Search results

The purpose of this paper is to present the determination of human thermal comfort with wearing clothes, with different water vapor permeability. Currently, the predicted mean vote (PMV) equation is widely used to determine thermal sensation scales of human comfort. However, moisture permeability of clothes has been not taken in account where the heat is lost from a human body due to water vapor diffusion through clothes.

In this study, the heat loss is derived based on the real structure of textiles, causing water vapor pressure difference between air on skin and ambient air. The PMV equation is modified to differentiate a thermal sensation scale of comfort although patterns of clothes are the same. Interview tests are investigated with wearing clothes from three types of textiles: knitted polyester, coated nylon–spandex, and polyurethane, under various air conditions.

The moisture permeabilities of knitted polyester, coated nylon–spandex and polyurethane are 16.57×10⁻⁹ kg/m² s•kPa, 9.15×10⁻⁹ kg/m²•s•kPa and 2.99×10⁻⁹ kg/m²•s•kPa, respectively. The interviews reveal that most people wearing knitted-polyester clothes have the greatest cold sensations under various air conditions since moisture permeability is the highest, compared to coated nylon–spandex, and polyurethane leather. Correspondingly, the predicted results of the modified PMV equation are close to the actual mean votes of interviewees with a coefficient of determination R²=0.83. On the other hand, the coefficient of determination from the predicted results of the conventional PMV equation is significantly lower than unity, with R²=0.42.

In practice, this quantitative determination on human thermal comfort gives some concrete recommendations on textile selection of clothes for acceptable satisfaction of thermal comfort under various surrounding conditions of usage.

The modified PMV equation effectively determines human comfort on a thermal sensation scale due to the moisture permeability of clothes. To make generic conclusion, experimental results of additional three textiles, such as plain weave/lining polyester, knitted spandex, and open structure polyester, are reported. They confirm that the modified PMV equation effectively determines human comfort on a thermal sensation scale due to the moisture permeability of clothes.

The ever-increasing demand and consumption of energy and the effects of global warming with its long-term comrade, climate change, is obvious today than ever before. In today’s world, naturally-ventilated buildings hardly provide the satisfaction that occupants need and wish for. It’s on this backdrop that the study aims to investigate how responsive buildings on the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana campus are to its warm humid climate and assess students thermal comfort levels.

Quantitative approach was adopted for the study. Empirical investigation was carried out using the survey approach. In total, 14 buildings (offices, classrooms and halls of residences) were assessed using the Mahoney Tables. Again, subjective thermal perceptions of occupants in the halls of residences was sought. A total of 214 valid questionnaires were used for the analysis.

Adaptive principles like the Mahoney Tables are not followed in recent years. Even where these principles have been followed, indoor spaces were still found to be uncomfortable. In total, 58 per cent of the occupants in all the three halls of residence voted in the comfort band: an indication unacceptable sensations. Warm sensation votes (44 per cent) was more than cool sensation votes (29 per cent). In warm sensation, 39 per cent of the subjects preferred cooler environment. The occupants felt that opening windows and the use of fans could keep them comfortable. Moreover, 48 per cent of the subjects voted that their fans and windows were effective.

The papers contribution to the body of knowledge is the provision of empirical evidence in the field of adaptive designs and thermal comfort. There is a strong indication from the results that human activities in terms of blatant disregard for laid down design principles coupled with the worsening situation of global warming is making interior spaces ever uncomfortable.

The purpose of this paper was to investigate whether small holes in an impermeable patch at the wrist improve perceived comfort during exercise.

Nine male participants participated in this study. During the experiment, participants cycled 60 W in a hot room (35°C, 30 percent relative humidity) while an impermeable 20 cm² patch was located on the ventral side of one wrist and at the same time a patch of identical shape with 5 mm diameter holes (17.7 percent uncovered) on the other wrist. The participants could not see the patches. Participants were forced to choose which patch they perceived as more comfortable. Chest and arm skin temperature, thermal comfort, thermal sensation and wetness perception were assessed.

Participants preferred 5 mm holes over no holes (p=0.017). Chest skin temperature (p=0.018) but not arm skin temperature correlates with this preference. Thermal comfort, thermal sensation and wetness perception did not differ significantly between patches. It is concluded that patches with 5 mm holes are preferred over impermeable patches during work in the heat in particular when the torso skin is warm.

