This book constitutes the refereed post-conference proceedings of the 5th EAI International Conference on Green Energy and Networking, GreeNets 2018, held in Guimarães, Portugal, in November 2018. The 15 full papers were selected form 26 submissions and cover a wide spectrum of ideas to reduce the impact of the climate change, while maintaining social prosperity. In this context, growing global concern leads to the adoption of the new technological paradigms, especially for the operation of future smart cities.