The smaller the PUE value, the higher the degree of greening of a data center.

Power Usage Effectiveness (PUE) is the standard industry metric for measuring the energy efficiency of a data center. It is calculated by dividing the total power entering the data center by the power used by the IT equipment. A PUE of 1.0 represents a perfectly efficient data center where 100% of the power is used by IT equipment. Any value greater than 1.0 indicates power is being used for overhead like cooling and lighting. Therefore, a lower PUE value signifies less wasted energy and a more efficient, or "greener," data center.

B. This is factually incorrect. A higher PUE value indicates lower efficiency and more energy waste, which is the opposite of being "green."

1. The Green Grid. (2012). PUE: A Comprehensive Examination of the Metric. White Paper #49. Section 2, "PUE and its Derivatives," defines the metric and its interpretation, stating that lower values are better.

2. Huawei Technologies Co., Ltd. (2021). Green Data Center: The Fast Track to a Sustainable Digital World. White Paper. Page 5, "Innovating for xPUE," discusses the importance of lowering PUE as a key goal for achieving green, low-carbon data centers.

3. Gao, P. (2016). A review of data center cooling technologies, trends and metrics. Advances in Mechanical Engineering, 8(10). https://doi.org/10.1177/1687814016668660. This academic paper discusses PUE as the "most popular metric" for energy efficiency, where a lower value is desirable.