The video (not mine!) explains the settings of a similar system I am using. For more info, go to http://openenergymonitor.org/emon/
Other sites where I publish live data: http://daturach.github.io/
Attic and external Temperature and Humidity situation plus external Pressure. Hosted ion a Raspberry PI. External sensor based on Arduino Nanao, 433 mhx TX, solar powered. Same data sent as IN3AQK call sign on APRS network
TMP36 Temperature Sensor,
Sparkfun Redboard (Arduino Clone),
Raspberry Pi. The sensors are connected to the Redboard. The Raspberry Pi and Redboard talk to each other over I2C (Pi is the master). The Pi updates ThingSpeak.