The economic analysis for running two kinds of hybrid air conditioning systems: all-air and air-and-water, both with add-on evaporative cooling stages, is studied in this paper. Single-duct, single-zone, constant volume systems are dealt with. Processing the climatic data of the European ＇test reference year-TRY for Italy, a comparison of such systems＇ performance versus the relative traditional one is performed. Energy consumption and operating costs are evaluated by an appropriate computer code written with the aim of: (i) making plain the input/output of data; and (ii) displaying very friendly software masks as well as useful graphical elaboration. On the basis of outdoor air state, calculations are performed according to two different procedures: (a) hourly, following the TRY profile; and (b) for each bin, 1 degrees C wide, in which the simultaneous dry- and wet-bulb temperatures fall.