@Vladimir_Savchenko sent me a CO2 unit to test. Posting to Emoncms works great 
Config is done via a ChromeApp which then communicates with the device via serial
By default (if ‘host’ is left blank) the Emoncms integration posts to Emoncms.org. See example below setting the ‘Host’ to post to a local emonPi Emoncms
I also tested MQTT wich also worked great. Posting data via MQTT is supported on the emonPi and would be my preferred way to post data to local emonPi Emoncms, as it’s easier to share the data between other services e.g openHAB. Using emon as the base-topic the MQTT messages are automatically converted to Emoncms inputs on the emonPi
