In this thesis the value engineering is applied to the casing of an upgrading air-conditioning system of a passenger train. On the basis of the definition of the major functions and the setting of the function analysis it was possible to identify and analyse the main costs through various methods (e.g. ABC analysis). While applying the gallery method and the brainstorming method the thesis develops solutions for these functions. In the next step new solution variations were combined in a morphological box. Finally, in the course of a utility-analysis and an economical observation the thesis presents more cost-efficient solutions for the case of the air-conditioning system.