Showing papers on "Clothing insulation published in 2012"

The UTCI-Clothing Model

Abstract: The Universal Thermal Climate Index (UTCI) was conceived as a thermal index covering the whole climate range from heat to cold. This would be impossible without considering clothing as the interface between the person (here, the physiological model of thermoregulation) and the environment. It was decided to develop a clothing model for this application in which the following three factors were considered: (1) typical dressing behaviour in different temperatures, as observed in the field, resulting in a model of the distribution of clothing over the different body segments in relation to the ambient temperature, (2) the changes in clothing insulation and vapour resistance caused by wind and body movement, and (3) the change in wind speed in relation to the height above ground. The outcome was a clothing model that defines in detail the effective clothing insulation and vapour resistance for each of the thermo-physiological model’s body segments over a wide range of climatic conditions. This paper details this model’s conception and documents its definitions.

Predicting urban outdoor thermal comfort by the Universal Thermal Climate Index UTCI-a case study in Southern Brazil

Abstract: Recognising that modifications to the physical attributes of urban space are able to promote improved thermal outdoor conditions and thus positively influence the use of open spaces, a survey to define optimal thermal comfort ranges for passers-by in pedestrian streets was conducted in Curitiba, Brazil. We applied general additive models to study the impact of temperature, humidity, and wind, as well as long-wave and short-wave radiant heat fluxes as summarised by the recently developed Universal Thermal Climate Index (UTCI) on the choice of clothing insulation by fitting LOESS smoothers to observations from 944 males and 710 females aged from 13 to 91 years. We further analysed votes of thermal sensation compared to predictions of UTCI. The results showed that females chose less insulating clothing in warm conditions compared to males and that observed values of clothing insulation depended on temperature, but also on season and potentially on solar radiation. The overall pattern of clothing choice was well reflected by UTCI, which also provided for good predictions of thermal sensation votes depending on the meteorological conditions. Analysing subgroups indicated that the goodness-of-fit of the UTCI was independent of gender and age, and with only limited influence of season and body composition as assessed by body mass index. This suggests that UTCI can serve as a suitable planning tool for urban thermal comfort in sub-tropical regions.

Parallel and serial methods of calculating thermal insulation in European manikin standards

Abstract: Standard No. EN 15831:2004 provides 2 methods of calculating insulation: parallel and serial. The parallel method is similar to the global one defined in Standard No. ISO 9920:2007. Standards No. EN 342:2004, EN 14058:2004 and EN 13537:2002 refer to the methods defined in Standard No. EN ISO 15831:2004 for testing cold protective clothing or equipment. However, it is necessary to consider several issues, e.g., referring to measuring human subjects, when using the serial method. With one zone, there is no serial-parallel issue as the results are the same, while more zones increase the difference in insulation value between the methods. If insulation is evenly distributed, differences between the serial and parallel method are relatively small and proportional. However, with more insulation layers overlapping in heavy cold protective ensembles, the serial method produces higher insulation values than the parallel one and human studies. Therefore, the parallel method is recommended for standard testing.

The relationship between environmental temperature and clothing insulation across a year

Abstract: People adapt to thermal environments, such as the changing seasons, predominantly by controlling the amount of clothing insulation, usually in the form of the clothing that they wear. The aim of this study was to determine the actual daily clothing insulation on sedentary human subjects across the seasons. Thirteen females and seven males participated in experiments from January to December in a thermal chamber. Adjacent months were grouped in pairs to give six environmental conditions: (1) January/February = 5°C; (2) March/April = 14°C; (3) May/June = 25°C; (4) July/August = 29°C; (5) September/October = 23°C; (6) November/December = 8°C. Humidity(45 ± 5%) and air velocity(0.14 ± 0.01 m/s) were constant across all six experimental conditions. Participants put on their own clothing that allowed them to achieve thermal comfort for each air temperature, and sat for 60 min (1Met). The clothing insulation (clo) required by these participants had a significant relationship with air temperature: insulation was reduced as air temperature increased. The range of clothing insulation for each condition was 1.87–3.14 clo at 5°C(Jan/Feb), 1.62–2.63 clo at 14°C(Mar/Apr), 0.87–1.59 clo at 25°C(May/Jun), 0.4–1.01 clo at 29°C(Jul/Aug), 0.92–1.81 clo at 23°C (Sept/Oct), and 2.12–3.09 clo at 8°C(Nov/Dec) for females, and 1.84–2.90 clo at 5°C, 1.52–1.98 clo at 14°C, 1.04–1.23 clo at 25°C, 0.51–1.30 clo at 29°C, 0.82–1.45 clo at 23°C and 1.96–3.53 clo at 8°C for males. The hypothesis was that thermal insulation of free living clothing worn by sedentary Korean people would vary across seasons. For Korean people, a comfortable air temperature with clothing insulation of 1 clo was approximately 27°C. This is greater than the typical comfort temperature for 1 clo. It was also found that women clearly increased their clothing insulation level of their clothing as winter approached but did not decrease it by the same amount when spring came.

