Showing papers on "Clothing insulation published in 2013"

The Universal Thermal Climate Index UTCI Compared to Ergonomics Standards for Assessing the Thermal Environment

Abstract: The growing need for valid assessment procedures of the outdoor thermal environment in the fields of public weather services, public health systems, urban planning, tourism & recreation and climate impact research raised the idea to develop the Universal Thermal Climate Index UTCI based on the most recent scientific progress both in thermo-physiology and in heat exchange theory. Following extensive validation of accessible models of human thermoregulation, the advanced multi-node 'Fiala' model was selected to form the basis of UTCI. This model was coupled with an adaptive clothing model which considers clothing habits by the general urban population and behavioral changes in clothing insulation related to actual environmental temperature. UTCI was developed conceptually as an equivalent temperature. Thus, for any combination of air temperature, wind, radiation, and humidity, UTCI is defined as the air temperature in the reference condition which would elicit the same dynamic response of the physiological model. This review analyses the sensitivity of UTCI to humidity and radiation in the heat and to wind in the cold and compares the results with observational studies and internationally standardized assessment procedures. The capabilities, restrictions and potential future extensions of UTCI are discussed.

Clothing insulation and temperature, layer and mass of clothing under comfortable environmental conditions

Abstract: This study was designed to investigate the relationship between the microclimate temperature and clothing insulation (Icl) under comfortable environmental conditions. In total, 20 subjects (13 women, 7 men) took part in this study. Four environmental temperatures were chosen: 14°C (to represent March/April), 25°C (May/June), 29°C (July/August), and 23°C (September/October). Wind speed (0.14ms-1) and humidity (45%) were held constant. Clothing microclimate temperatures were measured at the chest (Tchest) and on the interscapular region (Tscapular). Clothing temperature of the innermost layer (Tinnermost) was measured on this layer 30 mm above the centre of the left breast. Subjects were free to choose the clothing that offered them thermal comfort under each environmental condition. We found the following results. 1) All clothing factors except the number of lower clothing layers (Llower), showed differences between the different environmental conditions (P<0.05). The ranges of Tchest were 31.6 to 33.5°C and 32.2 to 33.4°C in Tscapular. The range of Tinnermost was 28.6 to 32.0°C. The range of the upper clothing layers (Lupper) and total clothing mass (Mtotal) was 1.1 to 3.2 layers and 473 to 1659 g respectively. The range of Icl was 0.78 to 2.10 clo. 2) Post hoc analyses showed that analysis of Tinnermost produced the same results as for that of Icl. Likewise, the analysis of Lupper produced the same result as the analysis of the number of total layers (Ltotal) within an outfit. 3) Air temperature (ta) had positive relationships with Tchest and Tscapular and with Tinnermost but had inverse correlations with Icl, Mtotal, Lupper and Ltotal. Tchest, Tscapular, and Tinnermost increased as ta rose. 4) Icl had inverse relationships with Tchest and Tinnermost, but positive relationships with Mtotal, Lupper and Ltotal. Icl could be estimated by Mtotal, Lupper, and Tscapular using a multivariate linear regression model. 5) Lupper had positive relationships with Icl and Mtotal, but Llower did not. Subjects hardly changed Llower under environmental comfort conditions between March and October. This indicates that each of the Tchest, Mtotal, and Lupper was a factor in predicting Icl. Tinnermost might also be a more influential factor than the clothing microclimate temperature.

