Every building, from the smallest school to the tallest skyscraper, uses energy. This energy is most often generated by burning fossil fuels, which releases greenhouse gases into the atmosphere and contributes to climate change. Existing commercial buildings offer a significant opportunity for low-cost, immediate emissions and energy cost reductions via efficiency upgrades. Energy efficiency can also be designed and built into new buildings. The benefits of energy-efficient buildings have not gone unnoticed by the building design, construction, and operations and maintenance professions. Multiple standards for green building, energy efficiency and sustainable construction have taken root worldwide. Leadership in Energy and Environmental Design (LEED), Green Globes and the Collaborative for High Performance Schools (CHPS) are three of the larger and more widely recognized green building certification systems. Although they differ in scope and purpose, they share one important characteristic: the inclusion of EPA energy performance, measurement, and tracking tools.