We're restoring a barn here in maine and building a living space in part of it. The apartment is 12x28, two floors. It sits on an 8" insulated slab with tubing 12' on center. The exterior walls will be framed on the outside of the posts and beams to expose them inside the living space,we're using spray foam for these. The 28' wall is a south facing wall with plenty of windows. The north wall is inside the barn and will be insulated with cellulose and rigid insulation. East and west walls will have spray foam. We're heating the radiant floor with 4 4x10 solar water panels with wood boiler to back it up. The second floor ceiling will be well insulated. We were thinking of installing radiant floor heating in the second floor but someone stopped by and asked if it was really needed. What do you think? Any suggestions would be appreciated.