This paper describes results of the experiment and the numerical simulation in order to grasp power-saving effect of indirect cooling of the outer unit of air conditioner with rainwater in summer. Followings are findings. 1) In a case rainwater spraying onto the humidification element set at the suction of the outer unit, the outlet temperature of the compressor was decreased at 6 oC lower than without spraying at most. Electric power use of the air conditioner, thereby, was declined in 15 % at most. 2) Saturation efficiency of the humidification element is estimated at 0.78 and much larger than dry mist’s 0.3 ~ 0.5.
