I take this post as two separate questions:
1. What metrics are available?
2. What vendor information is available?
1. I feel it would be important to point out that in the dynamic world of both energy and computers it is not easy to calculate usage unless it is after the fact. Without taking into account historical data and applying it to previous usage of hardware to find a correlation it is not an easy matter, especially if a company is changing their equipment.
The Transaction Processing Performance Council has a link to a pdf and more metric calculations at:
This is a great document which provides both equations and examples. This information would be important if a company was trying to gauge its savings should it move into a cloud computing scenario.
The article at: http://www.cioupdate.com/reports/article.php/11050_3849036_3/A-Better-Metric-for-Analyzing-the-Value-of-the-Cloud.htm expounds upon even more points of consideration which could be involved in your metric.
2. To your point, NetSuite offers a basis for its calculations without actually revealing the math:
In any situation you choose, a company is unlikely to share their actual data as it could be used by both competitors and future customers as a leveraging point. Not only that, but if a company publishes a value it could be deemed an advertisement. If that point was found to be incorrect because of things not taken into consideration (e.g. amount of energy used to create the building which houses the equipment, air conditioning costs) then they are now held to the task of meeting those numbers or being put under intense scrutiny.
I wish I had finite answer that could be held to task. I also sincerely hope someone comes along with an argument which destroys both viewpoints here. It would be nice to know that someone was taking energy efficiency seriously enough to develop an applicable tool which was provided to the public.