Why do we need dehumidification?

The need for efficient dehumidification is not just relevant in connection with water damage, construction work, production processes, swimming pools, waterworks and other obviously damp areas. Buildings, valuables and people in all sorts of climates will often benefit from dehumidification in less obvious everyday situations.

The outdoor air is never completely dry anywhere in the world, and indoors multiple sources add to the relative humidity of the indoor air: transpiration from people; steam from cooking and bathing; humidity emanating from production processes or the storage of damp goods; even building materials and furniture slowly drying out add to the overall humidity of a room.

Due to ever-rising energy prices, buildings of today are much better insulated than before. While keeping out the cold, the insulation also reduces the air change and traps humidity. A sure sign is dew on windows. That can easily turn into moisture causing damage to the woodwork.

Download our “Selection guide for mobile dehumidifiers” for professional guidance on how mobile dehumidifiers work and how you choose the right one for your project.

The main reasons and signs showing that dehumidification is needed:

  • Mould and fungus attacks
  • Conditions favourable to microorganisms
  • Metal surfaces becoming unpaintable
  • Electronic equipment malfunctioning
  • Corrosion attack
  • Moisture damages on goods, building parts, furniture, etc.
  • Discomfort due to humid indoor climate

In all these instances, lowering the relative air humidity is required. This can be done in a number of different ways. On a hot dry summer’s day in Denmark with a room temperature of 20°C and 60% RH (relative humidity), the content of water in the air is approximately 8.5 g water/kg air. In an 80 m3 room, this amounts to close to 1 litre water. If the temperature at night drops to 0°C, more than 50% of the water content in the air will condense as dew. That equals 5 g water/kg air or close to half a litre of condensed water in an 80 m3 room. This could cause all sorts of serious problems.

Heating and ventilation

The longest known method for reducing humidity is based on the physical fact that warm air is capable of holding more moisture than cold air. In practice, fresh air is drawn into the room and heated up so it can absorb more water. Followingly, the then humid air is ventilated out of the room. This process continues until reaching the desired conditions in the room.

This drying method based on heating and ventilation is used less and less because it is a very energy-consuming and uneconomic solution. Heat is – literally – thrown out the window. Furthermore, the air drawn into the room also contains a certain level of relative humidity. That prolongs the drying process depending on the time of year, the outside temperature and weather conditions.

Combined with the high energy prices of modern day, this has made dehumidification the preferred drying method across the planet.


The basic principle of dehumidification assumes that the room is closed. Windows and doors are closed and no, or at least very little, outside air enters the room. The air is continuously circulated through the dehumidifier, and gradually the humidity is condensed into a water container with no resulting heat loss to the outside. Quite the opposite of the traditional method of heating and ventilation.

In addition to the obvious advantages of a reduced energy consumption, the dehumidification process is much easier to control as long as the room stays closed.


Advantages of condense drying

  • Reduced energy consumption (approximately 80% reduction compared to traditional heating and ventilation)
  • Less risk of surface drying cavitations and critical point drying because the temperature is lower
  • No energy loss. The electrical energy led to the compressor and fan motor is converted into heat
  • Controllable process as the room is closed

Download our “Selection guide for mobile dehumidifiers” for professional guidance on how mobile dehumidifiers work and how you choose the right one for your project.

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