The fact is that the most important plus of the double -glazed window, namely, its thermal insulation, in a combination of circumstances, turns very quickly and into the main minus. In other words, tightness, which is achieved thanks to a multi -chamber profile, is the cause of constant heat and stuffiness in the apartment. This problem arises quite seriously in the summer, when closed plastic windows (exactly as open) create a vacuum in the room, in which oxygen is very quickly consumed and carbon dioxide is formed. This situation reduces the performance of people and leads to a constant feeling of drowsiness. You will need vacuum equipment.