One of the dilemmas of this decade seems to be the fact that the need for comfort and high-density cooling increases with global warming while global warming further increases with its resultant CO₂ emissions. This dilemma can only be solved by achieving cooling systems with smaller CO₂ footprints. This effort involves multiple fronts, namely, new, sustainable, and low-exergy cooling systems, highly efficient cooling energy supplies, novel distribution networks, and innovative energy conversion systems. All of these solutions must, however, meet at a common denominator for decisionmaking. In this paper, the common denominator is defined to be the Rational Exergy Management Model (REMM), which provides a robust algorithm to link the supply and demand exergy points in the cooling sector for a given district. The objective is to minimize the CO₂ footprint of the entire cooling sector in a district to guide green cities from split systems to district cooling.