Humidify the air

If the relative humidity drops below 40% for several days, the air needs to be humidified to ensure a healthy comfortable climate. Find out more about how to optimally humidify the air and how a humidifier can help.

Ideal air humidity indoors
Causes of dry indoor air
Effects of too dry air
Humidifiers: functionality and systems
Articles about humidifying the air

Humiditiy

Ideal air humidity indoors

The ideal relative humidity indoors is 40–60 %. If the hygrometer measures a relative humidity of less than 40 % for several days, the air is too dry.

Learn more about humidity

Humidifier terminology explained simply

Humidity and health: creating the right balance with the right indoor climate

Absolute and relative humidity

Causes of dry indoor air

The cold season and the use of heating systems cause the relative humidity to drop. If the room air is too dry, viruses and bacteria remain in the air longer, as they are bound more slowly by water molecules and brought to the ground. If the value is below 40 % for several days, it is time to act.

More about the causes of too dry indoor air

The problem

Effects of too dry air

If the indoor air is permanently too dry, this leads to symptoms such as headaches, burning eyes, dry and irritated mucous membranes in the nose, dry skin, an unpleasant scratchy throat, poor sleep and an increased susceptibility to colds or flu.

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Effects of excessively dry indoor air on the body

Functionality and systems

There are different versions of humidifiers, but the function is always the same: to increase the relative humidity of the room air by bringing additional moisture into the air.

Vaporiser

The water is brought to boiling point in the device using a method similar to the one applied in a kettle, for example. Boiling the water produces hot, germ-free water vapour which is emitted by the device directly into the room. Vaporiser systems, also known as steam humidifiers, are particularly suitable for allergy sufferers. It is important for limescale to be removed regularly from vaporisers. We advise against using hard water or water from water softeners in vaporisers.

Ultrasonic nebuliser

This type of humidification system turns water into mist. An oscillating ultrasonic membrane in the nebuliser atomises the water, turning it into tiny droplets. A built-in fan in the device transports them into the air as mist which humidifies the room air. In principle, the mist emitted by the device is cold because the water inside it is also cold. This makes nebuliser systems suitable for nurseries. With this system, the process of humidification is made visible due to the mist, which is why these devices are also known as atomisers. It is particularly important for nebulisers to be cleaned and descaled regularly. Nebulisers are not suitable for use with hard water or water from a water softener.

Evaporator

The way that an evaporator works is based on the natural principle of evaporation. The humidifier filters inside the device suck up water. The indoor air is sucked in by an integrated fan which guides it through the moist humidifier filters. In the process, the air absorbs the humidity required. As it flows through, the air absorbs tiny water droplets and it is then blown out into the indoor air along with the moisture. The evaporator system has two main advantages. Firstly, evaporators are very quiet, making them the ideal choice for quiet rooms such as bedrooms or offices, for example. Secondly, overhumidification is not possible with this system as the air is only enriched with as much humidity as it needs and is able to absorb based on the current temperature. With this system, the filters need to be replaced regularly. Evaporators are particularly suitable for households with children and babies, as there is no hot water in the unit as with a vaporiser, cleaning is less intensive than with an ultrasonic nebuliser and the units are usually very quiet.

Air washer

This system is a combination of humidifier and air purifier. The principle of humidification belongs to the category of evaporator systems. The difference lies in the humidification medium used: air washers use permanently reusable plastic discs while evaporators have filters which need to be replaced regularly. Air washers are fitted with a set of discs specially designed to absorb humidity and remove particles from the air. The discs which are known as humidification discs or evaporator discs rotate in the water. A fan sucks in the dry indoor air which is guided across the rotating wet discs. Pollutants from the air such as pollen, dust or hair are deposited on the discs in the process. The set of discs continues to rotate and the particles are washed off in the water. The purified moisture still present on the clean part of the disc set is emitted into the air. With this technique, the air is not only humidified but also cleaned to remove pollutants, making air washers ideal for allergy sufferers. Regular cleaning is important in order to rinse out the water tank and remove the impurities washed from the air.