Over time the emphasis on where the most gains can be made in terms of energy efficiency have shifted from discipline to discipline and subsystem to subsystem.

We ask our panel of data centers experts with mechanical, electrical and IT backgrounds how the metrics debate has impacted the way we look at energy efficiency and where more sophistication is required to understand the topic from a more holistic perspective. Have we uncovered all the layers of the "onion" or are there more gains to be made?