Cloud computing has revolutionized the IT industry by allowing the supply of elastic computing tools on demand as pay-as-you-go services such as SaaS, PaaS, and IaaS (Beloglazov, Energy-efficient management of virtual machines in data centers for cloud computing. PhD thesis, 2013; Farahnakian et al., Energy and performance: management of virtual machines: provisioning, placement, and consolidation. 2016). Cloud computing has contributed to the reinventing of the way technology resources such as servers, storage, private networks, application platforms, and software services are procured and provisioned. A cloud consumer only requires an Internet connection to connect to a cloud service provider to use these services without placing undue pressure on the resources of their computer or mobile device. A medium-sized enterprise may outsource the demand for computing resources to the Cloud and escape high front-end costs that could be spent on private computational resources and thereby save costs that may arise from hardware and software maintenance and upgrades. A giant enterprise, meanwhile, can also create its own private cloud data center to satisfy the demand for computing services and enhance the process of resource management and provisioning. However, cloud computing infrastructure requires massive energy, sometimes even exceeding the energy requirements of a mid-size town. This chapter discusses the need for energy efficiency and the methodological approach needed to achieve energy efficiency. © 2022, Springer Nature Switzerland AG.