In the U.S., buildings account for more than 70% of electricity usage and 29% of gas consumption. The math is clear: Climate goals that depend on reducing carbon emissions can only be achieved at scale with significant advancements in building energy efficiency. A new type of policy, a building performance standard (or BPS), is the most powerful tool cities have to drive this change. This two-page fact sheet lays out the basics of building performance standards, new mandatory policies that require building owners to meet performance targets by actively improving the energy performance of their building over time. Readers will learn the basics of what a building performance standard is, as well as the high-impact local outcomes that can be gained through a well-designed standard.