Title III of the Energy Conservation and Production Act, as amended (ECPA), establishes requirements for building energy conservation standards, administered by the DOE Building Energy Codes Program. (42 U.S.C. 6831 et seq.) Section 304(b), as amended, of ECPA provides that whenever the ANSI/ASHRAE/IESNA Standard 90.1-1989 (Standard 90.1-1989 or 1989 edition), or any successor to that code, is revised, the Secretary of Energy (Secretary) must make a determination, not later than 12 months after such revision, whether the revised code would improve energy efficiency in commercial buildings, and must publish notice of such determination in the Federal Register. (42 U.S.C. 6833(b)(2)(A)) Standard 90.1 is developed under ANSI-approved consensus procedures, and is under continuous maintenance by a Standing Standard Project Committee (commonly referenced as SSPC 90.1). ASHRAE has an established program for regular publication of addenda, or revisions, including procedures for timely, documented, consensus action on requested changes to the Standard. 1 Standard 90.1-2016 was published in October 2016, triggering the statutorily-required DOE review process. To meet the statutory requirement, DOE conducted an analysis to quantify the expected energy savings associated with Standard 90.1-2016. This report documents the methodology used to conduct the analysis below. Based on the analysis, DOE has determined that the 2016 edition of the ANSI/ASHRAE/IES Standard 90.1 would improve overall energy efficiency in buildings subject to the code compared to the 2013 edition of Standard 90.1. Methodology The methodology applied in this analysis is consistent with that utilized for previous DOE building energy codes analysis and determinations, and is based on a combination of qualitative and quantitative assessments: