Values that we in the Free Software community may take for granted, values such as user autonomy and transparency, as of January 2020 these values are now officially recognized as fundamental for sustainable software design through the Blauer Engel eco-label award criteria. When users decide how software is used, when software development is open for all to see and participate in, communities are empowered. They are empowered to drive down the energy consumption of their programs, with no loss in functionality. Or users may install only what they need, no more and no less, and opt out of advertising and data-mining, thus reducing the number of unnecessary processes running in the background and consuming resources. Additionally, developers may continue to support otherwise unsupported hardware, giving users up-to-date and secure devices, preventing waste landing in landfills. All of the above promote higher energy and resource efficiency, which means lower energy consumed, less CO2 produced, and a longer operating life for devices. Free Software is sustainable software! In this talk I will focus on the energy and resource consumption of software, and I will walk the audience through the 3 steps for obtaining Blauer Engel certification: (1) Measure, (2) Analyze, (3) Certify. I will end the talk with an open call for community engagement, both specifically in applying for Blauer Engel certification and more generally in supporting a resource-efficient, Free Software future.