In this paper, we propose a decision support system for green computing in data centers on campuses. Green computing aims at the development of technologies for a greener and more sustainable planet. In this work we focus on the greening of data centers that house servers on campuses. It is known that servers consume a huge amount of power and incur other costs in cooling and related operations. It is challenging to meet the demands of efficiency and accuracy in data centers while yet promoting a greener environment along with cost cutting. Our work proposes a decision support system based on decision trees and case-based reasoning that mines existing data in order to assist decision-making for better management in data centers. We consider various aspects of the data from an environmental management perspective such as carbon footprint, thermal profiles and virtualization. Issues such as efficiency and accuracy are taken into account here, In this proposal paper, we outline the need for our work, the challenges involved, the proposed approach for building the system, preliminary evaluation and future plans. This work would be of interest to the data and knowledge management community as well as environmental scientists and researchers in related areas.