The purpose of this study is to analyze the changes in the thermal environment of commercial areas due to changes in floor area ratio and number of floors. The Sewoon Redevelopment Promotion Plan was selected as the target area, and nine cases with changes in building floor area ratio and floor area were selected. Finally, the wind environment, thermal environment, and comfort were evaluated using Envi-met, a microclimate analysis model, for the nine cases. The implications of this study are as follows: First, we conducted a simulation analysis of changes in the urban thermal environment according to floor area ratio in commercial areas, which are high-density development areas, to derive a floor area ratio that can alleviate the urban heat island phenomenon in commercial areas. Second, we analyzed the impact of the proposed changes to the Sewoon Redevelopment Promotion Plan on the urban thermal environment.