This paper explores an approach based on a systematic-integrated modeling framework which helps to investigate the optimal behavior of an urban energy system. The model allows us to: 1) analyze the impacts of various demographic scenarios, 2) test and evaluate different policy measures for deploying patterns of efficient use of energy resources and emissions mitigation in the system and 3) test technological and system level solutions such as centralized versus decentralized energy supply networks. A highly resolved optimization technique using mathematical programming is applied to identify the cost-effective measures for achieving specific energy and emissions reduction-targets. The model then is applied to identify the optimal energy flow from available energy resources (Fossil, Renewable and external sources) to the end-user level in selected cities of Asia.