A study on natural cooling system by rainwater and underground heat with ready-made drums in a wooden experimental house is as follows. First, the temperature of rainwater before an experiment was about 15 degrees. Next, water temperature withdrew to about 16 degrees by underground heat in about 3 days after experiment. As a result of having used control of pump and tank, the room temperature maintained 24 - 29 degrees. And PMV maintained less than ±1. But, only by control of tank, we cannot continue this system.
