The scientific monograph is devoted to the sustainable development of energy systems. Energy supply is a unified system that includes not only manufacturers but also management systems and consumers. Scientific monograph includes energy system researches, analysis and modeling of their operation not only at the level of a single system but also a variety of heating and power system element level. The monograph includes three main chapters summarizing the evaluation and simulation methods for analyzing energy systems development and operation. The first chapter shows the range of use of the system dynamics model. In the second chapter, using sustainability, assessment models, the sustainability of energy systems is evaluated from both the resources and the sector’s user side. In the third chapter, energy sector action is analyzed and evaluated using engineering models. The monograph summarizes the results of the IESE to evaluate and simulate the operation of power systems. Monograph is relevant not only among scientists and industry professionals, but also people involved in the development of the national economy.