Cacti – Cactaceae – are distinctive and unusual plants, which have adapted to extremely arid and hot environments. They show a wide range of anatomical and physiological features which conserve water. One such feature, the cacti ribs, help them deal with heat. These ‘cooling’ ribs provideshade on the cactus’ surface against the scorching sun and help improve heat radiation. The alternating planes of light and shade on the vertical cooling ribs produce rising and falling air currents, which recuperate heat radiation. Application ideas have been used in building envelope design and innovation that keeps buildings cool in hot climates.