Contribution of garment fit and style to thermal comfort at the lower body

Objective multi-criteria decision-making for optimal firefighter protective clothing size selection

Objectives. Addressing the prevalent issue of size misfits in large-scale issued firefighter uniforms due to diverse and complex body morphologies, this article presents an objective method for intelligent garment sizing matching without subjective weighting. Methods. The method employs criteria importance through inter-criteria correlation (CRITIC) and the catastrophe progression method (CPM) for more accurate and reliable sizing. Traditional methods, reliant on limited indicators such as height and chest girth and often subjectively determined by experts, are prone to reliability concerns. Matching decisions made based on our approach are evidence-based, transparent and reproducible, thus minimizing subjectivity and expert intervention. Results. A case study of 388 cases validates the method's efficacy in providing garment size recommendations, surpassing traditional experience-based approaches by reducing subjective bias. Conclusion. Despite some differences, the optimal alternatives for examinees are almost consistent across the different methods. Compared with traditional subjective weighting methods, this method has potential advantages in situations such as large-scale matching of firefighter protective clothing where individual customization or direct try-on is not feasible.

Analysis of glove local microclimate properties for various glove types and fits using 3D scanning method

Due to their geometry and thermal physiology, hands are most vulnerable to cold weather injuries and loss of dexterity. Gloves are the most common for hand protection during exposure to extreme thermal and hazardous environments. Although glove microclimate properties such as area factor, air gap thickness, and contact area play a significant role in thermal protection, identifying local (at individual hand segments) glove microclimate properties is still a research gap. For the first time, the glove-microclimate properties for 16 hand segments at high spatial resolution were analyzed by employing state-of-the-art hand-held 3D scanner and post-processing techniques for different glove types. Our results clearly indicate that the glove area factor for distal phalanges is significantly higher (by 49.8 %) than that for other hand segments, which increases the heat transfer from distal phalanges. In contrast, average air gap thickness was relatively uniform across all hand segments. The glove type had a pronounced effect on glove microclimate properties, e.g., bulky and heavy cold weather protective gloves had a larger average air gap thickness and glove area factor. Regression models are also developed to estimate the glove microclimate properties from simple measurement (i.e., ease allowance). Overall, this study provides essential information for the design and development of protective gloves that can help improve safety, comfort, and dexterity. Methods and mathematical models developed in this study also contribute to facilitating extremity (e.g., hand) focused thermoregulation modeling, hazard simulation, injury prediction, ergonomic design, optimum performance (dexterity and tactility) along with thermal protection.

Garment size effect of thermal protective clothing on global and local evaporative cooling of walking manikin in a hot environment

Evaporative cooling is the critical heat dissipation mechanism for working individuals wearing thermal protective clothing in hot environments. However, until now, there is no knowledge on garment size design for evaporative cooling optimization, especially when the human body is in movements. In this study, to understand the dynamic effect of garment size on evaporative cooling, we performed experiments on a sweating thermal manikin with seven garment sizes and three walking speeds. The evaporative cooling of global and local manikin body with this wide range garment sizes was present. Results demonstrated that the effect of garment size on evaporative cooling depended on the walking speed. At lower walking speeds, the global evaporative cooling tended to decrease with greater garment size, while at higher walking speeds, the global evaporative cooling tended to increase with greater garment size. Similarly, according to effects of garment size on local evaporative cooling, body segments could be divided into three categories for evaporative cooling optimization. Further, we analyzed factors which influenced the positive effect of walking speed on the evaporative cooling. Results showed that, for most cases, the increase of evaporative cooling caused by walking showed positive linear relationship with the garment size. Further increase of walking speed led to a greater increase rate of evaporative heat loss for body segments with the small air gap. This study provides insights into clothing local characteristics of evaporative cooling with different garment sizes under dynamic conditions and may help clothing design to optimize the evaporative cooling of working individuals in hot environments.

