A zonal model is a new kind of numerical model to simulate the airflow and temperature distribution within a room by means of personal computers. It is an intermediate model between multizone and Computational Fluid Dynamics (CFD) model. Compared to multizone models, zonal models can provide engineers with an estimated view of airflow and temperature distribution within a room. which cannot be predicted by multizone models. Zonal models have advantages over CFD models in their simple use. time-saving characteristics and satisfactory precision.  In this thesis, a thorough review of zonal models is presented. Based on the review work. the development of a new zonal model. P[barbelow]ressurized zO[barbelow]nal M[barbelow]odel with A[barbelow]ir diffusers ( POMA ), for the analysis of airflow and temperature distribution within a room was proposed. POMA model overcomes some limitations of the previous zonal models.  There are two kinds of ventilation situations. i.e. natural and forced ventilation, which POMA can handle. In the forced ventilation, to specify the supply airflow conditions. a new method which takes advantage of the existing diffuser characteristic equations was proposed. This method is proven to be applicable.  POMA was applied to four case studies in two kinds of ventilation strategies, i.e. natural ventilation and forced ventilation. POMA's predictions were then compared with measurements and/or Computational Fluid Dynamics (CFD) model predictions. A good agreement between the predictions of POMA and CFD model and/or measurement results demonstrates POMA is a practical tool for the analysis of airflow and temperature distribution within a room.