Energy efficient functional retrofitting of buildings helps in reducing the energy and resource consumption of a building. This translates into cost benefits which are achieved during the operational phase of the building in post-retrofit scenario. However, the net benefit received has to be analysed by considering the entire life cycle of the building. Hence, this paper investigates the actual cost benefits achieved and its impact on the financial viability of an energy efficient functional retrofitting project, by analysing actual cases of functional retrofitting of buildings (for achieving greater operational efficiency) in Indian context. Cost analysis in this study includes the parameters of net present value, internal rate of return, payback period, and equivalent annual cost for comparing the considered cases for post-retrofit scenarios of building. The results are then correlated to the initial cost of functional retrofitting for each case in order to identify the inter-relationship and trend with respect to the level of intervention opted for the cases.