Two recent methods for the fast simulation of the building airflow are studied: the fast fluid dynamics (FFD) algorithm and the use of graphic processing unit (GPU) for scientific computing in building engineering. A GOOGLE SketchUp plug-in for the FFD program was also developed as a model-creating tool to enhance the accessibility of the operation and to extend the range of users. The new methods are verified to be much faster than conventional computational fluid dynamics (CFD) models and they can achieve real-time simulations. This thesis focuses on the applications of the FFD program to illustrate its functions and abilities. The application fields include but not limited to fast building airflow analysis, architectural design and urban planning associated with airflows. Although the results are not as accurate as the conventional CFD, it is designed for the needs of fast simulations and analysis with less requirement of accuracy. With further improvements in the future, the developed FFD program in this study can become an important tool to bring the engineering analysis of building simulation into the early stage of the architectural designs.