Non-default values for Lr and Mr

Magnus, Unfortunately you are not allowed to change the leakage rate. While this was permitted at one point, the section of the 2009 Reference Guide that permitted this was removed via addendum, here: https://www.usgbc.org/ShowFile.aspx?DocumentID=8603.

Leakage rate skewed the calculations, significantly. Changing equipment life and Mr have small effects. The USGBC Credit Ruling consultants did not catch this when they allowed the Lr to vary via a very old CIR. The original USGBC TSAC (Technical Science Advisory Committee) report clearly stated leakage variations were an issue. Of interest might be the original recommended originally defaults published by the USGBC's TSAC way back in 2004. Just before the conclusions section of the report: "LEED should provide default values for Lr, Mr, and Life, perhaps at 1%, 3%, and 30 yr. A project or manufacturer must provide convincing evidence to support values other than the defaults. Manufacturers’ assertions of low leakage rates based on testing of joints under laboratory conditions would not be considered convincing, because most of the leakage occurs during servicing, rather than as some gradual diffusion process in every installation." Oddly, the recommended values were adjusted to higher values by someone other than the TSAC, making it much harder to earn the credit, especially for small HVAC equipment. Lr is 2% vs. recommended at 1%. MR is 10% vs. recommended at 3%. These two are constant, regardless of equipment type. Life was changed based on life values for equipment type from ASHRAE. This change makes a bit more sense.