Indoor Climate


In order for a house to be confortable, it's important, that  the temperature stays within a small range, as well as the air humidity. If the air is to dry, the mucous membrane will dry up. One the other hand if the air is to wet, it's possible that the wall will start to harvest mold.


Rel. Air Humidity


The air is able to store a definitive quantity of water. If the maximum water is in the air, the air is full saturated with water and the rel humidity is 100% rH (rel. humidity). 

At 100 %rF and 20°C the absolute water content in the air is approx. 16 g/m³ 

At 100 %rF and 20°C the absolute water content in the air is approx.  5 g/m³ 

If a air with 20°C and 30% rH will be cooled to 10°C, the rel humídity rises up to approx. 100%. 

If this air is cooled below 10°C, water falls out, the air gets foggy or e.g. the window gets wet. 

The temperature, where the air reaches 100%rH is called dew point.

If cold fresh air with 0°C, 50% rH is heated to 20°C the rel. humidity gets less to approx. 20%. The humidity rises up again through people, animals or plants in the room.


The danger of getting moldy walls is high, especially at edges where the surface temperature is near to the dewpoint or less. This causes a high humidity at the wall surface and it's possible that the wall gets moldy.


To prevent mould there are 2 important points:

  1. The isolation of the wall must be very good, to prevent that the inside wall temperature comes near or below to the dew point. 
  2. through periodical vetilation the rel. humidity stays at a low level.

Our moisture measuring instruments makes  it'spossible to analzye this parameters:

With the material moisture meter AD4A it's possible to measure the material moisture in the walls, a rising material moisture can be detected. 

With the rel. air humidity sensors LFLT20  it's possible to measure the rel. humidity and the air temperature, the dew point is calculated from the masured values.

With the surface temperature sensor WT7 the wll temperature can be measured. If the wall temperature is below the dew point, moisture and mould will be produced.