Building envelope system consists of five elements. Below Grade, Exterior Walls, Fenestration, Roofs and Atria. The building envelope system has to design to achieve performance requirements like Thermal Performance, Moisture Protection, Fire Safety, Acoustics, Day Lighting, Perimeter Visual Environment, System Maintainability, Material Durability. The envelope system also has to often design to resist Seismic Actions, Blast, Extreme Wind, Flood, Indoor Air Quality and Mould Prevention. Modern focus on sustainable construction and zero carbon foot print demands integration of sustainability, energy conservation and energy creation into façade design. In addition to meet this larger number of façade requirements, the diversity of environment and climate at different parts of the world makes façade design complex and challenging.