When first thinking about analogies between living organisms and building systems, my mind comes to the similarities between piping systems within a building and the veins and capillaries in the human body. Not only are they both visually similar with the complex interconnectedness, but they are both networks of tubes delivering essential “nutrients” to end points for both systems. They are both vital parts to the system function and operation.
Another analogy worth thinking about is the exterior envelope of a building and its similarity to that of skin on a person/animal or bark on a tree. It is the first line of defense against rain, temperature changes, abrasions, and anything else on the exterior. Damages in this exterior envelope can harm functionality of the systems within (a cut or scrape may lead to an infection while a broken window can lead to large temperature swings and increased heating/cooling load).