Beach Green Dunes I and Beach Green Dunes II are two of the largest multifamily Passive Houses in the country. They are adjacent to each other in the Rockaways in NY (in the flood zone) and were completed two years apart. Although they look almost identical, they are very different under the hood. Each has a different structure, envelope (ICF vs Block), ventilation strategy (Unitized vs Centralized), and heating and cooling system (VRF vs. ground source heat pumps) along with several other differences due to changes in city regulations and varying site conditions. Mark Ginsberg (Architect) and Lois Arena (Energy / Passive House Consultant) will present the details of these two buildings, what we have learned and how the developments are performing in an effort to develop best practices for highly energy efficient, multifamily design and construction.