Windows and shading devices occupy an essential part between inside and outside environment of buildings, for providing interior air quality and optimization of lighting and HVAC energy consumption. This paper aims to perform the thermal performance of double pane Electrochromic window (ECW) using Finite Element Method and the energy performance using the Building Information Modelling (BIM) tool. The thermal model of the ECW is simulated in COMSOL Multiphysics. Double pane glass with and without electrochromic (EC) layer is analyzed to obtain the average and maximum surface temperature between the top and bottom layers of the glazing. It is observed that the maximum temperature gradient is observed with EC layer. The energy performance with a double glazing and ECW for warm and humid climate is evaluated using eQUEST DOE tool. A 30 % reduction is observed in the annual energy consumption with an ECW compared to that with a double-glazing window. In addition, during the monthly evaluation of energy consumption, there is 10% reduction with the ECW compared to baseline. The appreciable thermal characteristics and the energy performance of the EC glazing proves it to be an alternative solution for normal window glazing in automated buildings for thermal comfort and lesser cooling load demand.