Do you actually do anything with the data you collect?

As someone who manages commercial building automation system installations, I have never understood the obsession that HN has with residential IAQ sensors. The number will go up if you cook, burn a candle, use a hairdryer, or if there’s wildfire smoke outside and you have a ducted HVAC installation with an outdoor air intake.

In a commercial BAS, IAQ sensors (CO/NO to be more specific) are used to turn on exhaust and make-up air fans to increase the air quality in a space, but in every single thread about IAQ monitoring on HN, nobody ever seems to use the sensor readings to automate their HVAC equipment to do anything. In fact, almost all commercial BAS systems have zero IAQ sensors (especially in offices), the vast majority of them are use for turning on exhaust fans and make-up air units in buildings where cars are driving inside, like a parking ramp or drive-in warehouse.

I guess my question is, why collect this information and do nothing with it? Maybe you actually do something with it, or you monitor local outdoor air quality as a hobby. I’m asking a more general audience than you specifically.

Lastly, ensuring your house is positively pressurized by paying a testing and balancing contractor to come over and adjust your HVAC system will do more to keep out particulate matter than measuring it ever will.

I use co2 measurements in my home to do just what you're describing here - automate control of a DIY fresh air intake (through a custom built filter box/fan enclosure w/ 5" merv 14 filter).

It's rather dumb at the moment, but when number gets too high, it kicks on for 1 hour and if it's back below threshold it shuts off. There's also a human presence detector that will "pause" it for 5 minutes since it's in my kitchen window.

It's built out of cardboard (laminated, with wheat paste) as a proof of concept/tinker with design and placement of things and also serves as a platform for the cats to nap in the window.

This, mainly, helps from bringing in all the outside humidity during the summer and the bitter cold during the winter. Otherwise, prior, I'd just keep an exhaust fan running all the time (eating the losses on air conditioning/heat) but we'd end up closing the window when it was super hot/cold and then the iaq would get terrible.

Lots and lots of people are automating their various systems due to monitoring these values. An application I've seen lots of is to just kick on the hvac systems fans when the aq drops below a particular threshold in one room or another.

> Lastly, ensuring your house is positively pressurized by paying a testing and balancing contractor to come over and adjust your HVAC system will do more to keep out particulate matter than measuring it ever will.

Sadly, it took me a while to figure out that having this window fan in my kitchen on "exhaust" rather than "intake" was creating a negative pressure environment and that was.. not optimal.

I bought an Awair device in 2020 when my wife and I were working from home full time in the same room, out of curiosity as to whether our office area air was accumulating lots of CO2 during the workday (turns out this is not really an issue in drafty 120 year old houses).

In the time since I’ve found it helpful for: confirming my DIY air purifier was effective during wildfire smoke periods, having a reminder to open the windows generally when the air gets stale and particularly after cooking, learning that cracking a window for makeup air for the range hood makes it much more effective, getting better about trimming candle wicks and snuffing them instead of blowing them out, getting a sense of our actual temp and humidity comfort ranges and how they differ from thermostat settings, and realizing that induction really might be preferable to gas whenever we’re looking to buy a stove in the future.

I used to run https://www.open-seneca.org/. But, personally, it's nice to know the PM value whilst cooking, before going on a run, etc. Permits you to take informed decisions.

I use it to send an alert when CO2 is too high too open some windows

I live in an old 1930s house in the UK so no HVAC or anything more automatable sadly