The effect of 3-dimensional replacement of urban activity was discussed in terms of thermal environment on the basis of numerical simulation with a mesoscale climate model. As for the 3-dimensional replacement of urban activity, concentration decreased the surface air temperature. The concentration is apparently effective for the thermal environment in the daytime, while the reduction of energy consumption is effective in the nighttime. And through sensitivity analysis, it shows that building width, height is important for the environment of the ground level.
The results of this study are summarized as follows;
1) The impact of anthropogenic heat is dominant in the nighttime and the impact of land use is dominant in the daytime.
2) As for the 3-dimensional replacement of urban activity, concentration decreased the surface air temperature. The reason was the exhaust height of anthropogenic heat became higher and the influence around near surface layers became smaller.
3) The 3-dimensional replacement of urban activity, especially concentration is apparently effective for the thermal environment in the daytime. On the other hand, the reduction of energy consumption is relatively effective in the nighttime. Therefore, the combination of these two policy options is available.
4) Decreasing building width shows temperature increasing and wind decreasing, and that means small but tall pencil building is one of the factors of heat island compared from wide building.