A new simplified model for evaluating non-uniform thermal sensation caused by wearing clothing

Zolfaghari, Seyed Alireza; Maerefat, Mehdi

doi:10.1016/j.buildenv.2009.08.015

Cited by 27 publications

(12 citation statements)

References 29 publications

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“…In Fig. 4, the simulated results for skin temperature are compared with Kakitsuba [34] measurements, simulation data of Salloum et al [14] bioheat model, and simulation results of Zolfaghari and Maerefat [35]. It can be seen that obtained results from the present model are in a good agreement with the mentioned empirical and simulated results.…”

Section: Resultssupporting

confidence: 91%

“…4. Comparison of measured mean nude skin temperature (Kakitsuba [34]) and simulated skin temperature (Salloum et al [14], Zolfaghari and Maerefat [35] and the present study) during temperature step change. model results and the empirical data for eight comparative cases.…”

Section: Resultsmentioning

confidence: 95%

“…(35) and (36) such as Q m , w skin , a and _ m bl are influenced by thermoregulatory mechanisms. The metabolic heat production is related to the physical activity of the human body and it can be increased by shivering against cold.…”

Section: Description Of the New Modelmentioning

confidence: 99%

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A new simplified thermoregulatory bioheat model for evaluating thermal response of the human body to transient environments

Zolfaghari

Maerefat

2010

Building and Environment

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a b s t r a c tThermal response of the human cutaneous thermoreceptors depends statically upon temperature and dynamically on the temperature change rate at the depth of the thermoreceptors. Therefore, it is very important to estimate the time-dependent thermoreceptors temperature with a good accuracy. On the other hand, the temperature distribution in skin tissue may be significantly affected by thermoregulatory mechanisms such as shivering, regulatory sweating and vasomotion. In the present study, a new simplified thermoregulatory bioheat model is proposed to describe heat transfer in skin tissue. The new model is constructed by combining the well-known Pennes equations with Gagge's two-node model. In this model, the human skin is subdivided into three layers (epidermis, dermis and subcutaneous) and the time-dependent temperature of skin tissue is obtained by solving the bioheat equations taking into account thermoregulatory mechanisms. The model has been verified by extensive comparisons with the published analytical and experimental results where a good agreement was found. Therefore, the present model can estimate the skin temperature under transient environments with a very good accuracy.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 95%

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A new simplified thermoregulatory bioheat model for evaluating thermal response of the human body to transient environments

Zolfaghari

Maerefat

2010

Building and Environment

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“…When conditions are complex and non-uniform, they show non-linear relationships with thermal acceptability and sensation (Zhang and Zhao 2008), which will vary from indoor conditions. Consequently, these studies may not be appropriate for measuring outdoor heat stress in the ambient environment under a multitude of real world stimuli (Brotherhood 2008), and may not account for sensation differences a human feels on bare versus clothed parts of the body (Zolfaghari and Maerefat 2010). Further review of various outdoor thermal comfort models can be found in Vanos et al (2010).…”

Section: Introductionmentioning

confidence: 98%

“…Most well-validated energy budget models, such as those by Fanger (1970) or Gagge (1971) have been developed from indoor laboratory studies (steady-state) that are non-complex (Hoppe 2002;Huizenga et al 2001). Such models use one-dimensional approaches for heat and mass exchange from the human body, with a clothing system that is uniform over the whole body (Zolfaghari and Maerefat 2010). When conditions are complex and non-uniform, they show non-linear relationships with thermal acceptability and sensation (Zhang and Zhao 2008), which will vary from indoor conditions.…”

Section: Introductionmentioning

confidence: 99%

Thermal comfort modelling of body temperature and psychological variations of a human exercising in an outdoor environment

et al. 2010

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Human thermal comfort assessments pertaining to exercise while in outdoor environments can improve urban and recreational planning. The current study applied a simple four-segment skin temperature approach to the COMFA (COMfort FormulA) outdoor energy balance model. Comparative results of measured mean skin temperature ([Formula: see text]) with predicted [Formula: see text] indicate that the model accurately predicted [Formula: see text], showing significantly strong agreement (r = 0.859, P < 0.01) during outdoor exercise (cycling and running). The combined 5-min mean variation of the [Formula: see text] RMSE was 1.5°C, with separate cycling and running giving RMSE of 1.4°C and 1.6°C, respectively, and no significant difference in residuals. Subjects' actual thermal sensation (ATS) votes displayed significant strong rank correlation with budget scores calculated using both measured and predicted [Formula: see text] (r ( s ) = 0.507 and 0.517, respectively, P < 0.01). These results show improved predictive strength of ATS of subjects as compared to the original and updated COMFA models. This psychological improvement, plus [Formula: see text] and T (c) validations, enables better application to a variety of outdoor spaces. This model can be used in future research studying linkages between thermal discomfort, subsequent decreases in physical activity, and negative health trends.

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Improved predictive ability of climate–human–behaviour interactions with modifications to the COMFA outdoor energy budget model

et al. 2012

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The purpose of this paper is to implement current and novel research techniques in human energy budget estimations to give more accurate and efficient application of models by a variety of users. Using the COMFA model, the conditioning level of an individual is incorporated into overall energy budget predictions, giving more realistic estimations of the metabolism experienced at various fitness levels. Through the use of VO(2) reserve estimates, errors are found when an elite athlete is modelled as an unconditioned or a conditioned individual, giving budgets underpredicted significantly by -173 and -123 W m(-2), respectively. Such underprediction can result in critical errors regarding heat stress, particularly in highly motivated individuals; thus this revision is critical for athletic individuals. A further improvement in the COMFA model involves improved adaptation of clothing insulation (I (cl)), as well clothing non-uniformity, with changing air temperature (T (a)) and metabolic activity (M (act)). Equivalent T (a) values (for I (cl) estimation) are calculated in order to lower the I (cl) value with increasing M (act) at equal T (a). Furthermore, threshold T (a) values are calculated to predict the point at which an individual will change from a uniform I (cl) to a segmented I (cl) (full ensemble to shorts and a T-shirt). Lastly, improved relative velocity (v (r)) estimates were found with a refined equation accounting for the degree angle of wind to body movement. Differences between the original and improved v (r) equations increased with higher wind and activity speeds, and as the wind to body angle moved away from 90°. Under moderate microclimate conditions, and wind from behind a person, the convective heat loss and skin temperature estimates were 47 W m(-2) and 1.7°C higher when using the improved v (r) equation. These model revisions improve the applicability and usability of the COMFA energy budget model for subjects performing physical activity in outdoor environments. Application is possible for other similar energy budget models, and within various urban and rural environments.

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A new simplified model for evaluating non-uniform thermal sensation caused by wearing clothing

Cited by 27 publications

References 29 publications

A new simplified thermoregulatory bioheat model for evaluating thermal response of the human body to transient environments

A new simplified thermoregulatory bioheat model for evaluating thermal response of the human body to transient environments

Thermal comfort modelling of body temperature and psychological variations of a human exercising in an outdoor environment

Improved predictive ability of climate–human–behaviour interactions with modifications to the COMFA outdoor energy budget model

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