Top positive review
5.0 out of 5 starsOutstanding - much better than chemical based sensors
Reviewed in the United States on March 4, 2024
I bought this INKBIRD CO2 sensor because it uses the NDIR measurement technique, which should be much more accurate than an older sensor I had been using. The older unit seen in the photos uses a chemical method that is temperature sensitive and drifts in value tremendously. I have been using the INKBIRD now for a couple weeks and it does not appear to have any drift or accuracy issues. I love it.
Pros
1. The calibration from the factory appears very good. It measured 430 ppm or so both outside and near a fresh-air intake system I put together for house ventilation. I don't plan on doing any calibration of the unit myself. The value of this NDIR based system is that it should not need periodic cal like my old unit.
2. The values I get for my indoor CO2 are typically in the 600's, which is consistent with what I would expect for our house size, occupancy, and energy efficiency.
3. The unit responds well and reasonably quickly to increases in CO2 due to occupied closed rooms (or inside/outside air switching in car). And if I breath near it (don't breath on it!), I have seen it shoot up to 1500 and recover in a couple/few minutes. Exactly what it should do.
4. The screen is beautiful of course. And the case sits nicely anywhere you put it.
5. The other measurements (temperature, humidity, and air pressure) are good too. HOWEVER, the original cal on humidity seemed to be off by about +10% -- at least relative to two other sensors I trust. FORTUNATELY this was an easy fix through the app. You can just tell it to add or subtract an offset to bring it back to where it should be. Now it tracks the other units well.
Cons:
1. The app is generally nice, and works, but it is a bit unpolished. They should have their developers use the product more to catch things like this: It seems to re-download numbers from the unit all the time. This takes a fair amount of time once you've been using it for several weeks. Also, the scaling of the graphs defaults to just the last few measurements. You can pinch the screen on the phone to rescale it - but why should I have to do this every time? (Yeah - I can live with this considering how well the unit itself works. But a better default behavior like showing the full time-period would be so much better for the user)
2. I had to add a -10 offset to get the humidity readings 'correct'. (See 'pros' above)
3. Air pressure is not displayed on the unit. That's OK really - just worth noting. You have to use the app for that.
4. Response time is kinda slow for temperature. The fastest update rate is 1 per minute (configurable through the app). And the CO2 and humidity numbers retrieved seem to have a response time on the order of a few minutes - which is very good. But the temperature sensor must be mounted to the board/case because it takes on the order of an hour for it to settle to the new value when moved to a new location at a new temp.
Summary: I got this on sale and at the 99 dollars I paid for it, it is amazing. It is also excellent at the full price. It is a real measurement instrument, unlike the old "Air quality monitor" box I had been using which drifted more than 300 ppm over an hour or two, so that it was nearly unusable. In contrast, this AIRBIRD NDIR-based sensor/unit is excellent. No regrets at all. I might even buy another one. (It's nice and portable, so I can take it to places I spend time in to gauge how good their air-exchange rates are :-) )