Can a tool effectively aid user experience (UX) and user interface (UI) designers, along with frontend developers, in implementing more energy efficient websites? The foundation for formulating the thesis questions and identifying the issue was laid through an exploration of related work. This study aims to present the development of a tool encompassing recommendations and practices from existing research, providing valuable support for designers and developers.  Several methods, namely six, were established to better define and concretise the problems. The idea phase continued exploring potential solution both through looking at similar solutions as well as doing workshops together with potential users. In this phase the guidelines, now named SCOPES - System Conscious of Potential Energy Saving, started taking shape. The prototype was designed to assist web designers and developers in reducing energy consumption during website development. The study and especially the test phase found that guidelines empowered web designers to create energy efficient web pages, and users accept lower energy pages when aware of their efficiency, given that essential functionalities are retained.  The results of this thesis, supported by a total of 16 methods and 64 users with various backgrounds, ethnicities, and genders, emphasize the importance of addressing the challenges, posed by our energy-demanding society, pointing to potential pathways for a more sustainable and efficient future.