The manual gives ideas about the composition of the air and the parameters of its condition; features of microclimate in ship premises, design air parameters and their rationing, heat and humidity balance of ship premises are considered; provides information on the construction of a diagram I - d of humid air and the reflection of the processes of heat and moisture treatment of air on it; concepts of ship systems providing microclimate of ship premises are described. The textbook is written for students of the day, evening and correspondence departments of the shipbuilding faculty of the State Technical University, studying the discipline "General Ship Systems."