Standard 90.1-2007 was chosen for this analysis because it is the baseline energy standard established in the American Recovery and Reinvestment Act of 2009 and the subject of DOE’s forthcoming determination of energy savings for Standard 90.1. An overview of Standard 90.1-2007, as well as a brief comparison to previous versions, is provided as introductory information. States with unique energy codes were not included in the analysis as the codes in these states would be difficult to appropriately compare to Standard 90.1 and most of these states have energy offices that routinely assess their codes against the national codes. In states with codes prior to and including the 2000 IECC or Standard 90.1-1999, those states with no statewide energy code, and home rule states which did not specifically request that another code be used, Standard 90.1-1999 was used as the baseline for comparison. Standard 90.1-1999 was chosen as the default baseline because BECP believes it fairly represents current construction practice in states with older codes or no codes.