I am modeling a supermarket for a LEED project and in the model I have some refrigerated and freezer rooms that at the moment we are leaving unconditioned so that the HVAC system doesnt apply any loads to that area.

For those areas, should I just make them a different thermal zone or make them a shell that butts up to the building and has the adiabatic walls?

Not sure what the best way to do this is.

Also, on my proposed building, we are having a HVAC unit just serving the perimeter of the core retail area that has all the refrigerated cases.  I know that I have to make a seperate shell and place it off to the side, I will end up just making it have that area zone but do I put all the loads in it as well or just copy the shell and just assign the other HVAC system to it and leave the loads empty since they are addressed in the original shell?