The Central Business District (CBD) of Ahmedabad in India, planned to be developed by 2040, will have increased floor space, three times of what it is in 2020. This will double the cooling energy demand if contemporary practices are followed. This research aims to develop building envelop retrofit strategies which minimize the lifecycle cost and the total annual cooling energy consumption in the coming decades, till 2040 with a rise in floorspace for the CBD of Ahmedabad. For this, an Urban Building Energy Model (UBEM) of 0.7 km² of the CBD, is developed for 2020, 2030 & 2040 using the existing dataset available with Ahmedabad’s local government. A multi-objective cost vs energy optimization is performed using the modeFRONTIER software coupled with the EnergyPlus simulation engine for 2020, and the savings are projected till 2040. Five envelope properties including glazing solar heat gain coefficient (SHGC), wall and roof insulation and roof’s solar absorptance are selected for the parametric study with a range of values prescribed within the augmented stringency of the Energy Conservation Building Code of India (BEE 2017). A Design of Experiments (DOE) developed by the Uniform Latin Hypercube (ULH) is performed with 90 iterations on all the buildings. To minimize computational efforts, a Response Surface Model (RSM) based virtual optimization is carried out. The sensitivity analysis indicated that the SHGC of the building’s glazing contributes to 70% of the total cooling energy consumption, followed by roof absorptance and insulation. Thus, shading the windows and applying a high reflectance roof paint are the most cost-effective strategies. With the selected set of envelope configurations, there is a potential reduction of 30% in the total cooling energy consumption of the CBD for 2020.