I wonder how I should model a Ventilation system

I wonder how I should model a Ventilation system to comply with Apendix G ASHRAE, it said that my proposed desing shall be consistent with design documens.. This is the description of my system: > There are three Big supply fans in the up roof. This supply fans are designed to supply air to the space for office(there are three vertical ducts where the air will travel from outside to each floor), The ducts for each supply go from the upper roof the the 2nd floor, in each floor there are 3 ducts that will supply air to the space for office. The space for offices are defined in drawing design (just the space, not offices), each supply fan is defined as well (with cfm, Pa, w). However, the space for office is just one per floor, what i want to say is that the scope of work is only to build and core/shell tower office, in each floor, each tenant will define how their office will de inside. > There are from 2 to 3 exhaust fan for each restroom(they are big), in each floor, the air exhausted will travel upper the floor through a vertical duct, where there will be a big exhaust fan that will oust the air outside. The document are for each exhaust fan and for the exhaust fan that is in the upper floor, i mean, equipment and drawing document, that show us there are a vertical duct that take the air exhausted from the restroom and these air will be outs outside using a big Exhaust fan. > > What I think is to model a equivalent supply fan (sum cfm, equal Pa. sum w), same efficiency, this will supply to all the offices spaces. > For exhaut, a equivalent exhaust for each restroom (it will be a little confuse because each exhaust fan in the same restroom are diferent,300cfm, 180 cfm and 265 cfm, also Pa are different, also w), is its? glad you help