The 2019 edition includes various modifications and clarifications to improve internal consistency and to standardize the structure and language of the document. Significant changes to requirements include the following Administration and Enforcement New commissioning requirements in accordance with ASHRAE/IES Standard 202 Building Envelope Combined categories of “nonmetal framed” and “metal framed” products for vertical fenestration Upgraded minimum criteria for SHGC and U-factor across all climate zones Revised air leakage section to clarify compliance Refined exceptions related to vestibules, added new option and associated criteria for using air curtains Lighting Modified lighting power allowances for Space-by-Space Method and the Building Area Method New simplified method for lighting for contractors and designers of renovated office buildings and retail buildings up to 25,000 ft2 (2300 m2). Updated lighting control requirements for parking garages to account for the use of LEDs Updated daylight responsive requirements, added definition for “continuous dimming” based on NEMA LSD-64-2014 Clarified side-lighting requirements and associated exceptions Mechanical New requirements to allow the option of using ASHRAE Standard 90.4 instead of ASHRAE Standard 90.1 in computer rooms that have an IT equipment load larger than 10 kW .....