This paper discusses the revisions to ASHRAE Standard 55, which introduces a new Adaptive Comfort Standard (ACS) for naturally ventilated buildings. The ACS allows for warmer indoor temperatures during summer and in warmer climates, based on extensive field studies involving 21,000 sets of data from 160 buildings across four continents. The authors present findings from these studies, highlighting the differences in thermal comfort between naturally ventilated and mechanically ventilated buildings. They argue that the ACS can be used for design, operation, and evaluation of buildings, and for research applications. The paper also explores the energy-saving potential of the ACS on a regional scale across the US using GIS mapping techniques. Finally, the authors discuss new directions for researchers and practitioners in building design and environmental control systems, emphasizing the importance of context, personal control, and the psychological aspects of thermal comfort.This paper discusses the revisions to ASHRAE Standard 55, which introduces a new Adaptive Comfort Standard (ACS) for naturally ventilated buildings. The ACS allows for warmer indoor temperatures during summer and in warmer climates, based on extensive field studies involving 21,000 sets of data from 160 buildings across four continents. The authors present findings from these studies, highlighting the differences in thermal comfort between naturally ventilated and mechanically ventilated buildings. They argue that the ACS can be used for design, operation, and evaluation of buildings, and for research applications. The paper also explores the energy-saving potential of the ACS on a regional scale across the US using GIS mapping techniques. Finally, the authors discuss new directions for researchers and practitioners in building design and environmental control systems, emphasizing the importance of context, personal control, and the psychological aspects of thermal comfort.