As an adaptation measure to hot environments, this study proposes a cooling method that stores water inside a moisture permeable waterproof designed in a bag shape and promotes evaporation from its surface. In this study, panel made of a moisture permeable waterproof membrane was set under a tent, and experiments were conducted to verify its heat mitigation effects. On a sunny day in summer, it was found the panel surface temperature decreased by about 7 degrees due to evaporation, and the glove temperature under a tent decreased by about 0.5 degrees. © 2022 Architectural Institute of Japan. All rights reserved.