I am trying to figure out some costs to build a large refrigerated building.

What I'm most curious about is the actual design of the building? I want to do R35-R38 to keep refrigeration costs down.

Anyway, here are my basic dumb questions:

Why do they do insulated panels as opposed to just straight insulation? Can I take an EPS foam block, some eps spray, and some liquid nails to create the shell (inside the shell of the building)?

Or why do they do the panels as opposed to a BATT insulation in the wall and blown insulation on top?

Should the ground be insulated? How much will I lose through that? I'm only looking to keep the building to 43F (in TX).

I'm got more but my brain is fried for today.

Thanks,
Jon