Human thermal responses to temperature ramps in moderate built environments

Abstract

Current studies demonstrate that uniformly stable indoor thermal environments do not completely ensure the thermal comfort of residents, and unreasonable temperature settings can cause discomfort and high energy consumption. Moreover, temperature ramps frequently occur in actual indoor environments. Thus, it is important to understand human thermal responses in moderate environments with temperature ramps to improve working conditions and reduce energy consumption. In this regard, an experiment using within−subjects design in a chamber was conducted to evaluate the effects of temperature ramps on human thermal responses. A total of 60 healthy participants (30 females and 30 males) were recruited to participate in the tests. Their subjective responses, thermal comfort and sensation, thermal acceptability and preference, humidity perception and facial thermal sensation were collected during the experiments. The results showed that temperature ramps significantly affected the thermal sensation, thermal comfort, and facial sensation in the ramp-down environments but not significantly in ramp-up environments. However, the effect of temperature ramp-down on the humidity sensation was only significant for the female participants. A 2 °C temperature ramp-up did not affect the thermal comfort of the participants and was acceptable for them. The male participants were more receptive to ambient temperatures than the female ones, whereas the female participants were more sensitive to cool environments than the male ones. Moreover, good fitting relationships between the thermal sensation and the thermal comfort, as well as the thermal sensation and the facial thermal sensation were observed. This study provides some references for the influence of temperature ramps on human thermal responses in actual indoor environments, and recommends temperature set points to reduce the use of cooling energy.