These days, IT is increasingly resource-intensive, both in terms of hardware and energy consumption. As a result, the sustainable side of software is an increasingly studied topic in the software engineering community. However, developers have little knowledge of how to write and develop software in a more sustainable way. The aim of this thesis is to find out how to help developers write green code. The more precise subject is to be defined with the developers. The internship is done in the Software Engineering Research Group (SERG) at TU Delft in the Netherlands.