3 ms·
And these are one of the more reliable sensors. Be aware of other sensors that print out a TVOC or even HCHO (formaldehyde) value but really only measure CO2.
by mkesper 2y ago
And these are one of the more reliable sensors. Be aware of other sensors that print out a TVOC or even HCHO (formaldehyde) value but really only measure CO2.
- wkat4242 2y agoUh no it's the opposite. Measuring TVOC is really cheap, a couple bucks for a sensor. Measuring CO2 directly is really expensive (about 50 bucks) using either lasers (still the most accurate method) or a complex ultrasound method that Sensirion pioneered. What is happening is that some CO2 sensors are actually "eCO2" (estimated CO2) and estimate the value based on the TVOC. Which is really just a guesstimate because the two have no direct relation. It's just a presumption that low TVOC means that fresh air has recently entered. And formaldehyde is a subset of TVOC. It makes sense to measure it separately because it is emitted a lot by cheap furniture and fabrics and is one of the more dangerous compounds. TVOC sensors also react super heavily to alcohol so just spraying a bit of perfume causes it to jump skyhigh for hours.
- t0mas88 2y agoI use a Sensirion CO2 sensor for automatic home ventilation. It works well, because ventilation is more about the relative levels of CO2 and rate of change. I'm not sure the exact value as reported by the sensor is very accurate. TVOC sensors are indeed useless. They measure so much noise that you can't use the data for anything.