The metal will reflect sunlight better than other materials.Then thermal energy more transfer through roofing. However, if you want to reduce thermal energy. You can install the insulations under your roofing.

          1. Microfiber
          2. Polynum Insulation Material
          3. Aluminium Foil
          4. Polyethylene Sheet
          5. Polyurethane Foam

          Each insulations have the different counter thermal energy efficiency and differnt suitable. You can consult the suppliers.