Energy may interact with condition rather than act independently. Buyers could tolerate weak performance in a fully renovated home, or reject it because they do not want to undo finished interiors.
Plumbing access deserves its own conversation. Ask where pipes can be reached, which walls or floors would need opening, and who pays for reinstatement. In a small multifamily, also establish which runs serve only the renovated space and which may be shared. That responsibility should be...