The biggest obstacle for green projects is the resistance to change as it requires people to change their views. Yet, people change their minds all the time, so how do you get people to change their minds in the direction of going green in the data center?

Howard Gardner is recognized expert in analyzing how people think.

This election season, are you wondering if you can
change the mind of a friend who is leaning in the
wrong direction? In Howard Gardner's groundbreaking
book Changing Minds learn insights into the
phenomenon of changing minds and how to bring about
significant changes in persepective and behavior.

The core idea of the book changing minds is in this SAP article.

Changing Minds
By Howard Gardner
Generically, mind change entails the alteration of mental representations. All of us can develop mental representations quite readily from the beginning of life. Many such representations are serviceable, some have notable charm, others are misleading or flatly wrong. Mental representations have a content: we think of these contents as ideas, concepts, skills, stories or full-fledged theories (explanations of the world). These contents can be expressed in words – and in a book, that medium is customarily used. However, nearly all contents can be expressed in a variety of forms, media, symbol systems: these systems can be exhibited publicly as marks on a page and can also be internalized in a "language of the mind" or a particular "intelligence."

Present content and desired content
One should begin by determining what is the present (current) content – be it an idea, a concept, a story, a theory, a skill – and what is the desired content. Once the desired content has been identified, the various competing countercontents must be specified. The more explicitly one can lay these out, the more likely that one can arrive at a strategy suitable for mind changing in the particular instance. Both contents and countercontents may be presented in various formats.
Size of audience
The challenge of mind change is quite different, depending on whether one is dealing with a large audience or a tiny audience. Large audiences are affected chiefly by powerful stories, rendered by individuals who embody their stories in the lives that they lead; intimate audiences can benefit from approaches that are much more individually contextualized. Of special interest are the changes that take place in one's own mind, involving the most intimate kinds of conversation with oneself.
Type of audience
When one is dealing with an audience that is large and heterogeneous, one is dealing with the unschooled mind. Expertise cannot be assumed. Simple stories work the best. On the other hand, when one is dealing with individuals who share knowledge and expertise, one can assume a mind that is schooled and relatively homogeneous with respect to other minds in the group. Stories or theories related to such groups can be more sophisticated, and counterarguments can and should be addressed directly.
Directness of change
Political, business and educational leaders bring about change through the messages that they convey directly to their representative audiences. Creative and innovative individuals bring about change indirectly, through the symbolic products – art works, inventions, scientific theories – that they fashion. In general, mind changes due to indirect creations take longer, but their effects have the potential to last for a far longer period of time. In general, we remember the artistic creators of bygone civilizations far more vividly than we recall the political leaders.
Levers of change and tipping points
Classically, change takes place through compulsion, manipulation, persuasion or through some combination thereof. In this book I have directed attention to deliberate and open attempts at mind change. I have also stressed the classic forms of persuasion: talk, teaching, therapy and the creation and dissemination of new ideas and products. We must recognize, however, that in the future, these low-tech agents may well be supplanted by new forms of intervention: some will be biological, involving transformation of genes or brain tissue; some will be computational, entailing the use of new software and new hardware; and some will represent increasingly intricate amalgams of the biological and the computational realms.
The ethical dimension
As Niccolo Machiavelli pointed out dramatically, skills in bringing about change need not (in fact, he argued, should not) have a moral dimension. Indeed, most of the processes outlined in this book can be carried out for amoral ends, for immoral ends or for impressively moral ends.