Dr. Vaibhav Chaturvedi was invited for delivering a guest lecture for the Energy, Environment and Policy course (a PhD level course) at Indian Institute of Management (IIM) Ahmedabad. The course has been designed and is managed by Prof. P R Shukla (Public Systems area, IIM Ahmedabad). The focus of the session was Energy-Economy-Environment modeling, with a special focus on applications of the Global Change Assessment Model (GCAM) for India. For the first part of the class, Vaibhav established the basic understanding of modeling in general, the qualitative aspects of modeling, and the important differences between statistical models like regression and the class of integrated assessment models like GCAM which focus on the long term energy-environment scenarios. This was followed by a detailed discussion on a specific modeling application within the GCAM framework, namely the modeling of building energy services' demand and consequent energy consumption. This included discussion on how to involve the technical as well as economic aspects within a model. The discussion summarized the building sector energy modeling paper published in Energy Policy by Dr. Chaturvedi, Prof. Shukla and other co-authors. The final part of the session browsed over some other research publications focusing on modeling applications of GCAM namely analysis of technology targets approach for the Indian power generation sector, and importance of end use energy efficiency in long term energy and emission scenarios. The class concluded with highlights related to some important differences between top-down models like GCAM and bottom up models like MARKAL, and the role all these models play in energy-environment research.