The Department of Energy has concluded their study of the 2010 version of ASHRAE 90.1, Energy Standard for Buildings Except Low Rise Residential Buildings. DOE has determined that this newest version of the standard will produce a national savings of 18.2% and a site energy savings of 18.5% in comparison to the 2007 version of the standard. This will require that individual states review their code requirements and adopt or exceed the 2010 edition by October 18, 2013.
ASHRAE 90.1 is used as the baseline gold standard for energy efficiency in LEED, the International Energy Conservation Code and most energy standards. You can view the complete determination as reported in the Federal Register at the following: http://1.usa.gov/nQUugb.