APPLYING SHANNON AND BOLTZMAN LAWS WHEN SIMULATING THERMAL COMFORT
APPLYING SHANNON AND BOLTZMAN LAWS WHEN SIMULATING THERMAL COMFORT

Summary/Abstract: The body-clothing-environment system is considered to be open and in a state of permanent interaction with the surrounding physical, sensorial, psychological and emotional factors. A human subject who carries out a certain type of activity in a well-defined environment will react differently to the external energetic demands, depending on their nature. A certain activity performed by the human subject represents a source of information – the human subject is the receiver and the environment is the channel through which the information is conveyed. In order to estimate the average quantity of information perceived by the human subject, Shannon defined „the informational entropy” (characterized by low predictability and a high quantity of provided information). The term „entropy” resembles, both formally and through its deduction method, with the „thermodynamic entropy” formula („the entropy of a probability field” or, in other words, „the undefined field”), and the term „informational” sets it apart from the thermodynamic entropy. The link between information and physical entropy was established with the help of the Leon Brillouin equation. On the other hand, in order to estimate the quantity of information, the second principle of the thermodynamics set forth by Boltzman was applied, as a probabilistic law referring to the entropy of a system. Considering the complexity of the thermal transfer between the human body and the environment, only the thermal factors were selected from the wide range of factors which determine the quantity of information that reaches the human subject with a certain body state and within specific environment parameters. The quantity of thermal information resulted from the variation of the environmental parameters was calculated based on the similarity between Boltzman’s thermodynamic entropy and Shannon’s informational entropy. Our paper presents a software application that can be used to determine the optimal comfort temperature and to establish the variation of the pairs of values that characterise air temperature Ta [0C] and the temperature of radiant surfaces Ts [0C] in a definite environment, corresponding to a certain quantity of information linked to the state of “absolute comfort” and of “limit comfort” (a quantity of information of 50 bit/s). In order to achieve our goal, a wide base of data was created so as to include all the variation values belonging to all the factors which influence the quantity of heat Q[Kcal] that is being exchanged between the human body and the environment through all the body’s mechanisms of thermal adjustment (conduction, convection, radiation, and evaporation). The application lessens the quantity of work and the extended time which is necessary in order to solve the calculus algorithm; furthermore, it is designed so as to be an e-learning instrument for both college and masters students, as well as for researchers who carry out their activity in this particular field.

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