Carbon dioxide (CO2) emission reduction targeting is an important move in atmospheric CO2 concentration control. Idea of applying HEN retrofit and fuel switching in existing plant has been proposed to be applied simultaneously in achieving CO2 emissions reduction. Graphical approach combining the mentioned idea has been proposed, but involves potentially time consuming manual procedures. Besides, quality of solution produced greatly depends on designer's experience and judgment, and graphical approach hardly account for the cost factor during the design phase, thus potentially generate complex design. This paper introduces a MINLP model for simultaneous CO2 emissions reduction targeting via fuel switching and HEN retrofit for existing plant. A model execution strategy was proposed along with proposed model. Application of proposed model onto case study proven workability of the model to generates solution for targeted CO2 emissions reduction in minimum payback period manner. © 2011 IEEE.