This report describes our first attempt to extrapolate the measured energy savings found in two BECA compliations to the relevant portions of the U.S. building stock. We estimate a savings potential of 0.2-0.5 Quads/year (resource) from retrofitting the existing multifamily stock, and roughly 0.2-0.3 Quads/year (resource) from upgrading thermal features in new, all-electric homes built in the next decade. While these estimates are based on actual measured results rather than a theoretical economic and engineering optimum, they do assume complete saturation of the relevant stock segments. Costs of conserved energy are generally well below the current prices paid for that energy. The total cost to implement these measure s is estimated to be about $30 billion for intensive retrofits of multifamily building and $44 billion to upgrade new, electrically-heated homes.