Yae Hasebe

Usefulness of R-R interval and its variability in evaluation of thermal comfort

The use of R-R interval and the coefficient of variation in R-R intervals (CVR-R) for the evaluation of thermal comfort was investigated. The experiments were carried out with ten male subjects but data from one were excluded from the analysis. Thermal sensation, comfort, and tolerance of environmental conditions were reported and mean skin temperature, R-R interval and CVR-R were monitored during a 3 h period in a climatic chamber with the operative temperature set at 26, 20, or 30° C. Relative humidity was maintained at ca. 50% in each case. At the operative temperature of 20° C, the mean skin temperature was significantly lower, the cold sensation was significantly more intense, and discomfort was significantly greater than at 26° C and R-R interval was increased significantly. Seven of the nine subjects were unable to tolerate this thermal environment. The R-R interval and CVR-R were increased in five and four of those seven subjects, respectively. At the operative temperature of 30° C, the mean skin temperature was significantly higher, and the sensation of warmth was significantly more intense than at 26° C. Seven of the nine subjects felt discomfort, and four of the seven reported an inability to tolerate this thermal environment. The R-R interval and CVR-R were decreased in four and three of these four subjects, respectively. At the operative temperature of 20° C CVR-R was significantly greater than that at 30° C. Together with the subjective indices, R-R interval and CVR-R are considered worthy of further evaluation as objective indications of the effect on people of the thermal environment.

Estimation of thermal sensation using PMV and SET under high air movement conditions

Abstract 1. 1. Our previous experimental results showed the thermal sensation vote was much less than the values of PMV and SET ∗ at air velocities above 0.5 m/s. 2. 2. The method to modify SET ∗ is presented from the results of subjective experiments taking account of decrease in clo value of summer clothing and decrease in skin wettedness due to increased air velocity. 3. 3. Thermal resistance under increased air movement on a standard summer clothing ensemble was measured. Basic thermal insulation of the summer ensemble was reduced by 25% at air velocity of 1.0 m/s. 4. 4. Thirty-two subjects were exposed at operative temperatures of 27 and 30°C under 1 m/s air movement in order to determine the amount of skin diffusion. Measured evaporation heat loss from skin surface was much smaller at air velocity of 1 m/s than that predicted by SET ∗ . 5. 5. Estimated thermal sensation vote using modified SET ∗ agreed well with our previous experimental results under different air velocities for the same clothing.

Effect of two kinds of quilt on the thermal comfort of subjects in a cold environment

Abstract The thermophysiological properties of two kinds of quilt, a ‘kaimaki’ and the popular square kind, which are matched in weight and fiber type of the wad, were determined by laboratory measurements, as well as by climatic chamber tests with human subjects. The thermal insulation rate of the popular square quilt specimen was a little larger than that of the kaimaki quilt in laboratory measurements and the average thermal insulation was almost the same with thermal manikin measurements. However, subjects preferred the kaimaki quilt with regard to thermophysiological comfort in climatic chamber tests under cold conditions. The thermal sensation of the upper arm of the subjects with a kaimaki quilt was also warmer than with the popular quilt, even though the upper-arm was covered by both types of quilt. This was because the kaimaki quilt covered the shoulders and the neck, which are some of the most sensitive parts of the body. Besides this, the closed construction of the kaimaki quilt prevented the penetration of cold air. This was confirmed by a simple hot plate model, which simulated the bed microclimate, which showed that air penetration accelerates convection in the bed microclimate.