Please, correct me if I am wrong!
As I understand it, the energy simulation requirements of EAp2 and EAc1 are NOT identical. If I am correct, for EAp2 you:
Model the proposed design in accordance with Section 11.3 of Standard 90.1-2007 and
Model the baseline building to the building performance rating method in Appendix G.
Then, for EAc1 you:
Model the proposed design in accordance with Performance Rating (PR) Method in Appendix G of Standard 90.1-2007 and
Model the baseline building using the same PR Method as the proposed building.
Calculate the performance improvement of the proposed design compared to the baseline building.
Please tell me if this is not correct. I am not an engineer but this is my understanding of the requirements in LEED-NC 2009.