As data centers become more popular today and power cost and energy consumption exponentially raised, considering energy efficiency in data centers seems imperative. To achieve more energy efficiency and greener data center, we need to define tools to measure these parameters. These tools are known as metrics, which can assess data center energy efficiency, emission level, and accordingly, its greenness. Although there are efforts have been done on data center, a comprehensive and applicable framework to accurately measure data centers’ efficiency and greenness is still scarce. In this study, we explore through diverse metrics and provide a framework of best matched metrics for better and more accurate measurement of data centers’ energy efficiency and greenness.