It is estimated that today more than 70 % of European population lives in urban areas – cities and city suburbs. Cities are initiators of development, but, at the same time, the ones responsible for a significant part of harmful emissions. Therefore, cities represent great potential for implementation of the concept of energy sustainability, which includes reduction of energy consumption and increase of energy efficiency resulting in the reduction of harmful emissions. Smart cities are examples of both economical and energetical sustainable development of urban areas. Smart measures in energetics include, among other things, traffic solutions, smart lighting, district heating and cooling systems and integration of renewable energy sources. Within the framework of the paper smart measures in the field of energetics are listed and examples of smart communities, both in EU and Republic of Croatia are given. For five chosen measures – smart parking technology, smart lighting, district heating and cooling system with solar collectors and heat pumps, integration of PV modules and integration of electric vehicles, technical and economic analysis for the City of Zagreb was conducted. Analysis was conducted in computer program EnergyPLAN and the results were compared with the reference model based on five chosen parameters. Simulation has shown that each of the implemented measures reduces the emission of CO₂, most notably integration of electric vehicles with a reduction of 8,26 %. From the economic standpoint, integration of PV modules has been proven the best with return of investment period of 1,258 years. On the other hand, the smart parking system is characterized by great investment costs and barely visible savings. The ideal scenario would include simultaneous implementation of all measures which would result in 9,13 % reduction of CO₂ emission and 869 million € decrease of annual costs.