I am wondering what the correct assumption should be an infiltration rate in both baseline and proposed models. To date, I have always used 0.25ACH to all zones (including interior zones) which I had thought was the procedure for LEED/ASHRAE 90.1 for both models and was written down somewhere, however now I can't seem to find the reference anywhere in any of the documents. Or maybe there never was one. Is there are official ACH rate to use? or is it up to the modeller? Any help on this matter is much appreciated.