baseline and proposed model order in net zero energy buildings

edit

Hi everybody, I modeled an existing building in designbuilder to optimise energy consumption.I want to renovate it as a nearly zero energy building and compare it with ASHRAE model.I was wondering if I should make baseline model from existing model , and then make necessary changes to achieve lower energy consumption than ASHRAE model or apply changes(like PV penels or overhangs) and then make baseline model to compare?Thank you in advance.