Re-visitation of the thermal environment evaluation index standard effective temperature (SET*) based on the two-node model

Abstract

The standard effective temperature (SET*) is a common and extensively used model that has long been applied in the ASHRAE standard to evaluate the thermal environment. However, analysis and practical application find that SET* is only accurate for simulations of humans at rest and is relatively inaccurate for simulations during exercise. Using theoretical analysis, we find that certain problems exist in the calculation and hypothesis of the existing SET* model: 1) It is inaccurate to assume that a human subject in the standard environment has the same heat exchange at the skin surface as in the actual environment, if the metabolic rate is different in the actual environment. 2) It is difficult to find a value for the equivalent air temperature (SET*) of the standard environment in which a subject has the same mean skin temperature and skin wettedness as in the actual environment. A modified calculation method for an improved SET* model is proposed based on the results of theoretical analysis and experiments. As a result the prediction accuracy of SET* is improved, particularly in the high metabolic rate region. The improved SET* model shows better performance for the evaluation, design, and control of the thermal environment.