We’re renovating a 25 x 40 building with unheated slab in northern Vermont.  The slab is mostly below grade.  We plan to build a floor above the slab and install radiant heat using climate panels in 2/3 of the space and leave the remaining area unfinished and unheated.  

Will there be a problem with the portion of the slab that will remain cold while the other part will have a bit of heat as a result of the radiant tubing?  

One suggestion was to cut the concrete between the 2 areas and install a thermal break.  

Thank you for your ideas.