By regularly ventilating, you bring fresh air into your indoor rooms and ensure that air humidity, evaporating pollutants from furniture, carpets or chemical cleaning agents or other annoying odours such as tobacco smoke escape to the outside. Only when there is sufficient oxygen in the room do people and pets feel comfortable and perform well. In addition to health, factors such as legal principles play a major role. Tenants are obliged to provide adequate ventilation. If they do not comply with this obligation, tenants can be held liable for any damage and defects such as mould. To ensure that proper ventilation is successful, we clarify the most important questions about ventilation.
Is continuous ventilation good?
Proper ventilation depends strongly on the duration. But "more" is not better. This is about the removal of air humidity. However, continuous ventilation with a tilted window cannot guarantee the necessary air exchange. Especially if the temperatures inside and outside the room differ greatly. For example, the fresh winter air contains less moisture than the indoor air. It does not matter whether it is raining or snowing. The difference in temperature makes it difficult to exchange moisture. Continuous ventilation also wastes heating energy, causes the window reveals to cool down and promotes mould growth.
How do I ventilate properly at home?
Mistakes often happen when airing. For reasons of comfort, for example, the windows are only opened a crack and then they remain in the tilt position for quite a while. When the windows are tilted, however, there is little air exchange. Most of the time, the room only cools down and heating costs rise. However, this does not create a pleasant room climate. The right way to ventilate is to open the windows wide so that the air circulates in the room. Also remember to move any curtains to the side. The effect is greater this way. The more effective the air exchange, the sooner you can close the windows again.
How long do you have to ventilate?
It is better to ventilate several times a day than to ventilate continuously. Ideally, you should open several opposite windows at the same time. The resulting draught transports the stale air out of the rooms more quickly. Also adapt your ventilation behaviour to the season. Our seasonal recommendation for the duration of ventilation:
- December to February: approx. 5 minutes
- March and November: approx. 10 minutes
- April and September: approx. 15 minutes
- May and October: approx. 20 minutes
- June to August: approx. 30 minutes
In both April and September, the combination of temperature and humidity favours a faster exchange of air than in the adjacent months.
Can mould develop due to too much ventilation?
Due to modern construction methods and energy-efficient modernisation, buildings are becoming increasingly insulated. Air exchange through cracks and diffusion of moisture through the walls no longer works. If the humidity does not escape to the outside, there is a risk of mould and moisture damage to the building fabric. Mould spores and pollutants in the indoor air can lead to respiratory problems and allergies . If the mould spores exceed limit values, rooms are uninhabitable for health reasons. Therefore, you should observe the air humidity as an indicator of mould growth.
Tip: You can find out how to detect and even prevent a possible mould infestation on the basis of the air components in our extra blog post.
Especially continuous ventilation with tilted windows creates so-called cold bridges. At these cold bridges, heat escapes to the outside much faster than in neighbouring building components. This is a weak point in the thermal insulation. A tilted window favours energy and heat loss due to the lower temperature of the immediate surroundings. In addition, condensation is more likely to form here, which can lead to moisture problems on the masonry and thus to mould growth. If walls and ceilings cool down, there is a risk of black spots and mould.
Does airing help against viruses like Covid-19?
Ventilation is one of the most important measures during the cold season, especially to protect against covid-19 infection. After all, colds like Corona are transmitted through the air. Here, the viruses attach themselves to aerosols, small particles in the air, and thus spread throughout the room. By removing the stale room air contaminated with pathogens and exchanging it for fresh air, you significantly reduce the risk of infection indoors .
A high concentration of carbon dioxide (CO2) is an unmistakable indication that there are particularly many germs and aerosols in the room air. This is how a study by scientists shows the risk of infection during influenza. During the test period, 30 people were in a classroom for four hours. One of the people was suffering from acute flu. The result: at 1,000 CO2 per million, five people were infected, at 2,000 ppm already twelve and at 3,000 ppm 15 people were infected. Accordingly, there is a clear connection between increasing CO2 pollution and an increased risk of infection.
Follow these ventilation tips:
- Ensure regular air exchange - especially if several people are in a smaller room. In this case, ventilate at least once an hour for 5 minutes.
- When ventilating, close the doors to adjacent rooms to prevent virus exchange through draughts.
- Ventilate according to the situation: If someone coughs or sneezes, open the windows briefly.
- Keep an eye on the CO2 levels in the room, they are a good indicator of an increasing viral load in the air.
Poor air quality due to excessive CO2 levels
Too much carbon dioxide in the air you breathe is a risk to your health. If the air pollution increases, complaints such as malaise, lack of concentration or loss of productivity also increase. At levels as low as 1,200-1,500 ppm (parts per million), drowsiness, inattention, reduced concentration and headaches increase. The insidious thing about CO2 pollution: the symptoms already appear before you notice the high CO2 concentration in the room air.
Depending on the number of people in the room as well as the use of the room, the level of carbon dioxide increases and the quality of the air we breathe decreases considerably. However, our organism depends on oxygen to function properly. With too much CO2 in the air, your body is prevented from absorbing oxygen. Too much carbon dioxide in the indoor air has even been proven to lead to an increase in absenteeism at workplaces and in schools and daycare centres.
Measure air components & ventilate properly
Air quality is difficult to assess. Therefore, we often miss the right time to ventilate. The most important thing on the way to a good and pleasant indoor climate is the best possible ventilation strategy. Air measuring devices that measure the air components and warn us when limit values are reached provide support here. With up to 14 sensors and other calculated measured variables as well as its own health and performance index, the air-Q is by far the most comprehensive air measuring device - made in Germany. For example, it determines carbon dioxide by means of an optical sensor. The whole thing is done with so-called infrared absorption. The CO₂ molecule absorbs certain wavelengths of infrared radiation. This is also how the greenhouse effect occurs, for example, because this heat radiation cannot leave the earth. The sensor measures how high this thermal radiation is. To be really accurate, the intensity of the infrared LED is also monitored with a second measuring beam.
In addition to carbon dioxide, the air-Q evaluates the influence of other pollutants on your physical health and performance. Using the air-Q Health Index™ and the air-Q Performance Index™, you can see the composition of your indoor air both on the device and in detail via the air-Q app and web app. Based on its results, the air analyser not only tells you when it is time to ventilate. It also provides you with comprehensive assistance on how to identify sources of pollutants and thus improve the air quality.
(Cover photo: Canva/ Gal Daniel from Getty Images)
