This is the greatest opportunity when being able to start from a clean sheet of paper. As part of my presentations I always highlight the fact that 30% of the power entering the data center is consumed by IT equipment (servers, storage & networking). This IT equipment indirectly drives the remaining 70% of the energy which is required for cooling, UPS, etc.) while additionally driving the capital expenses for these same items. By the way, don't forget about the expense of the backup generator to keep this data center 24/7.

It is imperative that the right decisions are made in the category of IT equipment selection keeping in mind the tremendous economies afforded with server/storage virtualization. These advantages result in a drastic reduction in the amount of physical hardware and stress to the data center infrastructure.

Once the IT equipment picture is clear the proper sizing of the remaining infrastructure including backup generator, cooling, UPS and physical data center size becomes obvious.