Computational Fluid Dynamics (CFD) and ECOTECT have been employed to model the mechanical and natural ventilation of a semi-transparent photovoltaics integrated airflow window and the daylighting impact of various PV transparent degrees (0.15, 0.2, 0.25, 0.3 and 0.35) on the interior space, respectively, for winter conditions noon time in London. This paper presents results of modelling of the airflow window system integrated with an office room for energy efficiency and adequate level of thermal and optical comfort. Results have revealed that buoyancy induced flow spreads the heat internally warming the space to be thermally acceptable during the heating seasons. The thermal and visual comfort was compared for different PV airflow window transparent levels to determine the optimum PV transparency for the office space. It has been found that a PV transparency of about 0.2 and 0.25 are optimal for the indoor comfort.