Influence of natural ventilation on solar gains and natural lighting by opening windows

Natural ventilation generally implies a complete or partial opening of windows which modifies the solar gains and the natural lighting, changing the solar and daylight factors. This “secondary” effect is generally neglected in building energy simulation. This study analyzes the impact on the modification of optical characteristics of glazed surfaces on thermal condition and natural lighting due to opening windows. The results focus on the impact of window opening on visual and thermal performance including not only the air change rate but also the negative effect of solar gains which arrive directly in the room through the opening. The parametric study leads to conclude when this effect can be neglected or not.