Several competitive standards have been introduced, which define smart city's development framework, architecture and components or city's key performance indicators. However, these standards have not introduced specifications for smart services, nor for policy making process modelling, although standardization assists in achieving process automation by introducing "best practices" as standard process models. Policy making mainly follow non-standardized procedures, even if it is supported by various typical methodologies (i.e., Multi-Criteria Decision Methods (MCDM)). This paper is inspired by the Task-Based Modelling method (TBM) and focuses on policy making process standardization for smart cities. More specifically, in introduces a TBM schema for policy making regarding city's energy efficiency, which an important smart city aspect. This TBM is based on the outcomes of the case-study of the Integrative Smart City Planning (InSmart) coordination action in the smart city of Trikala, Greece.