Exception on LEED_EBOM calculator

From what I know, the CBECS database (which forms the basis of the Case 2 Calculator (Option BC Calculator for v2008), includes exterior energy use. However, since this project needs to follow Case 2, Option 2 (Option C in v2008), you could choose to use the historic data approach. This allows you to compare you current energy performance to a baseline from the same building's historic performance. This will neutralize the effect of the parking size (assuming it hasn't increased or decreased). You can also choose to do the benchmarking that uses historic data + comparable buildings to set the baseline. In this case, you'd either choose comparable buildings that have the same function and a similar ratio of building to parking, or could normalize the data from the comparable buildings accordingly. Good luck.

Jenny, What do you do if you have historic usage, but for 2 buildings combined? We are trying to certify two buildings on the same district heat, but there is only one meter between the two. We know that we need to install a meter so that we can differentiate the two before the performance period starts, but then how do we calculate against our historical baseline?