When assessing energy resources, it is to use a measure called eroi, which is

This is the ratio of energy returned to the amount invested. It is just like any other type of ROI value, in that it seeks to be maximized while investing the least amount of resource possible. Maximizing the ROI allows for a business to use its resources much more sparingly and wisely, in comparison to organizations that have to spend more on resources for a smaller gain.

To wear the full equipment.