All existing thermal comfort standards are applicable to naturally ventilated buildings and air-conditioned buildings, except mixed-mode buildings. Split air-conditioned buildings, as a type of mixed-mode buildings, account for a large proportion of current buildings. It is urgent to explore the applicability of thermal comfort standards and determine the energy saving potential in split air-conditioned buildings. In this research, the authors conducted a field study in Changsha, China. Eleven split air-conditioned office buildings were investigated from July to September 2016. 442 valid data sets were obtained. The results indicated that occupants preferred a "cooler" temperature of 26 degrees C, 0.6 degrees Clower than neutral temperature of 26.7 degrees C. Occupants have adapted to thermal environment and accepted higher temperature than that predicted by PPD. 95% of occupants were satisfied with the thermal environment. Compared to PMV model, the adaptive model was more applicable to split air-conditioned buildings. 8.6% of cooling energy could be conserved during summer in split air-conditioned buildings. (C) 2019 Elsevier Ltd. All rights reserved.