Human thermal responses to non-uniform cooling from intermittently operated split air conditioners

The intermittent operation of split air conditioners is an important strategy for building energy savings, but the effects of the resulting uneven indoor cooling on the human body have not been fully studied. To explore this issue, this study compared responses in two distinct airflow regions of a room with a split air conditioner: one directly exposed to the cold air supply jet (the jet region) and the other away from the air supply jet (the non-jet region). Three levels of intermittent cooling (from 30 °C to 28/26/20 °C) were tested to examine the physiological and subjective responses of 12 participants. The results showed that: (1) during air conditioner start-stop cycles, there was dynamic uneven cold exposure between the two regions, with differences increasing as the intensity and duration of cold stimulation increased; (2) the two regions showed significant differences in average skin temperature, blood pressure, and subjective responses (except for heart rate); (3) This study proposes a conceptual indicator: temporal accumulation of non-uniform cold exposure (TANCE), providing a quantitative tool for the design and control strategies of split air conditioners.