# How you can avoid measurement errors

Just like temperature, humidity is best measured in the middle of a room. Additionally, the humidity can be recorded in the corners of the room, behind cupboards or similar, which should be separately noted in the report.

Even just opening the door, or being present in the room for a longer period, changes the air humidity in the room. For this reason, the following applies: enter the room quickly, close the doors and perform the measurement promptly.

In humidity probes, the humidity in the air must first "diffuse" into the plastic layer of the probe. The duration of the acclimatization time is critically dependent on how well the air circulates around the sensor. It is shortened if the probe is moved in the air.

### Influence of temperature

A typical situation

The measurement case is transported at 0 °C ambient temperature during the winter. At the measurement site, the measuring instrument enters a room with 20 °C and 50 %RH.

What happens?

Condensation forms on the humidity probe: In the "micro-climate" of the probe at 0 °C, the saturation of the air is max. 4.8 g/m3. However, the air in the room contains approx. 9 g/m3. of humidity.

The right way to measure

Move the probe at 1.5 m/s smoothly from the wrist. The "breaks up" the "micro-climate" (0 °C) surrounding the probe, and the actual room climate of 20 °C and 50 %RH reaches the sensor.

#### Influence of measurer

A typical situation

When adjusting the measuring instrument, the probe comes ibnto contact with the user's breath.

What happens?

By breathing on the probe with humidity-saturated breath, the relative humidity (%RH) in the measurement surroundings of the measuring instrument increases, and with it the temperature.

The right way to measure

Hold the humidity measuring instrument at arm's length as far as possible from your mouth, and move it smoothly from the wrist at approx. 1.5 m/s.

### The right measurement location

A typical situation

At 25 °C, a humidity content of 50 % relative humidity is determined in the middle of the room. In the same room, at 15 °C the measuring instrument shows a relative humidity of 90 % close to the wall. Which value is correct?

The right way to measure

Just like temperature, humidity is best measured in the middle of the room at a height of 1.1 m. If you move the probe only slightly or not a at all, you must calculate an acclimataization time of ten minutes into your measurement.

### Avoiding measurement errors: All tips at a glance

• Measure in the middle of the room.
• Measure at chest height.