Validation of an individualised model of human thermoregulation for predicting responses to cold air

Abstract

Most computer models of human thermoregulation are population based. Here, we individualised the Fiala model [Fiala et al. (2001) Int J Biometeorol 45:143-159] with respect to anthropometrics, body fat, and metabolic rate. The predictions of the adapted multisegmental thermoregulatory model were compared with measured skin temperatures of individuals. Data from two experiments, in which reclining subjects were suddenly exposed to mild to moderate cold environmental conditions, were used to study the effect on dynamic skin temperature responses. Body fat was measured by the three-compartment method combining underwater weighing and deuterium dilution. Metabolic rate was determined by indirect calorimetry. In experiment 1, the bias (mean difference) between predicted and measured mean skin temperature decreased from 1.8 degrees C to -0.15 degrees C during cold exposure. The standard deviation of the mean difference remained of the same magnitude (from 0.7 degrees C to 0.9 degrees C). In experiment 2 the bias of the skin temperature changed from 2.0+/-1.09 degrees C using the standard model to 1.3+/-0.93 degrees C using individual characteristics in the model. The inclusion of individual characteristics thus improved the predictions for an individual and led to a significantly smaller systematic error. However, a large part of the discrepancies in individual response to cold remained unexplained. Possible further improvements to the model accomplished by inclusion of more subject characteristics (i.e. body fat distribution, body shape) and model refinements on the level of (skin) blood perfusion, and control functions, are discussed.

Perception of temperature and wind by users of public outdoor spaces: relationships with weather parameters and personal characteristics

“…The humidex formula (Hx) used as a predictor of the preference to decrease temperature (Fig. 8) lacks a theoretical basis, as opposed to the more sophisticated models (Fanger 1972;Gagge et al 1986;Höppe 1993Höppe , 1997Parsons 1993;Givoni 1998;Havenith 2001;Van Marken et al 2007), but it has a long empirical confirmation, namely in Canada (ACSE 2004) and was related to mortality associated with heat waves in Italy (Bisanti et al 2004;Conti et al 2005). The present work showed that the statistical relation between Humidex and the thermal preference votes was clearly stronger than that of the indices based on energy balance of the human body, such as PET or SET*.…”

Indirect Calorimetry: History, Technology, and Application

“…Room temperature has been demonstrated to affect energy expenditure in healthy adults (45–47). For accurate resting energy expenditure measurement, attention must be given to ensure steady-state conditions.…”

A review of human thermal comfort in the built environment

“…The models of Stolwijk and Hardy [44] and Stolwijk [46] laid the foundation for several more current physiological models such as Fiala et al [48,392], UC Berkeley [49], Tanabe et al [50], ThermoSEM [51,393] and JOS-2 [394], which use between 15 and 19 segments and hundreds of nodes.…”