The characteristics of a 'green heating system', synonymous with an 'environmentally friendly heating system', are academically defined from the total energy systems' point of view, using the concept of 'reversible mode of heating' in the context of current and future technical, economic and environmental protection. The exergy-based Specific Consumption Analysis approach is used to quantitatively evaluate the influence of subsystems' exergy efficiencies on the overall performance of a heating system. Through a case study in the city of Beijing, it is shown that heating fuel specific consumption and the associated emissions can be dramatically reduced as a result of the implementation of a reversible mode of heating system. A multi-criteria optimization process based on a new evolutionary multi-objective algorithm is undertaken to investigate the trade-off between cost and environmental performances associated with such a system. (C) 2003 Elsevier Ltd. All rights reserved.