Dears,

I have a project (school), that is meant to be built in 2 phases. Basically they are building half of the school first and will expand it in the future. Phase 1 is meant to be standalone and will be certified separately (potentially even built and completed before phase 2 starts). My problem is the following:

Phase 1 conditioned area: ~ 7,000 m2

Phase 2 conditioned area: ~ 7,000 m2

So the combined area of phase 1 and 2 is above 14,000 m2 which means I need to use ASHRAE system 8 (water cooled chillers) if I am to model the entire school. However, as Phase 1 is being certified independently, my approach is to model phase 1 and use system 6, and then i'll add to the model phase 2. The issue here is that since the total area will classify the building under system 8 baseline, I am not sure how or what system should be used when modeling phase 2. It is good to note that I can not model phase 2 separately as it shares HVAC system with phase 1 (chillers and FAHUs).

 Can anyone provide me some guideline on how to model phase 1 and then phase 2 correctly as per the standard? which baseline systems to use for each phase, and if the phase 1 part of the school should be entirely re-run in conjuction with phase 2 when the time comes?

Thanks for any help.