I've got a 92,000 square foot Industrial building that I am modeling.
If you went by Table G3.1.1A, the baseline system type would be System 5
- Packaged VAV with reheat.

However, of the 92,000 square feet, approximately 16,000 sq ft is
conditioned to standard 75/72 degrees, while the remainder is a mixture
of storage, manufacturing, etc, and is heated to 55 and cooled to 120
(no actual cooling in proposed model, but you've got to insert some sort
of cooling system per App G).

So I really have 16,000 sq ft that is fully conditioned, and 76,000 sq
ft that is only partially conditioned (ie the peak thermal load differs
by 10 Btu/h-ft2).

Any guesses how I configure this?

Do I have a packaged VAV system for the 76,000 sq ft of shop/storage and
isolate the 16,000 ft2 of real conditioned space as system 3 per the
Exception to G3.1.1?

Or do I have a packaged VAV system for the 16,000 ft conditioned space
and isolate the 76,000 sq ft as system 3?

To further complicate things, since the 76,000 sq ft is split between
storage and manufacturing, where there is theoretically an operating
schedule that differs by 40 hours or more a week between these two
different use types, do I actually just end up with ALL system 3 even
though the total net building area is above the 75,000 sq ft cutoff
where we're supposed to go to System 5?

I'm confused! Any help would be appreciated.

To recap:

16,000 sq ft office, heated/cooled to 72/75

30,000 sq ft of storage with basically no operating hours per week,
heated/cooled to 50/120

36,000 sq ft of manufacturing / workshop area that is used approximately
50 hrs a week, heated/cooled to 50/120

Mixture of System 3 and System 5, or ALL system 3?

James Hansen, PE, LEED AP