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Air quality monitors: paying more does not get you more accuracy

airgradient.com

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Re: Air quality monitors: paying more does not get you more accuracy

#111

Post by ilyt »

ahaucnx wrote: post #102
casenmgreen wrote: post #93

Earlier quoted context omitted.

I would buy a couple of these in an instant, it's exactly what I want, except it's so BIG. I want something as small as reasonably possible.

We originally designed a smaller monitor but it makes it very difficult to get an accurate temperature reading because the enclosure heats up and you cannot have a good distance from the active components to the temperature sensor.

Wouldn't just correction factor be enough ? If device takes constant power it should also heat the sensor by constant amount

Re: Air quality monitors: paying more does not get you more accuracy

#112

Post by neogodless »

ilyt wrote: post #104
hammock wrote: post #18

Earlier quoted context omitted.

The same is true of digital bathroom scales. In fact almost all consumer grade digital scales have “fake accuracy” built into the firmware that ensures the same exact weight shows up when you step on the scale twice in a row, even if you pick up e.g a quarter-pound weight in your hand the second time

Source on that ? Never saw that and just checked my cheapo, it doesn't do it

My Bowflex scale does this. I tend to switch modes / user profiles if I care about accuracy.

Re: Air quality monitors: paying more does not get you more accuracy

#113

Post by ahaucnx »

ilyt wrote: post #111
ahaucnx wrote: post #102

Earlier quoted context omitted.

We originally designed a smaller monitor but it makes it very difficult to get an accurate temperature reading because the enclosure heats up and you cannot have a good distance from the active components to the temperature sensor.

Wouldn't just correction factor be enough ? If device takes constant power it should also heat the sensor by constant amount

Yes to some extent but the correction factors will be influenced by absolute temperature levels, airflow in the room etc.

Re: Air quality monitors: paying more does not get you more accuracy

#114

Post by RicoElectrico »

hammock wrote: post #18
ahaucnx wrote: post #3

Author here. I wrote this article a few weeks ago after discovering that a well known air quality monitor in the market that retails for more than USD 1000 actually uses a PM module that costs less than USD 20. Often people assume that the more expensive, the better but as you can see in the article this is often not the case -especially when it comes to the accuracy of the monitor. If you are looking for an open sou…

The same is true of digital bathroom scales. In fact almost all consumer grade digital scales have “fake accuracy” built into the firmware that ensures the same exact weight shows up when you step on the scale twice in a row, even if you pick up e.g a quarter-pound weight in your hand the second time

I can recommend Xiaomi Smart Scale 2 (not the body composition one, it's nonsense). It is very accurate and repeatable. So much so, that you can see your weight drop after you go to the toilet.

It is fascinating how much one's weight fluctuates during the day (or night which is even weirder if you don't eat/drink anything!)

Re: Air quality monitors: paying more does not get you more accuracy

#116

Post by q87b »

aulin wrote: post #36
hammock wrote: post #18

Earlier quoted context omitted.

The same is true of digital bathroom scales. In fact almost all consumer grade digital scales have “fake accuracy” built into the firmware that ensures the same exact weight shows up when you step on the scale twice in a row, even if you pick up e.g a quarter-pound weight in your hand the second time

I wouldn't say it's the same. Low cost air quality measurement is difficult. PM is tricky but almost manageable with laser scattering, toxic gases at typical inquinant concentrations are almost impossible to get right with electrochemical sensors, no matter how much money you throw at them. Weight measurement is easy, they could give you precise and accurate results but most customer base doesn't understand anything…

Easy solution though, just limit the scale's display to a magnitude that it can accurately measure reproducible.

Re: Air quality monitors: paying more does not get you more accuracy

#117

Post by mnw21cam »

ahaucnx wrote: post #3

Author here. I wrote this article a few weeks ago after discovering that a well known air quality monitor in the market that retails for more than USD 1000 actually uses a PM module that costs less than USD 20. Often people assume that the more expensive, the better but as you can see in the article this is often not the case -especially when it comes to the accuracy of the monitor. If you are looking for an open sou…

Please could you consider changing the CSS on the article. At the moment, the web page has "display: block" on almost everything, which does exactly what it says on the tin and produces a blank white page, which does make it a little difficult to read the content.

Re: Air quality monitors: paying more does not get you more accuracy

#118

Post by jve »

plett wrote: post #80
ioulian wrote: post #61

For people who use Home Assistant, I've gone with DIY route with ESPHome [1] and senseair CO2 sensor. You can buy those sensors for +- 26 USD on AliExpress. Together with 5 USD, ESP32 devkit, it's mostly "solder"-n-play. Of course, I only have one of them, so I can't say if they are accurate, but I just need to know if the CO2 levels are normal (+- 400ppm) or high (+1000ppm), to open a window. I have tested it with j…

I attached a cheap IKEA Vindriktning PM2.5 sensor to esphome to get air cleanliness data into Home Assistant [1]. That's also very simple to do - solder some wires and write a few lines of yaml and it shows up in the web UI. I bought two of them and they are accurate to each other, so the sensors appear to be acceptable. [1] https://plett.uk/posts/ikea-air-sensor/

They are extremely inaccurate. But relative measurement is OK - you can see rising or falling pollution. When I put one in kitchen it "died" pretty fast - I think the cooking oil grease got onto the sensor and it is game over for me. Shows MAX PM2.5 all the time.

Re: Air quality monitors: paying more does not get you more accuracy

#119

Post by RobotToaster »

ahaucnx wrote: post #3

Author here. I wrote this article a few weeks ago after discovering that a well known air quality monitor in the market that retails for more than USD 1000 actually uses a PM module that costs less than USD 20. Often people assume that the more expensive, the better but as you can see in the article this is often not the case -especially when it comes to the accuracy of the monitor. If you are looking for an open sou…

You appear to be using CC BY-NC (although it's ambiguous if that applies to the schematics/3d files or only the instructions?) which isn't an open source licence, as it violates point 6 of the open source definition. [0]

Sorry to be pedantic, but it spoils an otherwise interesting looking project.

[0] https://opensource.org/osd/

Re: Air quality monitors: paying more does not get you more accuracy

#120

Post by noja »

plett wrote: post #80
ioulian wrote: post #61

For people who use Home Assistant, I've gone with DIY route with ESPHome [1] and senseair CO2 sensor. You can buy those sensors for +- 26 USD on AliExpress. Together with 5 USD, ESP32 devkit, it's mostly "solder"-n-play. Of course, I only have one of them, so I can't say if they are accurate, but I just need to know if the CO2 levels are normal (+- 400ppm) or high (+1000ppm), to open a window. I have tested it with j…

I attached a cheap IKEA Vindriktning PM2.5 sensor to esphome to get air cleanliness data into Home Assistant [1]. That's also very simple to do - solder some wires and write a few lines of yaml and it shows up in the web UI. I bought two of them and they are accurate to each other, so the sensors appear to be acceptable. [1] https://plett.uk/posts/ikea-air-sensor/

Do you know if the new ikea air quality sensor has the same fan as the first one? The original had a fan that would turn on and off every ten seconds.
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