Evaporative Air Cooler is a positive pressure ventilation system device that have the ability to cools air through the evaporation of water. Different from typical air conditioning systems, water evaporative cooling uses water to absorb a relatively large amount of heat from dry buld in order to evaporate.The temperature in dry buld (Dry air in the ambiance) can be dropped significantly through the phase transition from liquid water to water vapor (gas / steam). This can cool air with much less energy compare to typical refrigeration system, but with certain temperature limitation (lowest at water temperature at particular ambiance condition).