A As a tropical country the ventilation system has long been applied in Indonesia, thiscan be seen from the ventilation design of traditional buildings in Indonesia.Inserting the wind continuously into the room as a process of changing the air cancool and provide air comfort in the room. In addition, with the presence of airmovement that directly touches our skin, can help the process of evaporation insweat, compared to areas with cold climates and subtropical climates, thermalcomfort in humid tropical climates has different benchmarks, namely the presence ofsweat factors. So that the level of wetness due to sweat can be one of the benchmarksin determining thermal comfort. In humid tropical climate conditions, the design ofthe louver window openings is used to be able to ward off radiation and the flow ofair circulation in a room. This research was conducted to look at the relationshipbetween the window window design variables to the air velocity in space. There are 8louver window design variables, namely the angle of the blades, the width of theblades, the thickness of the blades, the distance between the blades, the shape of theblades, the direction of the blades, the position of the blades, and the fields on thewindow. The dependent variable based on the object of research is influenced bydesign variables, namely the velocity of air in space. There are 3 dependentvariables, namely the maximum speed on the floor plan, the maximum speed at theappearance of the pieces, and the average speed. The object of this research is thewindow louver in a room measuring 3x3x3 meters. There are 120 sample windowblinds with different air speeds. The results of the study show that thickness in theblinds of window blades affects air circulation in space rather than other designvariables.