Future Trends in the Development of Thermal Manikins Applied for the Design of Clothing Thermal Insulation

Abstract: Thermal manikins were created with the intention to design and model protective clothing insulation for specific conditions, e.g. military clothing and clothing for divers. At present thermal manikins have a broader use, i.e. to assess the effect of clothing on a human body, to assess its influence on thermal comfort during work in a given clothing ensemble and to test innovative solutions bringing about a reduction in the thermal heat load. When using thermal manikins it should be borne in mind that heat exchange through clothing is, to a large extent, determined by the temperature distribution on human skin. The aim of the study was to find out to what extent thermal manikins can be used to represent the correct distribution of temperature on human skin. To this end, comparative measurements of the temperature distribution on the surface of a standard thermal manikin with a structure generally used and on the surface of the skin of volunteers were performed. The tests conducted showed that for the further development of thermal manikins computer software should be developed which would help to predict the temperature distribution on the manikin surface corresponding to the skin temperature of volunteers. Such software should allow for the simulation of thermal regulatory mechanisms in a human, i.e. an increase in skin temperature caused by vasoconstriction and shivering, as well as a decrease in skin temperature due to vasodilatation and sweating. In a thermally neutral environment, the methods which are currently used to control the thermal manikin seem to be sufficient.

Establishing thermal comfort: characterization of selected performance and physical properties of fabrics used in hospital operating room uniforms

Abstract: The purpose of this research was to characterize selected thermal properties of clothing fabrics available to operating room (OR) workers at the University of Alberta Hospital and to relate the thermal properties to fabric structural characteristics. In this study, we measured the thermal resistance and air permeability of fabrics obtained from surgical gowns, scrubs and warm-up jackets currently in use in ORs in a specific hospital. The results showed that the fabrics from which the surgical gowns were made provide the highest thermal insulation with lowest air permeability, while the warm-up jackets’ fabrics had the greatest air permeability with low thermal insulation values. The clothing options available to workers in the OR fall well below the predicted clothing insulation values for thermal comfort. For workers in the OR, such as anaesthesiologists, who are predominantly sedentary throughout their work shift, the lack of thermally insulating clothing options has consequences for their overall therm...

Theoretical analysis of three methods for calculating thermal insulation of clothing from thermal manikin.

Abstract: There are three methods for calculating thermal insulation of clothing measured with a thermal manikin, i.e. the global method, the serial method, and the parallel method. Under the condition of homogeneous clothing insulation, these three methods yield the same insulation values. If the local heat flux is uniform over the manikin body, the global and serial methods provide the same insulation value. In most cases, the serial method gives a higher insulation value than the global method. There is a possibility that the insulation value from the serial method is lower than the value from the global method. The serial method always gives higher insulation value than the parallel method. The insulation value from the parallel method is higher or lower than the value from the global method, depending on the relationship between the heat loss distribution and the surface temperatures. Under the circumstance of uniform surface temperature distribution over the manikin body, the global and parallel methods give the same insulation value. If the constant surface temperature mode is used in the manikin test, the parallel method can be used to calculate the thermal insulation of clothing. If the constant heat flux mode is used in the manikin test, the serial method can be used to calculate the thermal insulation of clothing. The global method should be used for calculating thermal insulation of clothing for all manikin control modes, especially for thermal comfort regulation mode. The global method should be chosen by clothing manufacturers for labelling their products. The serial and parallel methods provide more information with respect to the different parts of clothing.

Ventilation solutions in clothing

Abstract: There are several solutions to keep the workers at good thermal state at hot or cold workplaces, for example, PCM (phase change materials) and ice; electrically heated clothing; increase/decrease clothing insulation, e.g. with smart textiles; water based cooling/heating; air based systems, ventilated clothes. Following methods can be used to increase the ventilation in the clothes: use of air permeable clothes; increase possibilities for ventilation (design solutions); active ventilation (e.g. fans) etc. Polluted atmosphere may not allow to use the methods above. Ventilation in protective clothing, e.g. for CBRN protection may require inlet air filtering or a separate (compressed) air source. Various solutions have been tested with natural and forced ventilations, and flow rates. Dry and wet tests were carried out. Ventilation is an effective way to increase heat loss. Ventilation utilizes body own capacity (sweating) to regulate heat loss. At extremely high temperatures considerable air flows are required for sufficient cooling: 100 l/min may not be enough. The larger is the ventilated skin area, the more effective it is due to enhanced evaporation. (Less)

Regional thermal sensitivity to cold at rest and during exercise

Abstract: Thermal sensitivity has been of scientific interest for almost a century. Despite this, several research questions within this field remain unanswered, particularly regarding the specific distribution of thermal sensitivity to cold across the human body. Additionally, while exercise is known to cause a cold stimulus to be perceived as less unpleasant according to the principle of thermal alliesthesia, less has been reported on the effects of exercise on thermal sensitivity to cold. With applications mainly related to clothing insulation and design in mind, the present research project aimed to investigate thermal sensitivity to cold at whole body segments, as well as within body segments, at rest and during exercise. Additionally, a comparison of thermal sensitivity to cold between genders and between ethnic groups was also performed.

