Experimental Evaluation of the Indoor Human Thermal Comfort under Different Environments Based on Heart Rate Variability Analysis

Abstract

Indoor thermal comfort of the human body under different environments was studied in this paper using heart rate variability (HRV) analysis. Six male subjects with similar physical characteristics were recruited in the experiment. And electrocardiogram (ECG) data of subjects were recorded continuously in an environmental chamber. Thereafter, the HRV indices were obtained using frequency-domain method, among which we selected the ratio of the low-frequency power and high-frequency power (LF/HF) as an indicator to evaluate the thermal comfort in the study. Meanwhile, questionnaire surveys about thermal comfort and thermal sensation were carried out to obtain the subjective thermal comfort scores of these subjects under various environments. Relationships between mean LF/HF values and mean thermal comfort scores were analyzed based on the experimental and survey data. Results showed the LF/HF was linearly correlated with thermal comfort and thermal sensation scores. Furthermore, higher LF/HF values yielded thermal discomfort, but lower LF/HF values might indicate thermal comfort of the human body.