Vehicular Cabins' Thermal Comfort Zones; Fanger and Berkley Modeling

Abstract: This manuscript discusses the development of the thermal comfort zones, during summer and winter periods, inside vehicular cabins This is done using two thermal modeling approaches; specifically Berkeley and Fanger computations The limiting boundaries of the thermal comfort zone when computed by the Berkeley model is determined by the Overall thermal Sensation (OS ± 05), while according to Fanger model, the zone is determined by the Predicted Mean Vote index (PMV ± 05) The Berkeley simulation uses a virtual thermal manikin to predict the thermal sensation and comfort inside the cabin under different environmental conditions, while maintaining the cabin homogeneous state over a relative humidity range of (20-60%) The manikin clothing reflects the summer period through; short sleeve with long trousers at an approximate clothing insulation value of 05 clo Additionally, the winter clothing for winter is long thick sleeve, long thick trousers, hand-wear and footwear with approximate clothing insulation value of 1 clo The metabolic rate for a human passenger is set at 14 met to represent a seated human activity level The same conditions are also used for the Fanger model except the range of relative humidity, which is (20-80%) The results show that the lower and upper temperature limits for the summer comfort window are at standard conditions of 224 and 273°C for the Berkeley model and at 231 and 274 °C for the Fanger model On the other hand, the temperature limits for the winter comfort window are at 198 and 252°C for the Berkeley model and at 186 and 246 °C for the Fanger model Additionally, the proposed study conducted a sensitivity analysis of these windows by changing (increase/decrease) of the metabolism, the cabin air velocity, and the clothing insulation values

Typical Clothing Ensemble Insulation Levels for Sixteen Body Parts

Abstract: Author(s): Lee, Juyoun; Zhang, Hui; Arens, Edward | Abstract: In order to accurately simulate skin and core temperatures and thermal comfort, some human physiology and comfort models now divide the human body into multiple body parts (such as head, hand, chest etc) Most of these parts are normally covered with clothing insulation, which must be quantified in the simulation Unfortunately, existing clothing insulation databases only characterize clothing insulation for the whole body, not for individual body parts That means every body part has the same clothing insulation level, even over the head and hands In this study, we measured clothing insulation for 40 typical clothing ensembles using a 16-segment thermal manikin, and present here the insulation values for each body part, as well as for the whole body

Investigation of Clothing Insulation and Thermal Comfort in Japanese Houses

Abstract: People choose and wear the most comfortable clothing to suit to various thermal situations. In the recent times, we can find the research on the cool biz and warm biz as a potential energy saving measure. However, some researches are conducted only for a short period of time, and some offer only a few samples. In order to clarify the clothing insulation, the thermal measurements and thermal comfort survey were conducted in 30 houses during one year period in Gifu Prefecture of Japan. The subjects numbered 40 males and 38 females. The survey was conducted several times a day. The number of samples collected was more than 21,000. We found the following results. 1. Both in summer and winter, the average clothing insulation of women is greater than that of the men. 2. The clothing insulation is correlated with the indoor or outdoor air temperature. The regression equations can be used to predict the clothing insulation in residential building. 3. The maximum seasonal difference of clothing insulation is 0.36 clo which corresponds to the difference of about 2.1 K in the comfort temperature. The results showed that the clothing insulation is effective for the energy saving.

Report on manikin measurements for ASHRAE 1504-TRP: Extension of the Clothing Insulation Database for Standard 55 and ISO 7730 to provide data for Non-Western Clothing Ensembles, including data on the effect of posture and air movement on that insulation. Results of Cooperative Research between the American Society of Heating Refrigerating and Air Conditioning Engineers, Inc., and the Universities of Loughborough, Lund, Cornell and Hong Kong.

Abstract: ASHRAE standard 55, ISO 7730 and chapter 9 in ASHRAE Handbook-Fundamentals titled ‘thermal comfort’ provide guidance for the assessment of thermal comfort in buildings. As inputs, the method uses climate parameters, the users’ activity level and the clothing insulation of the garments worn by the occupants. The standard provides guidance on the determination of these parameters and provides examples of values for activity level and clothing insulation. However, for the latter, the emphasis is on western style clothing, while in large parts of the world other clothing styles are worn, e.g. shalwar kameez in Pakistan, African clothing in Nigeria or Sarees in India. In order to use the methodology of ASHRAE 55 in non-western regions, insulation data for such clothing is required. In the present project, ASHRAE 1504-RP, such data was collected for a range of non-western clothing types. Four different thermal manikins (male and female shapes) in three different laboratories (UK, Sweden and China), were used to determine the clothing insulation values of 52 clothing configurations. These fifty two configurations were also tested for the effects of air velocity on insulation and forty three were tested for the effects of posture (sitting) and walking. The observed reductions in insulation for both air velocity and walking are higher than those presented in the literature for western ensembles, emphasizing the need for these new data. This effect is most likely related to more open weave fabrics and loose fit designs. Similarly the relation of the clothing surface area factor to intrinsic clothing insulation was different from that published for western clothing. Prediction equations for the clothing surface area factor fcl, based on the new data only had limited predictive power, which however was also the case for those obtained in the past for western clothing. This issue seems to be commonly overlooked, as the use of these prediction equations is widespread. It has to be concluded that reliable fcl values can only be obtained when these are actually measured as in the present work. Having said this, the concept of the fcl factor for the non-western clothing may not work in the first place, as the wide falling robes and gowns do not match the cylindrical clothing and air layer model on which the fcl concept is based. The results provide an extensive database of insulation values of non-western clothing styles in different wear configurations, in different air velocities, postures and movement. As such this is expected to be a valuable addition to ASHRAE 55 and ISO 7730 and ISO 9920. In addition, data obtained on the insulation of individual body parts can be used by CFD modelers to incorporate realistic insulation data in their models.

