Free Indoor Climate Guidebook (PDF)

Most of our time we live in closed rooms. Bedroom, office and school buildings are the most used rooms. For this reason, air quality is of great interest!

Grab your free copy of our indoor air climate guide ebook!

Mold, Humidity, and CO2

We spend most of our time indoors. Bedrooms, offices and school buildings are the longest-used rooms.For this reason, it is recommended to pay particular attention to a healthy indoor climate. Whether we feel comfortable in a room depends not only on the structural conditions and personal emotions of the climatic conditions in the room.

What actually causes the humidity?

Already when breathing, the human body releases water into the air. In addition, the moisture comes from cooking, bathing, showering, drying, etc. In a four-person family, an average of 10 liters of water is produced every day! In order to transport this water from interior spaces, several cubic meters of air must be moved daily.

What happens when windows, mirrors, walls, furniture condense?

If warm ambient air with a high water vapor content reaches a cold wall, the air cools in this region and consequently cannot store as much water vapor. The excess moisture must be added to the environment, i.e to its walls, its furniture, etc. Be given. Caution - there is a risk of mold damage. Ensure that you monitor these critical points with a bluSensor® AIR device.

How do I get the humidity from the room?

Air can absorb different amounts of water vapor depending on the temperature. Cool air absorbs less water vapor than warm air. Preferably:

Fresh air in - heat up - ventilate again

Cold outside air, which gets into the room when it is ventilated, heats up and can therefore absorb more air humidity. In order to remove as much moisture as possible from the room, they should be ventilated several times a day.

Shutters or cross-ventilation is the best type of window ventilation.

Cross-ventilation: 2 - 5 minutes

Shots: 5 - 10 minutes

The duration of the ventilation in order to achieve air exchange is strongly dependent on the outside temperature. The colder it is outside, the shorter they have to air.


The bluSensor® AIR app, in the free version, has an integrated timer, which calculates the optimum ventilation time depending on the outside temperature and alerts you when this time has elapsed so that they do not waste heating costs unnecessarily.

Caution - Moisture in the room penetrates into your furniture and walls!

Instant airing is by far the most effective. Make it a habit immediately after showering, bathing, cooking or floor washing to ventilate and before using the rooms to close the doors. These should only be opened again after the ventilation process. Thus, the humid air reaches the outside best, does not enter into furniture and walls and does not spread in the other rooms.

Why not leave the windows in the bedroom tilted?

With this type of ventilation, the windows often remain open for an extended period of time and the walls and furniture cool down. Especially in exposed corners, the temperature is often colder and the humidity condenses on the wall. If the dew point temperature is fallen below, the air condenses in these areas and there is a risk of mold formation.

After you get up, you can air your bedroom best. This makes you fit for the day and expels the moisture that has accumulated in the air, furniture and plaster overnight. Before going to sleep, let go and ventilate again to reduce the carbon dioxide in the room to a minimum. This ensures a good night's sleep.

Tired in the head - ventilate every 2 hours!

An increased concentration of carbon dioxide and other substances can lead to fatigue, weakness in concentration and headache. It is now known that in air-tight, modern buildings this value can rapidly rise to a critical level.

Fear of contagion - ventilation helps!

CO2 is an indicator of indoor air quality. Where there is a lot of CO2, many illnesses are found. According to an American study, it was assessed how high the risk of influenza contagion is in a 30-person classroom. If the CO2 content is in the normal range (for example, 1000 ppm), five more people were infected with influenza. At twice as high CO2 content, 12 were already present, and a third had 15 persons. If they think that a threefold normal value is certainly never reached with them, they are deceiving themselves. This COs rise is achieved with the window closed after 6 hours (assumption 16m2 bedroom with 2 persons)