Evaluation of segmental skin temperature cooling responses in a summer electric vehicle cabin using a thermophysiological model

Electric vehicle (EV) cabins create transient and uneven cooling conditions, but cabin average and whole-body indicators cannot show how cooling is distributed across body regions. This study evaluated segmental skin temperature cooling responses in a summer EV cabin by combining human skin temperature measurements from ten participants, thermal manikin based local boundary conditions, and a thermophysiological model. The model reproduced segmental skin temperatures with root-mean-square error values of 0.12–0.69 °C. A trend-based no-cooling reference was then constructed to estimate the cooling effect of active HVAC operation for each body segment. The analysis distinguished sustained low intensity cooling from stronger accumulated cooling, showing that cooling duration alone can misrepresent segmental cooling performance. The left arm showed the strongest accumulated cooling, with a cumulative cooling effect of 168.34 °C·min and an effective period equivalent cooling intensity of 3.77 °C, whereas the back showed the weakest response (44.69 °C·min; 0.82 °C). The right foot remained above the 0.5 °C threshold throughout the exposure, but its effective period equivalent cooling intensity was only 1.17 °C. These findings provide a compact framework for evaluating non-uniform cabin cooling and identifying body regions where conventional airflow may require complementary localized cooling strategies.