We are doing a project in which building is of office type and is having 75 AHUs and each AHU is serving one specific tenant area, means there are 75 tenant. Each tenant area is almost 10,000 SF. Building was built as Core and Shell type, and the scope of developer is limited to AHU only ( AHU is located in AHU Room), all other duct work are under tenant scope ( diffuser, grills and inside duct work)

The problem is that building is old and client built up plan is not available and hence there is not any proof of identification of clear division of zones inside the tenant area like conference , private office, pantry etc.

In this scenario, I have these question
1) How can I identify critical zones if Client Built -up Floor Plan is not available?
2) Can I consider the each client area as a single office zone, which means there will be no critical zones analysis?