An evaporative cooler is used to lower the temperature and increase the humidity of the air by using the latent heat of evaporation, changing a liquid to water vapors. Warm dry air is changed to cool moist air. The heat of outside air is used to evaporate water. Evaporative air coolers can be used indoors, but only in the places where there is a hot dry environment. The use of an indoor evaporative cooler helps to keep your home environment comfortable & cool. These coolers are not recommended to be used indoor in a humid climate. Fresh air is required to use it indoor.