This standard covers a. new buildings and existing buildings or portions thereof; b. the determination and expression of building energy performance and the estimate of greenhouse gas emissions associated with that energy use; and c. techniques for the comparison of the energy performance and associated greenhouse gas emissions between different buildings@ alternative designs for the same new building@ or for improvements in the operation of existing buildings. This standard does not a. establish building energy performance or greenhouse gas emissions goals or limits; b. present a method for certification of prediction methodology@ such as computer programs; c. address embodied energy of building materials and systems; or d. incorporate transportation energy or associated greenhouse gas emissions for building functions@ including commuting@ business travel@ and process transportation. PURPOSE This standard is intended to foster a commonality in determining and reporting the energy performance of buildings to facilitate a comparison of design strategies or operation improvements in buildings as well as the development of building energy performance standards and reporting of greenhouse gas emissions associated with building operation. It provides a consistent method of determining@ expressing@ and comparing the energy performance of new and existing buildings and greenhouse gas emissions associated with the design of new buildings and operation of existing buildings.