For the CO2 monitoring at #39c3 from the NOC at congress, we crowd sourced the data of https://aranet.com/en/home/products/aranet4-home sensors. This is somewhat a popular portable environmental sensor with also a sensible CO2 sensor. And if enabled, it will broadcast the measurements every second and some info how long ago they where taken etc.
This is not intended as a replacement of the https://datagnome.de/ project by @foosel and @Romses but having just more data points, and specifically moving data points of sensors on people. Plan for next time is to also log all data points the sensors broadcast, and maybe integrate some other vendors if they exits.
To collect the BLE broadcasts of the sensors, we used the aruba-iot integration, all APs we deployed at congress this year had BLE and zigbee radios in there. So we could collect the beacons across all the building. And given we know where the APs are we could map CO2 values to locations. And by filtering already on the APs anything that was not from the manufacturer of Aranet, was not send to our infra.
The code that was handeling this can be found on https://github.com/lub-dub/aranet_aruba_exporter