Fareed, What are the statements your looking for clarification on? If your project is an NC project, you should do one energy model for the facility. You'll have a baseline case and a proposed design case. Look up some past posts on this forum and CIRs about existing building modeling. I want to say 90.1 allows the baseline to be modeled one of two ways: either as the existing building, or as the 90.1 baseline as defined per the standard. Not sure on this - but a little research should clear it up.