Evaluation of Thermal Properties of 3D Spacer Technical Materials in Cold Environments using 3D Printing Technology

Novel materials have been recently developed for coping with various environmental factors. Generally, to improve the thermal comfort to humans in cold environments, securing an air layer is important. Therefore, this study analyzed the thermal properties of 3D spacer technical materials, 3D printed using thermoplastic polyurethane, according to the structural changes. Four 3D spacer technical material structures were designed with varying pore size and thickness. These samples were moved into a cold climate chamber (temperature 5 ± 1 °C, relative humidity (60 ± 5)%, wind velocity ≤0.2 m/s) and placed on a heating plate set to 30 °C. The surface and internal temperatures were measured after 0, 10, 20, and 30 min and then 10 min after turning off the heating plate. When heat was continuously supplied, the 3D spacer technical material with large pores and a thick air layer showed superior insulation among the materials. However, when no heat was supplied, the air gap thickness dominantly affected thermal insulation, regardless of the pore size. Hence, increasing the air gap is more beneficial than increasing the pore size. Notably, we found that the air gap can increase insulation efficiency, which is of importance to the new concept of 3D printing an interlining.

Local clothing thermal properties of typical office ensembles under realistic static and dynamic conditions

An accurate local thermal sensation model is indispensable for the effective development of personalized conditioning systems in office environments. The output of such a model relies on the accurate prediction of local skin temperatures, which in turn depend on reliable input data of the local clothing thermal resistance and clothing area factor. However, for typical office clothing ensembles, only few local datasets are available in the literature. In this study, the dry thermal resistance was measured for 23 typical office clothing ensembles according to EN-ISO 15831 on a sweating agile manikin. For 6 ensembles, the effects of different air speeds and body movement were also included. Local clothing area factors were estimated based on 3D scans. Local differences can be found between the measured local insulation values and local area factors of this study and the data of other studies. These differences are likely due to the garment fit on the manikin and reveal the necessity of reporting clothing fit parameters (e.g., ease allowance) in the publications. The increased air speed and added body movement mostly decreased the local clothing insulation. However, the reduction is different for all body parts, and therefore cannot be generalized. This study also provides a correlation between the local clothing insulation and the ease allowance for body parts covered with a single layer of clothing. In conclusion, the need for well-documented measurements is emphasized to get reproducible results and to choose accurate clothing parameters for thermo-physiological and thermal sensation modeling.

Local air gap thickness and contact area models for realistic simulation of human thermo-physiological response

To evaluate the quality of new energy-saving and performance-supporting building and urban settings, the thermal sensation and comfort models are often used. The accuracy of these models is related to accurate prediction of the human thermo-physiological response that, in turn, is highly sensitive to the local effect of clothing. This study aimed at the development of an empirical regression model of the air gap thickness and the contact area in clothing to accurately simulate human thermal and perceptual response. The statistical model predicted reliably both parameters for 14 body regions based on the clothing ease allowances. The effect of the standard error in air gap prediction on the thermo-physiological response was lower than the differences between healthy humans. It was demonstrated that currently used assumptions and methods for determination of the air gap thickness can produce a substantial error for all global, mean, and local physiological parameters, and hence, lead to false estimation of the resultant physiological state of the human body, thermal sensation, and comfort. Thus, this model may help researchers to strive for improvement of human thermal comfort, health, productivity, safety, and overall sense of well-being with simultaneous reduction of energy consumption and costs in built environment.

An integrated approach to develop, validate and operate thermo-physiological human simulator for the development of protective clothing

Following the growing interest in the further development of manikins to simulate human thermal behaviour more adequately, thermo-physiological human simulators have been developed by coupling a thermal sweating manikin with a thermo-physiology model. Despite their availability and obvious advantages, the number of studies involving these devices is only marginal, which plausibly results from the high complexity of the development and evaluation process and need of multi-disciplinary expertise. The aim of this paper is to present an integrated approach to develop, validate and operate such devices including technical challenges and limitations of thermo-physiological human simulators, their application and measurement protocol, strategy for setting test scenarios, and the comparison to standard methods and human studies including details which have not been published so far. A physical manikin controlled by a human thermoregulation model overcame the limitations of mathematical clothing models and provided a complementary method to investigate thermal interactions between the human body, protective clothing, and its environment. The opportunities of these devices include not only realistic assessment of protective clothing assemblies and equipment but also potential application in many research fields ranging from biometeorology, automotive industry, environmental engineering, and urban climate to clinical and safety applications.