BME280 - Area Coverage
Answer
4/26/19 3:26 AM

Hi,

I have recently encountered an enquiry regarding the application of XDK / CISS Sensor.

One of the MEMS installed in these sensors is the BME280 for Humidity and Ambient Temperature.

The technical data provided some information below:

Operation range (full accuracy) Pressure: 300...1100 hPa
Temperature: -40…85°C
Humidity sensor
Response time (τ63%)
Accuracy tolerance
Hysteresis

1 s
± 3 % relative humidity
≤ 2 % relative humidity

 

What about the coverage area that these each of these sensors can measure accurately?

If the space of a room is for example 5m x 5m, how many sensors do we need in order to get an all-round accurate measurement?

 

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RE: BME280 - Area Coverage
Answer
4/26/19 9:22 AM as a reply to Ahmad Khairi Hamzah.

Hi Ahmad,

The XDK actually outputs what happens in the immediate vicinity of the device. If you want to measure a room with different humidities and temperatures, you should know how and where you want to measure.

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RE: BME280 - Area Coverage
Answer
4/27/19 12:27 PM as a reply to Saeid Kajlar.
Hi Ahmad,

I have run an ambient monitoring setup based on the BME280 in a similarely sized room as a mold alert monitor and I am quite happy about the long-term monitoring results I had over a full year.

So short answer is that one sensor is sufficient for your 25m2 room.

The long answer depends on the physics and your expectation.
Here please take into account
  • the position of the sensor in the room (measurability)
    (it should be central or at least 15cm away from a wall and some distance from humidity producing bodies like humans, animals or plants and also should have a larger distance from heating elements).
  • the airflow inside the room. Forced airflow towards the sensor improves the response
  • Temperature differences inside the room and the sensor itself. Self-heating of the XDK110 due to wireless activity, battery charging influences the result a lot!

Also take into account that humidity and temperature have a slow response and reaction time due to physical effects (diffusion, thermal transfer, thermodynamics! and fluid-mechanics!). It  takes a lot of time (like 30min) for a such a sensor to react to a fast change. An adecuate measurign time interval might be 1s - 10min for industrial applications and 1min - 1h for domestic applications. 

Regards,

Francisco

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