In this report, we estimates the potential of heat island mitigation strategies in Keihanshin district area by using numerical model. As a result, it is found that heat load reduction of an artificial exhaust heat origin is effective at night and that of an earth surface origin is effective during daytime. Furthermore, we examined how the heat load changes when evaluate with the weighted environmental heat load method which is explained in report NO.2. Quantity of heat mitigation load was evaluated to be large when the influence of temperature is strong. Thus, weighted heat load evaluation was shown to be useful as an index to describe the influence of temperature.