Research progress on thermal comfort evaluation methods of the bedding system
Sleep is vital to human health,and lack of sleep increases the risk of diseases such as cardiovascular disease and coronary heart disease,as well as impairs emotional regulation and cognitive abilities.As one of the important factors affecting sleep quality,the thermal comfort of a bedding system has been studied by numerous researchers.However,there are no standards to evaluate the thermal comfort of the bedding system,and many studies have chosen different test and evaluation methods.To provide the most applicable method and reference for the research of thermal comfort of the bedding system,the thermal comfort evaluation methods of the bedding system were summarized and analyzed from two angles:the measurement of thermal resistance of the bedding system and the evaluation of thermal comfort of the sleeping human body.First,the measurement methods of thermal resistance of the bedding system and the advantages and disadvantages of each measurement method were presented.The hot plate method is simple and easy to operate,and can measure the thermal resistance of each textile within the bedding system,but cannot directly measure the total thermal resistance of the bedding system.The thermal manikin method can measure the bedding system's total thermal resistance and analyze its thermal comfort in a direct manner,and a small-scale database of total thermal resistance has been established.However,the use of thermal manikins is expensive,the measuring conditions are harsh,and a large number of companies do not have the conditions to use thermal manikins,so there are restrictions in promoting the use of this method.The numerical model prediction method is based on mathematical methods to establish the prediction equations for the total and local thermal resistance of the bedding system;however,the method is restricted to specific bedding systems and has a limited scope of application.Second,methods for evaluating sleep human thermal comfort were summarized and analyzed from the psychological and physiological levels,including subjective thermal evaluation,thermophysiological evaluation,and sleep posture monitoring evaluation developed by subjective questionnaires.Subjective thermal evaluations are mainly conducted by filling out the thermal sensation,thermal comfort,thermal preference,and thermal satisfaction scales proposed by the American Society of Heating,Refrigerating,and Air-Conditioning Engineers(ASHRAE),and published research shows that thermal sensation is usually higher in sleeping humans than in waking humans.The subjective thermal evaluation method is simple and convenient;however,the results are influenced by individual factors such as physical condition,psychological state and age.Thermophysiological evaluation is mostly conducted by measuring skin temperature(average skin temperature)and core temperature.The mean skin temperature is commonly calculated by using the 3-point,7-point,and 10-point methods.The results obtained from various calculation methods may differ,so it is vital to choose an appropriate calculation method based on the purpose of the experiment.Due to the expensive cost of core temperature measurements,few core temperatures are measured in thermal comfort studies of bedding systems.In general,core temperatures are usually maintained between 36.2 and 36.8 ℃ during sleep.Sleep posture monitoring evaluation is based on defining sleep thermal discomfort positions through a subjective questionnaire and then developing thermal comfort algorithms based on visual perception.This method has high accuracy,but it contains limited thermal discomfort sleep positions.The thermal comfort models used for evaluating thermal comfort of the bedding system are mainly divided into two categories:one is a modified model based on the PMV model,and the other is an improved human thermal regulation model based on the Gagge two-node model.These models are generally established based on mathematical equations or experimental data,but they are deficient in personalization,dynamic prediction,and accuracy.Finally,based on the above analysis,the development outlook was proposed.The future thermal comfort measurement method of the bedding system should be developed from three aspects:the determination of thermal resistance of the bedding system,the non-contact sleep thermal comfort evaluation,and the application of machine learning algorithms.
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维普
