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

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

#101

Post by ahaucnx »

reassembled wrote: post #91
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…

Have you compared the Sensirion SEN55 against the Plantower sensors? I ask because I’ve recently picked up both and have played around with them each individually but haven’t compared them for accuracy yet. The nice thing about the SEN55 is that it contains all of the sensors in one unit (PM1.0 to PM10.0, temperature, Relative Humidity, NOX and VOC). They do cost a little bit more than the Plantower units, about $30-…

Yes, we are looking at the SEN55. The reason we currently still use the Plantowers is that there is a lot more research out there on the Plantower and how it behaves in different environments.

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

#102

Post by ahaucnx »

casenmgreen wrote: post #93
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…

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.

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

#103

Post by ahaucnx »

supermatt wrote: post #68
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…

What is the difference between the indoor/outdoor kit? It seems the outdoor one contains more sensors but is less expensive? (or is this a nod to the article in some way ;)) My partner has a pottery studio with a kiln, it can get pretty smoggy in there when a firing is taking place (its unoccupied during, but it takes a while to settle afterwards), so I want to get a sensor. Are there any add-on sensors you can think…

The outdoor kit focuses on PM measurements with dual PM modules for enhanced accuracy. The indoor kit has in addition CO2 and an optional TVOC sensor.

I think for a pottery studio to measure PM and VOCs is a good start (and CO2 to see how well the ventilation works).

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

#104

Post by ilyt »

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

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

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

#105

Post by ilyt »

autoexec wrote: post #90
chronogram wrote: post #72

Earlier quoted context omitted.

I can find mechanical scales very easily in the Netherlands, but they're more expensive. On Alibaba I see that digital bathroom scales are about $2.50 and with WiFi/Bluetooth it's $6, mechanical scales are double that at $12 while also taking up more volume (more pallets and containers). With volume scale and unique designs, your own skin on the apps, and market specific packaging the margins are only going to get be…

You have to take into account that a digital scale, especially one with an app, is going to be collecting endless amounts of data about you and selling it to anyone willing to pay. Your digital scale will end up costing you again and again for the rest of your life, every time someone uses that data against you. You'll just never be told when it's happening.

...get one without WiFi ? My takes one CR2032 battery every ~7 years

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

#106

Post by criddell »

sidmitra wrote: post #19
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

Yes, but do you(or someone else) have a recommendation of which scale does not do this? Something that's not consumer grade, but not "enterprise cost"

The Nintendo Wii balance board is the only good scale you can get and it isn't expensive. A balance board, Wii, and small TV is probably around $500.

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

#107

Post by ilyt »

Luc wrote: post #71
sidmitra wrote: post #19

Earlier quoted context omitted.

Yes, but do you(or someone else) have a recommendation of which scale does not do this? Something that's not consumer grade, but not "enterprise cost"

I have looked for this myself, and come to the conclusion that it doesn't exist unless you're willing to buy a second hand, bulky hospital scale. Measuring human weight is harder than it seems (we don't stay still). Most scales use a strain gauge sensor that detects bending of a metal arm through changes in resistance. It's pretty noisy and needs averaging. There's some integrated circuits to relate the resistance to…

My $10 +decade old one CR2032 powered one does that just fine.

Accurate enough for weight control (doesn't drift from day to day), no "stuck weight" problem mentioned either. Just need to wait 2 seconds for self calibration to finish

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

#108

Post by autoexec »

ilyt wrote: post #105
autoexec wrote: post #90

Earlier quoted context omitted.

You have to take into account that a digital scale, especially one with an app, is going to be collecting endless amounts of data about you and selling it to anyone willing to pay. Your digital scale will end up costing you again and again for the rest of your life, every time someone uses that data against you. You'll just never be told when it's happening.

...get one without WiFi ? My takes one CR2032 battery every ~7 years

You're right that they're probably harmless if they're not connected to the internet and can't interact with a cell phone.

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

#109

Post by lo_zamoyski »

varjag wrote: post #75
Al-Khwarizmi wrote: post #56

Earlier quoted context omitted.

That should be outright illegal... Why do they allow equipment that deliberately lies to the user?

Because the user otherwise will spot the discrepancy and pronounce "these scales are rubbish" (which in a way they are).

So why not fix the scale so it isn't rubbish?
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