Hello, Jeff Ross-Bain,

There is a baseline system type exception in Section G3.1.1. It lists three
cases which shall model different with your major baseline system.

As the requirement of this section:
i) The area is larger than 1900 square meters (20,451.43 square feet)
ii) The space has a differ significantly from the rest of building
iii) The space has a special pressurization relationships, or
cross-contamination requirements, or code-required minimum circulations
rates

i) and iii) are unusual cases, in my opinion you should check the second
exception case for your model.