This is true when, and only when, the people paying for energy use are also the people paying for efficiency upgrades. Also, when the people involved are well-informed enough to understand what their options are and just how much energy each will save relative to installation cost. The former rules out nearly all renters and a good fraction of condo and apartment owners. The latter can be far more tricky than many realize, as the impacts (and feasibility) of various changes are highly dependent on the specific building in question.
