In this episode, we have a very special guest for an episode of Fact Check on Environmental Variables, Ola Fagerström from Microsoft Surface joins host Asim Hussain to talk about his work on the Microsoft Surface Emissions Estimator - an important tool that helps measure the carbon footprint of the device. Ola talks about how difficult it was to take into account everything from materials used, to manufacturing, to packaging, and even end-of-life disposal to give an accurate estimate of the emissions produced by each device; and how these principles can be applied to other areas of green software development.