This study evaluates the value of technology-agnostic, shiftable flexible building loads in modeled 2030 and 2040 U.S. grids for four types of customers under three potential aggregated distributed energy resources programs. The value examined includes monetary value from providing grid services (e.g., energy, capacity, flexibility reserve, regulation reserve, contingency reserve) and from reducing greenhouse gas emissions. By comparing 845,164,800 simulated shifting opportunities, the study finds that the timing of consumption is critical for profit-driven customers. A program that is activated for 30 critical hours of system operation can result in up to $73/kW per year in revenue for 1 kW of shiftable load. Emission reduction, on the other hand, is best accumulated through a year-round program: shiftable loads can lead to up to 488 kg CO2e/kW carbon reduction per year. The report also provides detailed insights on the trade-off between revenue and emissions, regional variation, short-versus medium-term value, and impacts from various building flexibility parameters, such as shifting window and dissipation. vii This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.