Infiltration diff between proposed/baseline models is possible?

I’m modeling a building for C&S in France. Normally in my baseline and proposed models I put the same infiltration (n50 = 0.14 ach) for both buildings. Even if this is an unreal case (since the renovation leads to an improvement in the permeability of the building). I do that because, first 0.14 ach is the minimal infiltration allowed by French regulations, and second because I have never seen in the ASHRAE documentation about improve infiltration in current buildings. Even if the improve of the infiltration rate can make me gain a lot of improvement between baseline and proposed buildings energy requeriements. Anyone of you have already experience in this specific point? Any justification is required from the USGBC if I want to change the infiltration between baseline and proposed buildings? Thanks in advance for any comments/help on this,