This Standard provides a consistent, uniform methodology for evaluating and labeling the energy performance of residences (Dwelling Units and Sleeping Units). The methodology compares the energy performance of an actual residence with the energy performance of a reference version of the same geometry, resulting in a relative energy rating called the Energy Rating Index. Where the energy performance of the actual residence and the reference version are equal, the Energy Rating Index is 100 and where the actual residence requires no net purchased energy annually, the Energy Rating Index is 0 (zero). This 2019 edition of the Standard is the second edition and its Scope has expanded to include rating procedures for Dwelling and Sleeping Units in buildings of any height.