I'm currently working in a project of shopping mall (common areas + tenant areas) pursuing LEED certification (Core&Shell). For simulation purposes, the type of HVAC system for the baseline building can be determined for one of the following (with different results):

1) considering the area of all building (tenants + common areas). Result: system type 8 for tenants and system 4 for common areas (differ by more than 31,2 W/m2 in peak loads);

2) considering the area of each tenant unit separately and the common areas: Result: 1 system per tenant (type 8 or 4, depending on the area) and 1 system for common areas (type 4).

These different approaches can lead to very different results in the global performance. Note that each tenant will install its own HVAC equipment.

Can you help me identifying the correct approach?

Thanks in advance,