees year round. I will put HVAC in it just in case I need it, but the room is surrounded by a water tight wall, plus 8" block.

We'll have a chilly tasting room down there so guests will not want to hang too long! It's like the guest bedrooms, we want the spikes to emerge on the third evening used so they know it is time to go bye-bye. lol

Thanks for the link. I sent it to the builder.

John