This paper presents the application of exergy lost, a thermodynamics concept, as an alternative method to aid the decisionmaking process in the selection of utility design options. Two literature-based case studies comprising the steam generation system and the cooling water system were analyzed. The steam generation system considered two design options to improve an existing system with the deaerator operating at 3.0 barg pressure. The design options were whether to reduce the deaerator pressure to atmospheric level or to maintain the pressure at 3.0 barg but with an addition of an influent preheater to recover excess of low potential energy source. For the cooling water system, the design options were whether to have a cool or hot blowdown. Each design options was simulated on HYSIS process simulation software at steady-state operations. Stream data consisting of mass, energy and thermodynamics properties were extracted from the simulated systems. Exergy balance was then conducted to determine the best design options. The criteria of selection were based on systems which exhibit the lowest quantity of exergy lost. From this study, it was found that the steam generation system with deaerator operating at 3.0 barg with an additional influent preheater was the most efficient. For the cooling water system, the option with cool blowdown turned out to be the more efficient system. These results were in agreement with the published result. Exergy lost has, therefore, been demonstrated as a capable tool to aiding decision-making process in the selection of utility design options.