The heat island is caused by 2 factors. One is a change of the urban land use, and the other is human activities like energy consumption. In this study, the authors quantified the contribution of urban land use and human activities to the heat island and evaluated the impact of land use's change and human activities' change on urban climate. Numerical simulations were practiced in the 23 wards of Tokyo Metropolis. The results are shown as follows;
The effect of anthropogenic heat on the urban surface temperature is around 1.5°C in summer and 2.5°C in winter at the most. And the urban land use effects around 1°C in both seasons.
If 20% of the whole building area turns into the park, the surface temperature will decrease around 0.5°C, and if into the water, around 1°C at the most.
If 100% of the anthropogenic heat for cooling use is decreased, the surface temperature will decrease around 0.5°C at the most.