According to DOE's Commercial Buildings Energy Consumption Survey (CBECS), the average energy use for all existing U.S. buildings has essentially remained flat since the early 1980s at about 88,000 Btu/ft2 (277.4 kW/m2) despite public and private initiatives that resulted in increased standards and improved components. Furthermore, 98% of all buildings are less than 100,000 ft2 (9,290 m2) with the distribution heavily weighted to buildings between 25,000 and 50,000 ft2 (2,323 and 4,645 m2). The Greater Philadelphia Innovation Cluster (GPIC) for Energy Efficient Buildings, a Department of Energy Hub, has examined existing buildings, regulations, policies, and current retrofit practices in the ten counties including and surrounding Philadelphia. This paper will provide details of barriers to energy efficiency retrofits of small and medium sizedbuildings and suggest market and technology pathways forward.