The authors present a short summary of various CBM tools and techniques followed by a discussion of energy monitoring and its uses. They investigate energy consumption in CNC milling machines and compare that with predicted results showing a strong degree of correlation. The data is then examined for stability and repeatability once again demonstrating that energy data is both predictable and repeatable. It is then proposed that by linking this via existing and increasingly popular I4.0 technologies it is possible to develop a system to collect compare and interpret energy data as a Condition Based monitoring tool.