There are 6 circuits extending from the electrical room to each unit. Microwave, Refrigerator, GFCI in restrooms, and General use receptacles. In addition there is a common lighting circuit for each two units, and one 2-pole 208, circuit for the PTAC units. We have circuited all rooms according to this protocol. Hence, the number of panels is already set. The base required that we separate the loads for LEED points w.r.t. metering.
Well it all starts at the unit level and adds up all the way back to the main. The hardest part I see is dividing up the lighting and GP/GFI receptacle load. Under the NEC, these load minimums are lumped together and determined by the floor area served.
Start with determining the floor area of each two units served by one lighting circuit (use the outside dim's of walls enclosing the two units floor area). Multiply this by the 3VA/ft? required minimum. Subtract the actual connected lighting load for the two units plus the ampacity of the receptacle circuits times 120V (assumed voltage since you mentioned the 2-pole 208V AC circuit) times the number of receptacles circuits for both units. If there is a positive balance, divide between lighting and receptacle panels at a ratio equal to the number of circuits. If no balance or a negative balance, use actual connected lighting load as the load on the lighting panel, and the balance as the load on the receptacle panel. Don't forget to add in your "house" area circuits too.
From there you sum up your loads per panel and apply the lighting demand factor to each lighting and respective portion of receptacle panels. For upstream equipment, the calculated load prior to applying the demand factor gets carried up, added together, then the demand factor is applied to the appropriate portion of the panel's load.
The remaining loads are all dedicated circuits and get calculated at nameplate value. I don't believe there is any applicable demand factor for these loads.
