Among all building envelops, windows are typically the weakest barrier to heat ingress. The building energy consumption of any conditioned building located in the tropical country is deeply governed by the amount of heat gain inside the building because heating ventilation and air-conditioning (HVAC) system is a major energy consumer. Hence, it can be easily inferred that the energy consumption of a building can be reduced through judicial selection of window glasses. This paper illustrated the importance of thermal transmittance (U-value) and solar heat gain coefficient (SHGC) value of window glazing in detail and also demonstrated the energy savings potential of various types of commercially available windowpanes. The electric energy savings potential of various types of windowpanes such as tinted, reflective, single glazing, and double glazing glasses have been analyzed through eQUEST energy simulation software for a building, situated in the tropical region of India. Building architectural data and all other information regarding HVAC, lighting, etc. have been collected during the energy audit and trained in the eQUEST simulation for further analysis. The calibration of simulation model has been done using actual monthly electricity consumption data of the case building. This study depicts the percentage decrease in electrical energy consumption due to retrofitting of various commercially available window glasses compared with base building. The study also compares the importance of main two determining factor(s) U and SHGC value behind the judicial selection of proper window glazing.