Nowadays, air pollution and consequently global warming are the major problems that the earth is faced with. These issues can influence climate change and human health. Building façades can play a significant role in the air quality of the urban environment. Therefore, this study draws upon the ability of nature in controlling carbon dioxide to compare three types of bio-façades (i.e. Water façade, Green façade, and Microalgae façade) and to identify an appropriate one. For this purpose, we analyzed documents and scientific literature qualitatively. Then, we identified the aforementioned types of biological façades and selected the most optimal one through the comparison. Additionally, for this comparison, the analytical hierarchy process (AHP) method was employed that resulted in achieving the higher scores by the microalgae façade among other bio-façades mentioned above. The major criteria considered for the AHP analysis included climatic, economic, architectural, environmental, and structural aspects of using the noted bio-façades in buildings. It should be emphasized that the environmental aspect was obtained as the most influential criterion among others. Finally, some technical tips and design requirements for bioreactors are depicted and discussed along with their upcoming challenges and future research direction.
