In the present article, the flow field and passive gaseous pollutant dispersion in a naturally cross- ventilated isolated single-zone model building have been investigated. The large eddy simulation (LES) approach has been applied together with three different sub-grid scale (SGS) models, namely, wal-adapting local eddy-viscosity (WALE), dynamic Smagorinsky-Lily model (DSLM), and standard Smagorinsky-Lilly model (SSLM). The flow and passive scalar concentration fields have been compared with available experimental data. It is demonstrated that the three SGS models predict similar flow field. Also, it can be observed that the mean concentration field results obtained from the WALE sub-grid scale (SGS) model are in better agreement with the experimental data than those of DSLM and SSLM by about 8％ and 5％, respectively. Moreover, the CPU time required for the computations by the WALE and SSLM models was almost 20％ less than that of DSLM, making WALE a more suitable SGS model than the other two models for the prediction of flow and concentration fields in an isolated building. Furthermore, contributions of convective flux and turbulent diffusion flux to the pollutant transportation have been studied. It has been shown that although the convective flux is the main mechanism, the two fluxes have a significant influence on pollutant transportation and distribution.