Add CO2 sensor

[koarlchen]

We recently deployed a CO2 sensor and noticed, that there is no sensor for it available within the spaceapi json schema. Therefore I propose to add an CO2/carbondioxide sensor to it :) I assumed, that it can be added to the v15 draft? I just copied the temperature sensor section and adjusted it to fit CO2.

As of now, I found three spaces, that already have CO2 sensor data published. Apparently, all three use different names for them:

• CCC Darmstadt: co2
• FabLab Nürnberg: ext_co2
• Nerdberg: carbondioxide

I just took carbondioxide but co2 should be fine too.

/CC @poschi3

[dbrgn]

Nice!

I wonder if it makes sense to add a generic "gas" sensor group for various measurements, e.g. VOC or NOx. Or a generic "air quality index".

Additionally, we could also indicate whether a CO2 measurement is direct, or approximated (using a cheaper sensor that measures CO2 indirectly).

I'm sure @rnestler has some experience in this field 🙂