Module 5 - Points to Ponder

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?

• The main advantage for using a single BIM model of existing conditions as the foundation for proposed design models is to ensure that the proposed design fully incorporates the changes (e.g. selective demolition) made to the existing structure. Using different models, at some point the proposed design model needs to incorporate information about the existing conditions, especially as the design process progresses. By using a single building model with existing conditions in place, you as a designer are able to appropriately account for the existing structure - and how you modify it - in the design from the very beginning.
• Additionally, as design can be iterative and things change quickly, having a single source of truth for a proposed design in a single model is way easier (and less prone to error) to manipulate.

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

• What happens at the interfaces between the buildings as the phases advance?
• How can you plan and prepare for these complexities as your create your initial building model?
• When constructing a building complex in phases, the boundary conditions become tricky. When a new building butts up to an existing building, understanding how those two buildings connect, how will they materials need to connect, and how you would selectively demolish is crucial. The condition at a CMU to curtain wall connection can be quite complex generally, but when that new curtain wall butts into existing CMU, it can be come even more so once demolition is accounted for.
• When designing, you can prepare for some of these complexities by intentionally noting and understanding how structures would get demolished and in what state they will be after they are selectively demolished (like cutting an opening through an existing CMU wall to attach other wall types). Understanding this reality will allow you as a design to make decisions about where to demolish and place new structures that will ultimately be constructible in the end. Even in the early design phases, this will be crucial to make sure the proposed design can be actually realized down the line.