Capabilities and limitations of thermal models for use in thermal comfort standards

Thermal models of the human body and its interactions with the surrounding thermal environment are often proposed, and to some extent are used, as the basis for thermal comfort standards. These models range from simple, one-dimensional, steady-state simulations to complex, transient, finite element codes with thousands of nodes. The models are potentially very useful in that they provide a straightforward means to incorporate the numerous physical variables that affect comfort. Some models can be applied to complex situations which would be difficult, if not impossible, to reflect in simple charts or equations. Whether simple or complex, all of these models have limitations for use in standards. These limitations include the accuracy of the physical simulation and the accuracy of the inputs to the model. Perhaps, the biggest limitation is the accuracy with which comfort perceptions can be related to the physiological variables simulated in the thermal models.