Switchable exhaust air insulation (SEAI) window is an airflow window with venetian blinds in-between the glass panes. A simplified heat transfer model is developed for evaluating the thermal performance of window based on energy balance over the glass panes and flowing air. To validate the model, the simulation results are compared with the results of zonal approach. The influence of airflow rate and incident solar radiation on the accuracy of model has been carried out. Results demonstrate that the proposed model has enough accuracy and is a relatively simple method for evaluating the thermal performance of the SEAI window.