This study attempts to use Overall Thermal Transfer Value (OTTV) as a performance criteria other than the Energy Performance Index (EPI). The EPI only shows the energy use index of that building, but it lacks the ability to define which factors in the building are leading to higher energy consumption. OTTV directly talks about the thermal performance of the building envelope. It provides huge opportunity to play with wall construction and window material, envelope design, WWR, building orientation, etc. to provide the most efficient building envelope with minimal costs.