Looking for form, finding structure

I am currently looking at developing a parasitic architectural form that can be attached to an existing building and use the buildings waste to generate and distribute power to it. In this way I do not see it as truly parasitic but beneficial to the building it is attached to in a symbiotic way.

This rooftop office by Wolf D. Prix and Heimut Swiczinsky is a good example of a modern intervention on an existing building. In this case the lawyers office is attached to a nineteenth century city block

In order to investigate the type of parasitic structure that I would like to create I have looked at four different ways nature finds to attach to a tree.