Daylight is one of the primary factors of thermal comfort. In warm regions, this factor is the cause of excessive heat absorption and energy loss due to further need for cooling solutions. Therefore, design of exterior facade as a sun-exposed structural envelope can play an effective role in indoors heat absorption. Natural structures use several solutions for optimal control and management of daylight. Mimicking these solutions can prove effective in achieving energy optimization and thermal comfort conditions. This paper aims to provide such solution by assessing and mimicking the structure of cactus and designing an efficient exterior accordingly for residential buildings located in hot climates. The results show that presence of suitably sized indentations and protrusions in the walls reduce heat absorption and energy consumption.