The purpose of this paper is to increase the energy effciency of room air conditioners (RAC) while achieving a comfortable indoor space. We pose the problem as a multi-objective optimization problem in which the design variables are the inlet temperature, air speed, and angle. The multi-objective function constitutes of the temperature uniformity of the room and average wind in the room in a region of interest as representative of thermal comfort, and a function of coecient of performance (COP) as representative of the energy consumption of the RAC. Direct-adjoint-looping (DAL) method is used as the method for optimization, which is a gradient-based method. We also compared and analyzed the effects of various models of RACs on energy savings and comfort.