The wrist is a preferred location for smart wearables. Generally, wrist bands are made of air-impermeable materials leading to sensation of wetness and discomfort. This study has shown that manufacturers should consider to make small holes in their wrist bands to optimize wearing comfort.

Current measurement methods for fabric comfort attributes generally suffer from either complicated testing processes and intricate measuring equipment or partial evaluation objectives and thus are difficult for effectively evaluating multidimensional human perceptions towards the comprehensive comfort of fabrics. The purpose of this paper is to develop a facile test device, namely fabric comfort tester, to achieve a comprehensive evaluation of human sensations in terms of sensorial, thermal and acoustic comfort in clothing.

The prototype of the designed device was introduced, which enables a simultaneous test for multiple physical and mechanical properties of fabrics based on a force sensor and a set of infrared sensors via constructing multi-deformation states of the measured fabrics. Eleven measurement indices extracted from the measurement curves are defined and interpreted based on correlation analysis. A series of regression models are developed by relating the measurement indices with subjective evaluation results and validated by a set of independent samples.

Human perceptions of sensorial, thermal and acoustic comfort in clothing can be predicted by the measured physical indices and the designed test device with the developed regression models provides an alternative method to characterize the fabric comfort attributes effectively.

The work develops a novel device for objective evaluation of fabric comfort properties by a simultaneous test, integrating the mechanical measurement with thermal test and thereby filling the gap between the existing evaluation methods and practical requirements for the digitalization of fabric comfort in present textile and garment trade.

The aim of this study is to investigate wearing comfort of summer work uniforms judged by construction workers.

A total of 189 male construction workers participated in a series of wear trials and questionnaire surveys in the summer of 2014. They were asked to randomly wear two types of work uniforms (i.e. uniforms A and B) in the two-day field survey and the subjective attributes of these uniforms were assessed. Three analytical techniques, namely, multiple regression, artificial neural network and fuzzy logic were used to predict wearing comfort affected by the six subjective sensations.

The results revealed that fuzzy logic was a robust and practical tool for predicting wearing comfort in terms of better prediction performance and more interpretable results than the other models. Pressure attributes were further found to exert a greater effect than thermal–wet attributes on wearing comfort. Overall, the use of uniform B exhibited profound benefits on wearing comfort because it kept workers cooler, drier and more comfortable with less work performance interference than wearing uniform A.

The findings provide a fresh insight into construction workers’ needs for work clothes, which further facilitates the improvement in the clothing tailor-made design and the enhancement of the well-being of workers.

Relationships have been investigated between subjective pressure sensation and objective pressure measured, for knit garments of different sizes and fabrics with different extensibilities. Fechner's logarithmic law is used to investigate the relations. Equations are obtained for describing the Psychophysical mechanism of clothing pressure perception under certain conditions. Objective pressure measuring had high predictive power with regard to subjective pressure sensation only under those conditions. Wearing pressure comfort has a negative correlation with feelings of fetter, scratchy, heavy and pressure, and has a poor correlation with feelings of softness and smoothness. Using factor analysis with principal factor solutions and rotated by the Varimax method, we obtained factor matrices.

This study aims to investigate the heat transfer mechanism of the uniforms used by people working in hot, humid and windy environments. Furthermore, the effectiveness of an opening structure added to the armpit of the uniforms in improving thermal comfort was comparatively examined.

A set of uniforms was tested with the opening at the armpit alternatively zipped or unzipped. Thermal manikin and human tests were performed in a climatic chamber simulating the specific environmental conditions, including wind speeds at four levels (0.15, 0.5, 2, 4 m/s) and relative humidities at two levels (50 and 85%). Static and dynamic thermal insulations of clothing (I_T) were examined by the thermal manikin tests. The human bodies' thermal responses, including heart rates (HR), eardrum temperatures (T_e), skin temperatures (T_sk) and subjective perceptions, were given by the human tests.

Special mechanisms of heat transfer in the specific uniforms used in tropical monsoon climates were revealed. Reductions on I_T were caused by the movement of the human body and the environmental wind, and the empirical equations would underestimate this reduction. The opening at the armpit was able to prompt more heat transfer under dynamic condition, with reducing the I_T by 11.8%, lowering the mean T_sk by 0.92°C, and significantly improving the subjective perceptions (p < 0.05). The heat exhaustion was alleviated with lowering the T_e by 0.32°C.

