CH-12-006 -- An Empirical Thermal Comfort Model for Transient Metabolic Conditions PDF

Human thermal environments constitute various interacting thermal environmental and personal factors which are transient and nonuniform in nature due to the changes within space and time. In this study, human subject tests were conducted to determine the thermal environment perception of subjects in transient metabolic rate (up to 4 met) and dynamic airflow conditions for 23.9°C (75°F) and 28.3°C (83°F) room temperatures. This study focused on the interaction effects of various thermal comfort factors which closely represent actual thermal environments. The subjects' thermal comfort tolerances to warm ambient temperatures (28.3°C / 75°F) and metabolic rates of 4 met in the presence of dynamic airflow were determined. Results showed that dynamic airflow created an awareness of a treatment and people showed higher tolerances for less than ideal thermal conditions. Time constant to resume a steady thermal sensation during and after high metabolic periods is approximately six minutes. Existence of the time constant proved that there is a time lag between the thermal sensation and the level of activity which results in over-estimation of thermal sensation during transient metabolic conditions. A short-term (up to 10 min.) and a long-term (up to 1.5 hours) transient thermal sensation correction models were formulated which are applicable to various periodic high metabolic conditions.