The growing desire to use double-skin facades in buildings has increased the importance of relevant research, especially in energy consumption fields. In recent decades, different double-skin facades with various elements between the layers, including shaders, louvers, and plants, have been invented and used. The use of plants in these facades has been of interest because of the higher shading and lower temperature increase. On the other hand, using plants in buildings and their potential to increase thermal comfort is placed as an aesthetic element. This research aims to evaluate the effect of using plants in a southern double-skin facade of an office building in Shiraz on energy consumption. The selected plant is an aquatic fern called Azolla, used as an air purifier in buildings. The double-skin facade of an office building in Shiraz was selected as a sample. Determining the facade components' fixed parameters and variable values, the sample was modeled in the Rhino software and the Grasshopper plugin, and optimization was performed for 288 models (144 with plants and 144 without plants). The depth of the double-skin facade, the external and internal openings, and the glass type were considered as the independent variables, while the cooling and heating energy consumption were considered as the optimization objectives. The results of the research determined 30 alternatives with the lowest energy usage intensity showing that the optimal combination of parameters in two modes (without plants and with plants) are the same. The optimal combination of the parameters includes the depth of the two-skin facade of 0.5 meters, the external opening of 1.9 meters, the external opening of 4.9 meters, and double-glazed laminated glass. The comparison of the optimal results in these two modes shows a 2.35% reduction in the energy usage intensity and 1.70% in the cooling load, with a slight increase in the heating load.