What are the principal advantages of using a single building information model of the existing conditions as the foundation for modeling proposed additions or renovations?

By using a single building information model, we are able to interact with the existing built conditions when modeling our proposed additions and renovations. In many cases, we may need to demolish or add things into our existing built environment in our proposed plans, and by using a single model, we are able to easily integrate our new construction with the existing. If we started a completely new model, we may make changes/additions in our new model that may not be compatible with the as-built model. Additionally, it provides an easy way for the client to envision the proposed design in the existing built environment.

What sort of complexities are introduced when you construct a building complex in phases?

Some of the complexities that come into places when we construct a building in different phases involves the timing of our construction. When we model with phases, we are introduction a time element, which adds the need to manage when elements will be constructed and potentially demolished, in order for the phases to be properly integrated with one another. In order to manage this, at the start of our design, it is important for us to create different phases and their associated views. In this way, when we begin modeling (in specified views), we are able to keep our phases separate.