Cool room walls

It something I haven't tried myself, but I'd imagine as long as the room is "breathing well" (cycling potential stagnant air from all 8 corners of the space), and replenishing the room with fresh air frequently enough so condensation doesn't build up anywhere within the grow space.

If you can pull that off, I honestly believe that it's a material that would be hard to beat.

Go for it, they are good shit to use. I used to look after grow rooms that were refrigerated as well as heated for AQIS at their old Richmond Vic gardens. If I had the money I would replicated one in an instant. CO2 bottles stainless steel benches water piped in, the ducks guts for growing any plants.