In order to evaluate the amelioration of urban heat island effects with latent heat flux from green roofs, the pond was installed on a building roof. Evapotranspiration rate in summer was estimated with the observation of water level fluctuation and precipitation. Over the 76 days study, total precipitation was 142 mm and the evapotranspiration from water was 361 mm with additional 204.0 mm irrigation. Accumulated latent heat flux for the duration was corresponded 78 % of total solar radiation. To evaluate the effects of aquatic plants on evapotranspiration, weighing experiments with and without aquatic plants of the water container were carried out. Evapotranspiration rate from aquatic plants were greater than that of bare water container. So water surface covered with aquatic plants have more efficacy than water surface for reducing the urban heat island effects with relative small area.
