Modern buildings in particular are very well-insulated so that as little heat as possible is lost when heating. This also means that no air exchange with the outside air can take place. Fresh outside air has a range of positive properties, not just for the building, but also your health. Fresh and healthy air improves your concentration and contributes to better physical wellbeing in general. Regular room ventilation also reduces the impurities and pollutants in the air. In a worst-case scenario, these can lead to diseases. Anyone who is not able to ventilate correctly, or forgets to do so, will have to deal with the formation of mould on the window and in the apartment. This cannot just be damaging to your health, it also takes a great amount of time and effort to remove. And it is often associated with high financial costs. Correct housing ventilation can prevent this moisture and save costs. Besides this, room ventilation is a preventive measures to combat the development or onset of allergies. If pollen, dust or cat hair remains in the room air for too long due to a lack of regular air exchange, the risk of an allergy attack for persons suffering from allergies is significantly higher.