Thermal comfort of people from two types of air-conditioned buildings - Evidences from chamber experiments

Abstract

Air conditioning has been basically generalized in buildings as the most effective means of cooling in South China; there are two common types of air conditioning: centralized air conditioning system and split-type air-conditioner. The present study recruited 60 healthy young people, half from buildings with centralized air conditioning system (CAC buildings) and half from buildings with split-type air-conditioner (SAC buildings), and exposed them to a wide range of temperatures (20–32 °C) and humidity (50% and 70%) in a climate chamber. The results showed that the mean skin temperature was significantly higher for subjects from the CAC buildings under the non-neutral conditions, whereas there were no significant differences for other physiological responses. The two groups of subjects reported the same neutral temperatures (26.8 °C and 26.6 °C) and thermal sensitivities (0.31 °C-1). The 90% thermally acceptable SET ranges were 24.8–27.4 °C and 24.4–30.1 °C for the two groups of subjects, and the range was narrower by 3.1 °C and the upper limit was lower by 2.7 °C for subjects from the CAC buildings. Thermal history containing intermittent and short-term high & low-temperature exposures in the SAC buildings is suggested to strengthen the occupants' thermoregulatory ability. The long-term experience with a more stable cool environment and the less perceived controls are expected to shape a higher thermal expectation of occupants in the CAC buildings. This study specifies the thermal requirements of people in the two types of air-conditioned buildings, and promotes the understanding of the impacts of thermal history and expectation on human thermal comfort.