The end wall (15) of the modular unit has a protrusion (23) with a recess (16), which with a closing element (24) of a ventilating and heating module (21) forms an air guide component (22) integrated into the end wall. The air guide component has an air duct (31) which is rectangular in cross-section. An air inlet (28) is formed in the narrow side of the protrusion and in which is integrated an air inlet grill (29). The air guide, viewed in the direction of travel, is located at least partially in front of the end wall.
