Topography integration to wind downscaling

In building energy simulations, an urban context is assessed for its impact on local wind conditions. This process, known as wind downscaling, generally considers terrain that is characterized by the obstructions such as buildings and trees. However, topography, the shape of a land, is hardly considered for its combined impact with terrain. Wind downscaling is particularly challenging in large urban areas for the required high computational costs, while the existing models are still in their infancy. This paper developed a method to integrate the topography effect in existing terrain-driven wind downscaling. To facilitate its utility in early design stages, sampling and interpolation approach were adopted for computational efficiency. Samples were generated for urban contexts, considering topography with slopes and terrain with buildings. These samples were geometrically modeled and assessed for outdoor wind speed in virtual wind tunnel tests with CFD simulations. The assessment results were analyzed and stored in a database, which was used to interpolate for a new condition. The proposed method was demonstrated for its reasonable accuracy and high computational efficiency by comparing the interpolation result with CFD simulation for an actual site.