: Real world decisions often made in the presence of multiple, conflicting, and incommensurate criteria. Decision making requires multiple perspectives of different individuals as more decisions are made now in groups than ever before. This is particularly true when the decision environment becomes more complex such as sustainability policies study in environmental and energy sectors. Group decision making processes judgments or solutions for decision problems based on the input and 1 Corresponding author Journal of Universal Computer Science, vol. 15, no. 1 (2010), 103-120 submitted: 1/2/09, accepted: 15/10/09, appeared: 1/1/10 © J.UCS