Efficient buildings should be analogous to biological systems in several different ways. For example, in biological systems the circulatory system is responsible for effectively transporting blood and nutrients around the body; an efficient building should allow occupants to traverse freely without running into bottlenecks or tortuous paths.
Another biological system analogous to buildings is the skeletal system. Much like a skeleton, buildings are made of rigid materials. Despite having a hard skeleton, biological organisms can still move around and take different forms. A well designed building, while structurally sound, should be multipurpose with flexible use cases
One final biological system that buildings can be made analogous to is the nervous system. The nervous system allows for communication and reaction within the body. Similarly, modern buildings should be able to react to their external environment and to internal movement.