Appendix A envelope U-values in retrofit projects

We are doing a project which is being 10% retrofitted. The reviewer wants us to used the envelope values before retrofitting as baseline and the new envelope properties as the proposed project. So I was wondering, since the changes mostly involve exterior walls and the new type of walls do not vary too much from the previous existing walls do I have to use Ashare 90.1 Appendix A values? The reason I ask is because since the components of the wall are not too different with Appendix A I wont be able to demonstrate a difference between before and after retrofit components. The reviewer has not mentioned Appendix A anywhere though, but Im just asking from experience with other projects.