Humidity definition: understanding causes and effects

Water exists in three forms: gaseous (steam), liquid, or solid (ice). In the ambient air, it is present in the form of water vapor, at varying concentrations. We then talk about Humidity in the air, a central concept in many fields: construction, meteorology, well-being, etc.

When the vapour concentration reaches a maximum threshold (called Saturation point), it is transformed into liquid water. That's what we call the condensing. This phenomenon is the cause of many humidity problems in buildings.

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Relative and absolute humidity: what is the difference?

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The Relative humidity is expressed as a percentage: it indicates the quantity of water vapor present in the air compared to the maximum quantity that the air can contain at a given temperature.

The absolute humidity, on the other hand, measures the real quantity of water vapor (in grams per m³). These two indicators are complementary and make it possible to better understand the humidity level in an environment.

Example: at 20°C, if the air contains 10 g/m³ of water vapor and can contain a maximum of 20 g/m³, the relative humidity is 50%.

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Condensation and visible humidity: what are the consequences?

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When the water vapor condenses, it forms liquid water on cold surfaces: windows, walls, ceilings. This may result in:

• Of traces of humidity or mold
  
  
• Degradation of materials
  
  
• An unhealthy environment
  

This phenomenon is often referred to as “humidity” in everyday speech.

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How do I detect and measure humidity?

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Humidity can be unseen but have important consequences. Here are some tools to measure it:

• Humidity meter or professional humidity tester
  
  
• Humidity sensors integrated into buildings or weather stations
  
  
• Humidity tester to monitor room humidity
  

In case of doubt, it is recommended to measure the humidity level to avoid structural damage.

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How to avoid humidity and condensation?

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To prevent the effects of humidity, several solutions exist:

• Regular ventilation of the rooms
  
  
• Effective thermal insulation
  
  
• Use of a dehumidifier Or of a moisture absorber
• Pose of dehumidifier bags (silica gel, etc.)
  

In case of recurrent condensation, it may be useful to calculate the dew point to better anticipate risks.

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In summary: what to remember

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• Humidity is the presence of water vapor in the air.
  
  
• It can become liquid through condensation.
  
  
• It is measured in Relative or absolute.
  
  
• It has visible consequences in buildings.
  

There are solutions for control humidity effectively.