This presentation provides an overview of the scope for RP-1651 and the reference building models that will be used in the analysis performed for RP-1651. The reference buildings cover more than 80% of the commercial building stock including offices, retail, warehouse, healthcare, restaurant, apartments and schools. Reference building models are based on Standard 90.1 and have been used to analyses the energy impacts of new versions of that standard. The models were developed for all 17 climate zones throughout the United States.