Ecotope, Inc., in partnership with Center for Energy and Environment (CEE) and Slipstream, led the Low-Rise Multifamily Study for the U.S. Department of Energy (DOE). The study was intended to develop and pilot a methodology that can be used by states and regional organizations to quantify savings opportunities from energy codes in newly constructed low-rise multifamily buildings. Mirroring the approach established by the Pacific Northwest National Laboratory(PNNL) for single-family residential buildings, this study surveyed nearly 100 low-rise multifamily buildings in Illinois, Minnesota, Oregon, and Washington -- representing a range of climate types from mild temperature to very cold continental. Both common entry and outdoor entry (‘garden style’) buildings were included in the work, and a parallel research project evaluated envelope air tightness and current still-evolving air tightness testing methods. Finally, a set of structured interviews of building designers and other relevant professionals was carried to out to gain more insight into this market. We look forward to sharing the findings on how state-level building codes are being implemented, in terms of both observed characteristics and estimated energy impacts.