When a stack in industrial facilities is not sufficiently high compared to the surrounding buildings, the dispersion of discharged pollutants can be affected by the buildings; this is commonly termed as building downwash. To enable more precise prediction of the building downwash, we have developed a computational fluid dynamics model that can reproduce momentum plume-rise process. We confirmed that the most of the surface concentrations predicted using the proposed model are within a factor of two of the wind-tunnel experimental results. Our study suggests that the mesh types around a stack can affects the prediction of surface concentration in high wind speed conditions.