Method for reducing humidity in a housing

The invention relates to a method for reducing air humidity in a housing (2), wherein compressed air (10) is expanded in the housing (2). By means of this method, it is possible in a simple manner to operate a component (1) in a dry environment, to dry it, and to reliably prevent condensation on this component (1). The introduction of drying agents is thus no longer required. Furthermore, the invention relates to a drying device which comprises a component to be dried, as well as a vehicle (3), in particular a rail vehicle (31), which uses the method for reducing air humidity by means of expanding compressed air (10) for the drying and for the prevention of condensation on electrical, electronic or mechanical components (1), such as power semiconductors (11).