An Energy Reporting Requirement (ERR) is a policy that requires the owners and/or managers of large buildings to measure and report their annual energy use. Such measures are already in place in places such as the European Union. This background paper provides a foundation for discussing the possible implementation of an energy reporting requirement for operators of large buildings in Toronto. TAF’s long-standing efforts to secure such a requirement yielded success in 2017 when the Ontario government committed to Energy Reporting and Bechmarking Requirements for large buildings across the province.