Indoor Air Quality

I strongly suspect my thermostat is lying to me.

Some days I will be shivering, and it says the temperature is 28C.

Some days I will be sweating, and it says the temperature is 18C.

It’s as if it’s measuring the temperature of somewhere else, but the thermostat is in my living room.

So to put the issue to rest, I wanted to get a smart ambient thermometer, to compare measurements. Ideally something with an API which I can use to get the data into Prometheus and graph it.

The Awair Element, on a bookcase.

This is the Awair Element, an indoor air quality monitoring smart device, which measures a bunch of things—including temperature.1 I’ve got one in my living room, and I plan to get one for my bedroom.

It has an API, so I can scrape the data:

$ curl http://10.0.20.117/air-data/latest | json_pp

{
   "abs_humid" : 9.06,
   "co2" : 799,
   "co2_est" : 693,
   "dew_point" : 10.05,
   "humid" : 49.91,
   "pm10_est" : 4,
   "pm25" : 3,
   "score" : 90,
   "temp" : 20.89,
   "timestamp" : "2021-02-06T20:39:13.338Z",
   "voc" : 422,
   "voc_baseline" : 2562694386,
   "voc_ethanol_raw" : 38,
   "voc_h2_raw" : 27
}

And stick it on a dashboard; here’s my Saturday night gaming session:

A dashboard showing various air quality metrics.

It’s February now, so it’s cold. I had all the windows and my living room door shut from a little before 16:00. You can see the CO2 and VOC levels creeping up.

We had a 15-minute break in the middle. I opened the windows and door. You can see the levels drop back down. And then creep up again after the break.

The percentage in the top-left is an overall score based on the other metrics. 80%+ means your air is great, I’ve been aiming to keep it above 90%. The thresholds on the other graphs are based on the thresholds the Awair Element uses: it goes from 1 to 5 dots, which I’ve condensed into three sets of regions (ideal, good, bad).

I find myself glancing at the device (and the dashboard) throughout the day, and opening a window if it looks like I could do with a bit more ventilation.

Even if it’s making the numbers up2 it’s making me get more fresh air, which can only be a good thing.

And yes, my thermostat is lying to me.

  1. Here’s a great video on why you should care about the quality of your air.↩︎

  2. Though I hope it’s not, and the movements on the graphs do correlate with when I have windows open.↩︎