How the coldest local thermal sensation affects overall thermal sensation after turning on the air conditioning—Evidence from chamber experiments

Abstract

To explore how the coldest local thermal sensation (LTS) affects the overall thermal sensation (OTS) after initiating air conditioner, three experimental scenarios (29 → 23 °C, 29 → 25 °C and 29 → 27 °C) were created to simulate the real circumstances in buildings with split air conditioner (SAC). 29 young students were recruited. The skin temperature of 10 body segments along with the LTS of 6 body segments and OTS were measured continuously. Results showed that the foot demonstrated the coldest sensation and the largest skin temperature change, and it exerted stronger influence on the OTS than other body segments. However, the dominance of the LTS of the foot over the OTS showed great dependence on air conditioner set point temperature and air conditioning duration. Moreover, the two aspects of air-conditioner use behavior interacted with each other when affecting the approaching degree of the OTS toward the LTS of the foot. Based on developing and validating models, differences in the approaching degree change trend over air conditioning duration under different set point temperatures were observed, and then the turning point for the set point temperature between the two change trends was identified. When tset<26°C, the OTS quickly approached the LTS of the foot and surpassed it over time. When tset≥26°C, the approaching speed significantly reduced. The time-varying and temperature-varying characteristics of the relationship between the OTS and the LTS of the foot provided new insight for understanding air-conditioner use behavior in SAC buildings.