I've had this question come up on two separate projects in the last few weeks, from the companies asked to perform the ESA. "Does the ESA Phase 1 only need to cover what's in scope or does it need to include the whole site?" 
Both projects are additions to an existing Hospital, and I can tell they're trying to reduce costs by excluding things off of the ESA that aren't in scope. In LEED 2009 I would have said just do the whole ESA, but v4 and v4.1 requirements seem to require a brand new ESA for every project anyway, so I don't really see any point in doing that now anyway. 

Does anyone know of anything requiring the whole site or just a portion of the site that's in scope? I've scoured the reference guide and LEED credit language and haven't found anything that leans one way or another. I'm inclined to say that reducing the review to what's in scope would be fine, since a Phase 1 will bring up most red flag concerns by the address anyway.