Dear All,
I have a question regarding lighting power density with the building area method and with the space-by-space method.
Per ASHRAE 90.1-2016 Table G3.1 No.6 (c), "Where lighting neither exists nor is submitted with design documents, lighting shall comply with but not exceed the requirements of Section 9. Lighting power shall be determined in accordance with the Building Area Method." 
Does that mean 1) If I have a multifamily project, and the dwelling unit lighting system is not specified yet, but the common areas (corridors, leasing office, gym center...) lighting systems are designed already the LPD from the dwelling unit should be determined from table 9.5.1 building area method based on multifamily LPD, which is 0.68 W/sf. And the LPDs for the common areas with the designed lighting system should be simulated the same as what has been designed? If that is correct, were the building area method and the space-by-space method applied to the same project? 2) No matter what kind of methods have been used for the proposed model, the baseline is always using the space-by-space method. If that is true, why is table G3.8 (building area method) still offered in the Appendix G section?
Please advise and please clarify whether the answer works for ASHRAE 90.1-2019 as well.