Building reuse plus addition

I have the same question, if someone has any information, would be great! thanks. 

Hi Erica - Great question.  My understanding is it depends on whether you're pursuing Option 1/Path 1 or Option 1/Path 2. For Path 1, my instinct here is to compare to how similar calculations were done under v4.  In v4, the BD+C Reference Guide includes sample calculations for Option 3, which is similarly unclear in its descriptive wording around whether the denominator should be the

• full eligible existing building area or
• the total built building area (existing + new).

However, the Futher Explanation-Calculations section of the Reference Guide clears things up.  The sample calculations clearly show that the denominator should be only the existing building area eligible for reuse - i.e., without additions.  Similarly for v4.1 Option 1/Path 1, the intent of this path closely matches that of v4 Option 3 (although removes non-structural elements from calculation).  For this reason, and from the v4.1 credit language "Calculate reuse of the existing project area according to Table 1" - my understanding is that the denominator, as noted above, should be the existing building area.   By contrast, Path 2 requires the denominator to include the total building, both existing and addition, in the denominator.

In the old LEED 2009 version of the building reuse credit, there was a limitation on how big the addition could be relative to the existing building reuse in order to use what is now Option 1 under LEEDv4.1. Has anyone run into anything about using Option 1 vs. Option 2 given the relative size of the existing building to be reused and the new addition being proposed?

We are reusing an existing building however we are applying stud and drywall over the existing structural wall. Do I count the surface area of this wall once for its reuse and again for the laminated surface? Assuming the drywall construction is the same height as the structural wall, the percent of reuse for this wall would be 50%, correct?