DHW Model Inputs

All, We are attempting to accurately model the gas energy usage for the DHW system in a recent residential building. We wanted to confirm that we were accurately doing so, and would not get pushback from the USGBC. We believe that we should be able to make a strong case for substantial savings over the baseline (as opposed to what you would find in an office building), but ASHRAE is not as precise on these inputs as they are on those of the mechanical system. Also, if anyone is aware of a CIR relating to these issues, it would be of great help. Thank you in advance In regards to the baseline, we are modeling the annual usage of gas based on the 80% efficient boilers, LEED baseline flow rates for all fixtures, and daily uses based upon LEED template data. Based upon standard usage, we are assuming 50% of the flow rates from the lavs, kitchen sinks and showers, and therefore would need to be heated. The first level of savings we intend to take advantage of is the higher efficiency of the proposed boilers. This appears to be straight forward and should not see any pushback from USGBC. Thoughts? The second level of savings we would like to take advantage of is the low flow fixtures in the proposed design. We would keep the FTE, usages, etc. equivalent but take advantage of the lower flow rates. This would cut our overall flow, and associated heating requirements, by as much as 50%. These calculations will all be done exterior to the modeling software and input as an annual energy. We believe this to be the accurate way to model the differences, but want to confirm prior to take advantage of a large level of savings. Thank you all.