I have a similar scenario although mine is on the heating side. In my case the proposed building is using purchased heat via a low-temp geothermal water source that can be purchased from the local District. The baseline is required by App G to be VAV w/ reheat using design supply hot water temp = 180 deg F. The geothermal source is 110 deg, so it can't be used in the baseline scheme with standard hot water heating coils. This situation is different than Andy's in that using the geothermal source results in a tremendous cost savings to the owner. The proposed system will use Water-Water Heat Pumps to take about a 65 degree temperature drop out of the 110 deg source. The cost of the source is based on gallons usage, with no regard for heat transfer. The rate schedule is set to be equivalent to the cost of natural gas assuming a 20 deg temperature drop. So in essence, every degree the system can take out past 20 deg is free heating energy, which I'm hoping the modeling protocol allows credit for.

So, I am interested if there is any insight out there on what to do when the baseline and proposed systems utilize separate utilities.

Thanks,

Dan Russell, EIT