Predictive clothing insulation model based on outdoor air and indoor operative temperatures

Abstract: Clothing affects people’s perception of the thermal environment. In this research two predictive models of clothing insulation have been developed based on 6,333 selected observations taken from ASHRAE RP-884 and RP-921 databases. The database has been used to statistically analyze the influence of 20 variables on clothing insulation. The results show that the median clothing insulation is 0.59 clo (0.50 clo (n=2,760) in summer and 0.66 clo (n=3,580) in winter). Clothing insulation is correlated with outdoor air temperature (r=0.45), operative temperature (r=0.3), relative humidity (r=0.26), air velocity (r=0.14) and metabolic activity (r=0.12). Two mixed regression models were developed. In the first one clothing insulation is a function of outdoor air temperature measured at 6 o’clock in the morning and in the second one the influence of indoor operative temperature is also taken into account. The models were able to predict only 19 and 22% of the total variance, respectively. These low predicting powers are better than the assumption of constant clothing insulation for the heating (1 clo) and cooling (0.5 clo) seasons.

Adaptive Thermal Comfort for Air-Conditioned Offices in a Warm Sub-Humid Climate

Abstract: One important objective of building design is to provide a comfortable indoor environment. Air conditioning has become a requirement to achieve thermal comfort especially in warm and humid climates. Air conditioning systems are not designed considering aspects related to the interactive behavior of the occupants with their thermal environment, for that reason, occupants feel uncomfortable. In this context the main objective of this research was estimated the neutral temperature (Tn) and the thermal comfort range. Another objective was to identify the factors that affect thermal sensation. A correlation field study with adaptive approach was carried out in Colima City, Mexico. Two data collection methods were used: a questionnaire survey was used to obtain the occupants responses based on the subjective judgment scales and physical measurements were used to obtain weather data. A total of 414 questionnaires were collected during October 2010 to April 2011. The collected data was analyzed by Averages for Thermal Sensation Intervals Method (ATSI). The results showed that the neutral temperature in office buildings with air conditioning was 24.2 °C and the comfort range was 22.6 °C to 25.8 °C. Factors that influence thermal sensation were clothing insulation (clo) and increased use of air conditioning per day.

지능형 빌딩을 위한 ZigBee 위치기반 인간 적응형 HVAC 시스템

Abstract: This paper focuses on human adaptive HVAC system that can regulate the thermal comfort of the resident in intelligent buildings. The thermal comfort is represented in this paper by PMV (Predicted Mean Vote) as defined by ISO 7730. This PMV value indicates how hot or cold a resident feels by considering temperature, humidity, resident’s metabolic rate, relative air velocity, and clothing insulation. In order to develop such a system, a location detection system based on ZigBee module was used along with temperature sensors, other environment sensors. The human adaptive HVAC system was evaluated experimentally on a test bed emulating a room.

Thermal comfort for air-conditioning in Thailand

Abstract: This article presents the principle of thermal comfort, the meaning of predicted mean vote,the comfort conditions and presents the study of thermal comfort in Thailand. Thermal comfortdepends on six quantitative variables: air temperature, air relative humidity, air velocity, meanradiant temperature, human activity and clothing insulation. Thermal comfort also depends onsome qualitative variables: acclimatization to a particular climate, sex, education. Thai peopleacclimatize to hot and humid climate so Thai people can tolerate to higher air temperature thanthe air temperature recommended from ASHRAE. It is hoped that readers can adapt the principleof thermal comfort for energy saving in air-conditioned space.

Data Mining for Prediction of Clothing Insulation

Abstract: Owing to difficulties of gathering large volumes of textile domain data in a context of less mining research, predicting the characteristics of garments becomes an important open problem which receives more and more attention from the textiles research community. In this research work, the field of Data mining attempts to predict clothing insulation factors with the goal of understanding the computational character of learning. Characteristics of clothing learning is being investigated as a technique for making the selection and usage of training data and their outcomes. It is observed from the results obtained by experimentation that the Linear Regression is quiet appealing because of effectiveness in terms of high prediction rate and Linear Regression is able to discover the clothing insulation performance in a most efficient manner in comparison to all other leaning algorithms experimented. Data mining Classifiers has showed spectacular success in reducing classification error from learned classifiers like Linear regression, LeastMedSq and AdditiveRegression functions have been analyzed for improving the predictive power of classifier learning systems.