Open Back Better Act of 2020 This bill directs the Department of Energy (DOE) to provide grants to federal and state agencies and tribal organizations to implement building projects that increase resiliency, energy efficiency, renewable energy, and grid integration. It also provides grants for projects that may have combined heat and power and energy storage as project components. States must use at least 40% of grant funds to implement projects in environmental justice communities or low-income communities that have been adversely impacted by the COVID-19 (i.e., coronavirus disease 2019) pandemic. No funds may be used for a project unless all of the iron, steel, and manufactured goods used in the project are produced in the United States, with specified exceptions. The bill also directs DOE to hire a specified number of employees to carry out the grant program, including at least 300 full-time employees in the Office of Energy Efficiency and Renewable Energy.