Thermal integration of a distillation column with the background process through side exchangers (side reboilers/condensers) is important for designing an energy-efficient distillation column. Thermal integration of a distillation column through side exchangers also improves the exergetic efficiency of the column. Invariant rectifying and stripping (IRS) curves are employed for thermodynamic analysis of a distillation column. Different configurations for side-exchanger integration are evaluated based on the exergetic efficiency of the distillation process and they are also compared with feed preheating options. A novel optimal configuration curve is proposed in this paper that identifies feed composition and its thermal condition for which it is beneficial to have a side reboiler in a distillation column.