I'm modeling a one story building that consists of 11000 sqft office and 16000 sqft of conditioned warehouse.  Per 90.1, the baseline system should be System 5 since the conditioned area exceeds 25000 sqft.  

Per exception 3.1.1b, since the office and warehouse areas differ signifcantly (more than 10 Btu/h/sqft), the office area (being the lesser of the two areas) should be modeled with System 3.  

However, this means that the 16000 sqft warehouse no longer meets the requirements for System 5.  Should it be modeled with System 5 anyway?  Does it need to be System 3 as well?  If it's system 3, does that mean it no longer qualifies for exception 3.1.1b, and I have to use System 5 for the whole building, and am now stuck in an energy modeling time loop?

Any help is appreciated.