Editor's Note: ANSI/ASHRAE/IES Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, has been a benchmark and national model code for commercial buildings for over 35 years and indispensable for engineers and other professionals involved in the design of buildings and building systems. Now, with well over 100 addenda incorporated since the 2013 edition, Standard 90.1-2016 will significantly change the way buildings are built as these new modifications find their way into the world's energy codes.