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?
This is very helpful when designing additions and renovations because you have the building model right there in front of you, so you can reference measurements or anything else in the original design easily, and you can make sure that everything lines up correctly in the new model with the existing building.
What are the principal advantages of using a single building information model of the existing conditions as the foundation for modeling several proposed design alternatives for a portion of the building? Why not create a separate model for each of the design alternatives?
It's easy to switch back and forth between options, and really easy to change which option is the primary option. All of the changes that are made to the building over the process also exist in the same document, so if you change something that affects the option you are able to see it and change the option to fit the new conditions. If you had to make another model for the alternatives, there would be a lot of switching back and forth and confusion in the design process.