Google translates as: s a new Ruuvi user, I find myself noticing and wondering about all sorts of things. One thing that caught my attention was the VOC index: right from the start—when I took the sensor out of the box and placed it on the table—the average reading was around 50.
It sat there for about a week, and then the graph shows the index dropping rapidly to a level of 36; after that, it began a steady rise, and the level is now just under 100.
So, my question is: did the sensor calibrate itself during that drop, establishing the current conditions as the “new normal,” or what could be causing the rise in the level? The device is in a cottage that has been unoccupied for the better part of the last two weeks. There haven’t been any radical changes in the prevailing conditions, either; the maintenance heating has remained at the same level, and so on.
How does the sensor calibrate, and how often does it happen?
Marko replied: Ruuvi Air’s VOC index measurements use a 7-day “learning period,” meaning the moving average becomes more precise during that time. On this scale, 100 represents the “normal” level. We will soon be publishing a support article addressing these questions
Great! Thanks for the reply, @marko. It’s certainly interesting to track how the readings develop. The sensors are really precise.
I’ve purchased the Air and am waiting for it to arrive.
What exactly does it mean that “100 is the so-called normal on this scale”? I’m just wondering: if an apartment has a high baseline VOC level (say, a new build) and I start up the Air in that space for the first time and leave it there, won’t it calibrate itself to that prevailing “normal”—which is actually an unhealthy level?
Thanks. I forgot to mention that I had already read your documentation, which is why I’m asking.
Based on the statement "Remember during setup that the index requires a 7-day learning period to establish a reliable baseline," I gather the answer is that the sensor calibrates itself to the prevailing environmental level at that time. In other words, if the VOC level is consistently high, that level is defined as the "baseline" (100), and if the sensor is moved to a space where levels are lower than that index, the reading changes. Have I understood this correctly? If so, the instructions could certainly explain this in greater detail and more clearly.
Thank you for the clarification and the good point. The principle is understood correctly here.
The SEN66 VOC index is a relative metric: it learns the environment's typical VOC background and sets it as a baseline of approximately 100. If the background level remains high for an extended period, the algorithm may adapt to it. When the sensor is moved to a cleaner environment, the index may drop below 100 and adjust to the new level over time.
It is therefore a matter of adaptation rather than actual calibration. Thank you also for the feedback—it would be good to state this more clearly in the instructions.