Addressing climate change means addressing energy use in buildings. Two-thirds of New York City’s greenhouse gas emissions come from this sector, and the city needed reliable data to create effective policy to reduce emissions and track progress. Enter benchmarking. In 2010, New York became one of the first American cities to collect data about the energy and water used by large buildings. Urban Green was closely involved in creating and promoting the initial benchmarking law 10 years ago, and after a decade, NYC’s benchmarking dataset is the largest and most comprehensive in the country. More important, New York has successfully leveraged this data to implement innovative policies that promote energy efficiency and reduce emissions.