The goal of the present doctoral thesis is the development and research of the recommendations and applied methods for an optimal control system of the passenger compartment’s heating, ventilation and air conditioning (HVAC) units in public transport, increasing the train passengers’ comfort level, and taking into account the necessity of reducing electric energy consumption. The review of available literature and publications about the topic researched in the doctoral thesis is provided in the introduction of the thesis. The first chapter of the thesis offers the formulation of the research target describes the topicality of the theme and defines the objectives attainable within the research framework. The second chapter of the thesis specifies information about the research object an environment of train passenger compartments, their characteristic and affecting factors, about the characteristic parameters of passenger comfort and their defining standards. The present chapter offers information about the power unit of the HVAC equipment - the construction of heaters, air conditioners and air handlers and about their characteristic parameters. The third chapter of the thesis elaborates the theoretical aspects of the applied intellectual control methods and their role in the HVAC units’ management, as well as discusses their possible application in the control system. The fourth chapter of the thesis describes a control implementation of the developed HVAC system, provides a diagram of the control system and a control algorithm, and offers the author’s vision of an exploitation of the wireless technologies in running of the system. The fifth chapter of the thesis carries out an experimental test of the developed system and a computer modelling of the most important units of the HVAC control system, as well as it describes the process of modelling and experimentation, the equipment and computer programmes used, and the results obtained from the experiment. The analysis of the conducted research is carried out in the conclusion of the thesis. Effectiveness and usefulness of the methods applied, usability of the developed control diagram in the HVAC system control, as well as an influence of the applied control methods on the electrical energy consumption and passenger comfort level are analysed. The doctoral thesis is written in the Latvian language on 121 pages, which involve 114 pictures and diagrams, 6 tables, as well as the references to 151 literary sources and 26 author’s publications, and it has 2 appendices on 50 pages.