Website Carbon Calculator - Find out the how much CO2 your website emits
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Wren - Offset your carbon footprint by saving rainforests
ioBroker - flexible and modular application for the IoT and Smarthome
Klima - Go carbon neutral
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation