The U.S. Department of Energy (DOE) conducted a final quantitative analysis to assess whether buildings constructed according to the requirements of ASHRAE Standard 90.1-2010 would result in energy savings compared with buildings constructed to ASHRAE Standard 90.1- 2007. The final analysis considered each of the 109 addenda to ASHRAE Standard 90.1-2007 that were included in ASHRAE Standard 90.1- 2010. All 109 addenda processed by ASHRAE in the creation of ASHRAE Standard 90.1-2010 from ASHRAE Standard 90.1-2007 were reviewed by DOE, and their combined impact on a suite of 16 building prototype models in 15 ASHRAE climate zones was considered. Most addenda were deemed to have little quantifiable impact on building efficiency for the purpose of DOE’s final determination. However, out of the 109 addenda, 34 were preliminarily determined to have a measureable and quantifiable impact.