District cooling by water source heat pump system is more effectual than by air source one, and also heat release to the air in utilizing area disappears. But the other hand, it's feared to decrease "cool island" effect of river that the river water temperature changes. In this study, at first, difference of artificial exhaust heat by cooling between cooling systems was discussed and exhaust air conditions through cooling tower or air to air heatexchanger were discussed. At last, thermal effects on atmosphere caused by district cooling utilizing river water at Tokyo area were estimated.
