This paper presents a numerical study of the coupled airflow and thermal environment in asemi-enclosed space surrounded by buildings. Our numerical simulation couples the heat transfercalculation and the computational fluid dynamic (CFD) airflow simulation in which a RNG(renormalization-group) k-? model is used. Both the solar radiation and building/ground thermal storagewere considered in the heat transfer part. The heat transfer model needs the convective heat transferinformation given by CFD and at the same time it can also provide surface temperature as the thermalboundary condition for CFD simulations. Through this model, the heat transfer and airflow behaviors inthe buildings and the surrounding environment can be investigated. In addition, the effects of differentbuilding/ground materials were analyzed through the coupled airflow and thermal model. It is found thatthe building/ground thermal mass and its thermal properties can have significant influences on thethermal environment around the buildings. The results can provide some guidance on improvingthermal environment, air flow information, and as well as the urban design and building plan forarchitects and building engineers.