An ROI analysis' value is, like beauty, in the eye of the beholder. There are two kinds of cost savings, soft money (qualitative) and hard money (quantitative). Hard money is measurable in generally accepted accounting terms. For example, if a consolidation project lets you retire 15 servers, quantitative savings can be gained from canceling service contracts, reducing facilities costs (power, cooling) and transferring or selling server OS licenses--that's real cash saved, on a daily, monthly or yearly basis. Hard-money savings are the easiest to sell and should be the backbone of your ROI analysis whenever possible.
Speaking of cost analyses, remember that some savings, such as less need for technical support and reduced security risk, are highly subjective. We strongly recommend that you determine early in the game what is important to your company in terms of soft dollars. For instance, some organizations may not place much value on administrative time-savings. Make sure that your projected ROI numbers reflect your reality. Do not let consultants determine the relative value of qualitative factors. Outside contractors can help educate upper management, but at the end of the day, if a given metric has limited credibility in your organization, don't make it the cornerstone of your presentation.
Adjustment 2: Enough for everyone
In the 'burbs, it didn't matter that dad hogged the bathroom for two hours every night after dinner. There were two more bathrooms in the house.
Likewise, in the server room, standardized buying practices and other factors have led to uneven utilization rates. A data center before practical consolidation will no doubt have a number of servers running well under their capacity and some that consistently red-line or come close. A server consolidation project will help you identify specific servers that can be consolidated into one unit to better utilize capacity across the enterprise. This process can be as simple as moving several multiple-purpose servers into one large unit. Another piece of low-hanging fruit is the ability to consolidate systems with similar end-user functions into one company-standard platform.