Standard 90.1 is ASHRAE’s flagship standard focused on energy efficiency in commercial buildings. The standard is cited in U.S. federal energy legislation and forms the basis for many of the state and local building codes. This presentation will focus on the evolution of Standard 90.1 from its inception in 1975 through the current version. The presenter will then turn attention to development of the 2010 version of the standard targeted at saving 30% more energy than the 2004 version of the standard. Insights into the standards development process will be provided as well the perspective on standards of a previous chair of the 90.1 development committee. The presenter served as the Chair of the committee that wrote the 1999 version of Standard 90.1. (Note: the presentation can address the most recent version of 90.1 which was released in 2013 should the chapter desire this)