This project proposes a method based on exergy analysis for considering energy efficiency problems. Because exergy is not a concept frequently used by industrials attention has been paid to go through what is exergy and how it can be so useful to enhance the use of available resources. A case study has been taken from a real plant from the chemical industry. A particular attention has been paid to the typical unit operations that are encountered in chemical plants. Unit operations of different types have been submitted to exergy analysis. In particular, the impact of operating conditions around each type of equipment has been highlighted. A systematic approach has been lead to identify new potentials for exergy recovery. Combined with pinch analysis the exergy approach has proved a very powerful tool to enhance exergy recovery between process streams. 58% of the process internal exergy losses have been recovered while Aspen tool for column thermal targeting analysis helps finding new parameters that reduce column internal losses by 60% and its energy requirement by 21%.