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KNX ADVANCED COURSE

Figure 66: CO 2 concentration sensor

Figure 67: A typical Group Object in ETS for reading the current CO 2 concentration value

6.3.3 Humidity sensor

A humidity sensor, which consists of a thermometer and a hygrometer, measures
temperature and humidity and calculates the dew point. Actually, humidity measurement
determines the amount of water vapor present in a gas. This can be a gas mixture, such
as air, or a pure gas, such as nitrogen or argon. The amount of water vapor in air can
affect human comfort as well as many industrial manufacturing processes. The presence
of water vapor also influences various physical, chemical, and biological processes.
Humidity measurement in industry is critical because it may affect the business cost of the
product and the health and safety of the staff. Hence, humidity sensing is very important,
especially in control systems for industrial processes and for ensuring human comfort. For
domestic applications, humidity control is used to ensure proper living environment in
buildings and to indicate moisture levels in the environment.
The KNX humidity sensors can also receive external measured values via the bus and
process them with own data to calculate an overall temperature and air humidity (mixed
values).

Figure 68: Humidity sensors for indoor and outdoor use

The humidity value is measured and expressed in percentage and is transmitted using a 2
byte Group Object with encoding 9.007, DPT_Value_Humidity, which has a resolution of
0,01 %.

Figure 69: A typical Group Object in ETS for reading the current value of the humidity

Home and Building Management Systems KNX Association
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