Accessibility, sociability, rentability, and sustainability were driving factors for their design. The focus of the design was aging-in-place for both dwellings. A secondary goal was energy-efficiency so that the dwellings would be less expensive to heat and cool. They insulated the units with R-40 walls and an R-60 roof. Tight air sealing was also important and they ultimately achieved 2.2 Air Changes per Hour (ACH).