The need and the demand to save expensive energy means that apartments and houses are becoming more and more “air-tight” with modern windows and doors, which means that users, moisture-enriched air is hardly replaced by fresh air.
Since humans and animals continuously release moisture into the room air and consume oxygen, the relative humidity increases in the dense rooms, and the air quality deteriorates. Especially in the bathroom and in the kitchen, the humidity can take high values. For example, each person releases up to one liter of water overnight while sleeping. Also, through existing house plants, the humidity is increased.
What does “relative humidity” mean?
The relative humidity is the ratio of actually contained to the maximum possible mass of water vapor in the air.
The relative humidity is also called a saturation degree.
The maximum possible amount of water (in the form of water vapor) that the air can absorb depends on the temperature.
One cubic meter of air can absorb about the following amount of water and is then 100% saturated:
|– 7 ° C||->||2.2g of water|
|0 ° C||->||4.4g of water|
|+ 10 ° C||->||8.8g of water|
|+ 15 ° C||->||11.0g of water|
|+ 20 ° C||->||17.0g of water|
|+ 23 ° C||->||20.0g of water|
How can the humidity be measured?
There are several physical ways to measure humidity:
- The dew point method:
Here is z. B. a mirror is cooled in the air until water is deposited on it. The temperature difference between mirror temperature and air temperature is a measure of the humidity.
The ball of a liquid thermometer is wrapped in a damp cloth. Due to the evaporative cooling, the displayed temperature drops. A second and “dry” thermometer indicates the ambient temperature. The difference between the two displayed values is a measure of the relative humidity. (Can then be read from the “psychrometric table.”)
- Hair hygrometer: With hygroscopic substances (hair, plastics), the length changes with the moisture. The hygrometers based on the show the relative humidity after calibration.
- Absorption method:
Hygroscopic substances remove water vapor from the air. By weighing, the absolute humidity of the room from which the steam has been extracted can be determined.
For the private household, mechanical and electronic hygrometers are available on the market.
Comfortable and frequently encountered are the electronic weather stations, which, in addition to the temperature, immediately display the indoor and outdoor humidity as well as additional weather values.
When are there any problems with the humidity in the living room?
Humidity problems are expected when there are cooler spots compared to room temperature, and the air is enriched with moisture. Especially in the corners to outer walls is often due to the presence of cold bridges, a lower surface temperature. Since the moisture-enriched air must release the excess moisture when cooled, the steam condenses in the cool place. It forms dew; the wall becomes moist.
These problems often occur in homes in winter when the outside walls are cold. In summer, high humidity problems tend to occur in basements in colder areas.
A damp wall has worse thermal insulation values. If it is moist, it cools even more at low outdoor temperatures, the effect described above increases.
On the damp wall, paint, paste, and wallpaper create ideal conditions for the growth of harmful mold or fungi.
If mold is already present, it manifests itself as a musty, musty odor or through first dark spots.
Effects of the white horse on humans
The mold releases spores and metabolic products into the room air. These are inhaled and can cause allergic and irritating reactions in humans.
The following symptoms may occur: a runny nose, sneezing, coughing, headache, tiredness, red eyes, rash, conjunctivitis, throat, and nose irritation.
How can damp walls and mold be prevented?
- By the right temperature choice!
Care must be taken in the rooms to ensure a sufficient minimum temperature so that the outer walls cannot cool down too much (not below 15 ° C).
Condensation is thus avoided.
20 ° C, bathroom: 21 ° C, bedroom 18 ° C during the day, 15-16 ° C at night).
- By the right humidity!
The relative humidity should not be over 65-70% in the long run.
Recommendation: If a value of approx. 50% is maintained at a room temperature of 20 ° C; it can be assumed that even in unfavorable places where the surface temperature is approx. 13 ° C, no moisture damage is to be expected.
- Through proper ventilation!
Especially in winter: Regular short airing (about 5 minutes); Here, the moist air is replaced with dry air (controlled by the hygrometer) or controlled ventilation by a ventilation system.
- By correctly placing the furniture: place
furniture a few centimeters away from the outside walls, so that the warm room air can repaint the outer wall. (Especially important in new buildings, which are not completely dried out.) Also, beware of pictures on exterior walls; Use spacers to allow air to circulate behind the image. Built-in furniture on exterior walls should be avoided, especially in older houses!
- A handy measure against damp interior walls is the attachment of thermal insulation on the outer walls. This is especially useful for a future renovation or new construction. Here heat losses through the wall are reduced. The wall is almost at room temperature, which also raises the dew point temperature. Moist corners and mold are avoided. Also, enormous heating energy and thus, costs are saved.
Ventilation units with heat exchangers are recommended.
Also recommended is the installation of ventilation systems that ensure a continuous exchange of air. The heart of the system is a heat exchanger that removes the heat energy from the used air and supplies it to the cooler fresh air again. The heat recovery is up to 90 percent. So when airing no high power is “burned” into the open, but remains in the living room.
Smaller appliances, so-called decentralized ventilation units, which can be retrofitted to ventilate a room, are also available on the market.
Central ventilation units are only located in one room and are connected to the places via a pipe system. This variant is suitable for new buildings. With these devices, it is also possible to use a geothermal heat exchanger, which preheats from the outside sucked cold fresh air in winter (or cools warm air in the summer), thereby saving additional energy and increases the comfort in the house even further.
With all these devices, continuous air exchange is guaranteed – the danger of mold formation is almost excluded. Also, the sense of wellbeing naturally increases due to the presence of fresh, oxygen-containing air.