Radiant Barrier Insulation

When we put up a pole barn with a metal roof I used 1" rigid foam insulation 4' x 8' sheets under the metal, with the mylar side down. really keeps the heat from radiating down, and is quiet in a rainstorm. Now that the horses are gone I closed it in for my shop, metal siding, plywood interior and lots of windows. Stays pretty comfortable temp-wise here in FL.