This Report presents a comprehensive study on the design of sandwich composite panels for passive building roofs, focusing on achieving both structural integrity and energy efficiency. The current work focused on various core materials, such as foam, honeycomb, and thermal insulation capabilities of Ultra light materials, Polystyrene and Water Glass composite. Further discussions are aligned to address the "Integrated Sandwich Composite Material “Finally, the work is summarized with brief of Mechanical Performance (Core design specially), Thermal Insulation and Energy Efficiency of Sandwich Structure.