With the obvious substitution of the natural environment with the artificial environment and the inevitable solar heat gain in the Mediterranean climate, energy-efficient facades must be considered in buildings. This paper explores Cellular Automata (CA) as a strategy for retrofitting existing façades with green integrated shading systems optimized for south-oriented office space in the Mediterranean Climate of Alexandria. It is considered a contribution to optimizing daylighting performance and creating a more pleasant indoor environment. The main novelty of this paper is the attempt to use the generative design approach to implement a membrane over existing facades with integrated vertical greens. The paper analyzes the daylight simulations of the studied space using Diva-for-Rhino to pinpoint the best locations for green surface utilization. Then various Cellular Automata patterns are evaluated to select the possible rules for applying the green integrated shading systems. The designed façade performance is then analyzed through the suggested criteria. To explain the positive impact of the retrofitting, a comparative analysis of the findings is concluded together. To conclude this approach can be employed as a tool by interior designers to enhance indoor quality and the visual impact of the interior space.