This document addresses the International Living Future Institute’s (ILFI) Zero Energy (ZE) certification and the PHIUS+ certifications of PHIUS. ILFI and PHIUS consider these certification programs to be highly complementary. The energy efficiency requirements of PHIUS+ provide a targeted pathway focused on high energy efficiency for pursuing Zero Energy. The 12-month performance requirements of Zero Energy certification, in turn, provide a mechanism to validate the outcome of anticipated energy savings from PHIUS+.