A comparison of suit dresses and summer clothes in the terms of thermal comfort

Abstract: Fanger’s PMV equation is the result of the combined quantitative effects of the air temperature, mean radiant temperature, relative air velocity, humidity, activity level and clothing insulation. This paper contains a comparison of suit dresses and summer clothes in terms of thermal comfort, Fanger’s PMV equation. Studies were processed in the winter for an office, which locates in Ankara, Turkey. The office was partitioned to fifty square cells. Humidity, relative air velocity, air temperature and mean radiant temperature were measured on the centre points of these cells. Thermal comfort analyses were processed for suit dressing (Icl = 1 clo) and summer clothing (Icl = 0.5 clo). Discomfort/comfort in an environment for different clothing types can be seen in this study. The relationship between indoor thermal comfort distribution and clothing type was discussed. Graphics about thermal comfort were sketched according to cells. Conclusions about the thermal comfort of occupants were given by PMV graphics.

Field Study for Prediction and Evaluation of Thermal Comfort in Residential Buildings in the Equatorial Hot-Humid Climate of Malaysia

Abstract: An extensive field study has been carried out in non-air-conditioned residences in Kota Kinabalu city, in Malaysia for the prediction and evaluation of the effect of the indoor thermal environment on occupants' thermal comfort. A total of 890 responses over one year were gathered. The hot-humid indoor climates of the surveyed buildings have been described and analyzed in terms of air temperature, globe temperature, relative humidity, wind velocity. The clothing insulation ensemble and metabolic rate of the occupants were also characterized. In the aim to assess the comfort temperature in residential buildings in the hot-humid tropics, each analyzed variable was thoroughly compared with the results of two field studies located in the hot-humid tropics, one conducted in Jakarta by Feriadi and Wong [1] and the second in Singapore by de Dear et al. [2]. Multiple and stepwise regressions were applied for the selection of the independent variable for neutral temperature prediction. Air temperature was chosen as an index for the indoor thermal comfort. The comfort temperature was determined using various approaches. The predicted temperature was found to be nearly 30 °C regardless of the adopted approach. The indoor comfort temperature was close to the recorded mean indoor air temperature of all responses having a difference of about 0.7 °C. The mean and the recorded indoor range temperatures seem to have effect in the prediction of comfort temperature.

Seasonal distribution of comfortability: a regional based study over kalyani, west bengal, india

Abstract: Seasonal changes of weather parameters are the factors in urban environments which affect thermal comfort. It was reported that solar radiation may change the ambient temperature upto 4°C. Annual variation of temeprature and global radiation follow similar pattern. Object of our work is to point out the seasonal distribution of thermal stress over Kalyani. Thermohygrometric index, Wet bulb globe temperature and Relative strain index are estimated for the period 1994 to 2012 with some data gap. WBGT and RSI are widely used for outdoor workers. A regional based scale of WBGT and RSI are developed with reference to THI over Kalyani. However an integrated approach including the behavioral adjustment and clothing insulation of a person along with other parameters to compute stress indices may give better results to identify zone of thermal comfort.