This study managed to improve the thermal performance of uniforms for workers under unforgiving conditions. The evaluation and design methods introduced by this study provided practical guidance for similar products with strict dress codes and cost control requirements based on the findings from thorough product tests and analysis.

The preservation of historic urban centres prevents anarchic development of the city and ensures a harmonious evolution of the urban form. It also improves the quality of life in the context of climate and environmental change. Morphological and geometric indicators of the urban fabric are key parameters in the formation of external microclimates. They provide a positive effect on the thermal comfort of pedestrians. The objective of this work is to study the impact of the site morphology on the external microclimate and to understand the relationship between the subjective perception and the objective quantification of the thermal environment. The result of this study has allowed us to propose solutions for the creation of a microclimate favourable to the appropriation of outdoor spaces. The authors finally propose guidelines for the design and rehabilitation of the historic site based on the establishment of links between the site's configuration, microclimatic conditions and users' perceptions.

Part of this study included the analysis of the microclimate of the historic “Bab El Hadid” district of the City of Tlemcen, by developing a questionnaire survey and a numerical simulation validated by measurements of the microclimate the authors made on site. To complete this task, the authors applied the Envi-met 4.1 model during the coldest month of the winter and the hottest month of the summer. Urban parameters are represented at different measurement points characterised by a variability of the sky view factor (SVF).

The results presented in terms of average expected the predicted mean vote (PMV) voting, solar access and air temperature. They show that thermal conditions are directly related to the SVF, the height/width ratio (H/L) of streets as well as the orientation of urban canyons. The points located in the streets facing North–South, present an acceptable performance. Streets shaded by trees with a canyon aspect ratio of between 1.18 and 1.70 reduce heat stress in outdoor spaces. The PMV models discussed provide information on the most appropriate locations for pedestrians. The authors have proposed urban orientations that could limit unfavourable conditions in outdoor spaces. They are useful for architects and urban planners in the design and rehabilitation of historic centres.

In Tlemcen, the microclimate is not taken into account in the design and rehabilitation of urban fabrics. For this specific purpose, the authors want to stress in the research the importance of safeguarding urban heritage through the renewal of the old city and the bioclimatic rehabilitation of its urban spaces.

In order to study the static and dynamic comfort of tight sportswear in winter, the subjective comfort was aimed to be evaluated by collecting sensory data such as humidity feeling, cold feeling and other perceptions. In this paper, the experiment was divided into standing, squatting, jumping, jogging, walking and so on.

Through particle swarm optimization-cuckoo search model, the sensory factors that affect the overall comfort were optimized, and it was found that there were great differences in the overall comfort factors under different motions. Then, analytic hierarchy process was used to sort the optimized sensory indicators in each experimental stage, and the influence degree of sensory indicators was studied. Finally, by the long short-term memory (LSTM) model, taking comfort senses of standing, squatting, jumping and jogging as input parameters, and regarding comfort senses of walking, lifting legs and resting as output parameters, the prediction model was founded.

The results showed that there were certain differences between the prediction value and the real subjective evaluation value, but most of the predicted values were consistent with the real values on the sensory level, and the overall prediction level was good, which meant that the LSTM model had more accurate prediction ability for subjective evaluation and could be extended to other sports.

The research results could provide scientific methods for the design of tight-fitting sportswear in winter.

The purpose of this paper is to evaluate the effects of intermittent and continuous heating protocols using graphene-heated clothing and identify more effective body region for heating in a cold environment.

Eight males participated in five experimental conditions at an air temperature of 0.6°C with 40 percent relative humidity: no heating, continuous heating the chest, continuous heating the back, intermittent heating the chest, and intermittent heating the back.

The results showed that the electric power consumption of the intermittent heating protocol (2.49 W) was conserved by 71 percent compared to the continuous protocol (8.58 W). Rectal temperature, cardiovascular and respiratory responses showed no significant differences among the four heating conditions, while heating the back showed more beneficial effects on skin temperatures than heating the chest.

First of all, this study was the first report to evaluate cold protective clothing with graphene heaters. Second, the authors provided effective intermittent heating protocols in terms of reducing power consumption, which was able to be evaluated with the characteristics of fast-responsive graphene heaters. Third, an intermittent heating protocol on the back was recommended to keep a balance between saving electric power and minimizing thermal discomfort in cold environments.