Laboratory assessment of cold weather clothing

An overview of laboratory tests for cold weather clothing is provided starting from physical measurements on fabrics, and physical measurements on whole garments using thermal manikins. This is extended to human wear trials and climatic chamber experimentation. Insulation and vapour resistance are considered the most relevant parameters followed by wind and water proofness and moisture absorption properties. The use of test participants in wear trials is considered regarding the information provided by such tests. Tests for innovative fabrics (heated, variable insulation, phase change materials) are discussed. Finally testing of sleeping bags is considered

Moisture accumulation in sleeping bags at subzero temperatures - effect of semipermeable and impermeable covers

Because subzero temperatures are expected to affect the vapor resistance of micro porous membranes, the effect of using semipermeable and impermeable rain covers for sleeping bags on moisture accumulation in the bags during 6 days of use at -7°C is investigated. Moisture accumulation is related to the vapor resistance of the materials. The best semipermeable material gives the same moisture build-up as no cover. Semiperme able cover materials are effective at reducing moisture accumulation in sleeping bags at moderate subzero temperatures

Thermal conditions measurement

Thermal conditions measuremen

Temperature regulation, heat balance and climatic stress

This paper discusses human thermoregulation and how this relates to health problems during exposure to climatic stress. The heat exchange of the body with the environment is described in terms of the heat balance equation which determines whether the body heats up, remains at stable temperature, or cools. Inside the body the thermoregulatory control aims at creating the right conditions of heat loss to keep the body temperature stable. In the heat the main effector mechanism for this is sweating. The heat balance is affected by air temperature, radiant temperature, humidity and wind speed as climatic parameters and by activity rate, clothing insulation and sweat capacity as personal parameters. Heat tolerance is discussed in the light of personal characteristics (age, gender, fitness, acclimatisation, morphology and fat) indicating age and fitness as most important predictors. Heat related mortality and morbidity are strongly linked to age

Metabolic rate and clothing insulation data of children and adolescents during various school activities

Data on metabolic rates (n=81) and clothing insulation (n=96) of school children and adolescents (A, primary school: age 9-10; B, primary school: age 10-11 year; C, junior vocational (technical) education: age 13-16 (lower level); D, same as C but at advanced level; and E, senior vocational (technical) education, advanced level: age 16-18) were collected (Diaferometer, Oxylog, Heart Rate derivation) during theory-, practical- and physical education- lessons. Clothing insulation was calculated from clothing weight, covered body surface area, and the number of clothing layers worn. Clothing insulation was found to be similar to that expected for adults in the same (winter) season, with minimal variation with age or school type (0.9 to 1.0 clo; 1.38 clo where coverall was worn), but more variation within groups (coefficient of variation 6-12%). Metabolic rate values (W.m-2) were lower than expected from adult data for similar activities, but are supported by other child data. The results of this study can be used to establish design criteria for school climate control systems or as general data on energy expenditure for children and adolescents. The results emphasise the need for specific child data and shows the limited value of size-corrected adult data for use in children

Benchmarking functionality of historical cold weather clothing: Robert F. Scott, Roald Amundsen, George Mallory

Replica clothing as worn by Robert F. Scott and Roald Amundsen in their race to be the first on the South Pole and by George Mallory in his ascent of Everest was tested for thermal insulative properties. These were benchmarked against modem day explorer clothing. Results are discussed in terms of insulation, insulation per weight, and wind protection. Further the effects of clothing on energy consumption were considered as well as the effect of altitude on insulation and energy consumption. The biggest advantage of modem clothing seems to be its lower weight. Scott's clothing resulted in extra energy usage for the wearers and provided less insulation than Amundsen's, though sufficient while active. The Mallory clothing had a low energy requirement due to the incorporation of 'slippery' silk layers. Its insulation would have been sufficient down to -30°C in low wind. If wind were to increase, the clothing would however not have provided the required insulation

Temperature regulation and technology

The ability to thermoregulate typically decreases with age. This is strongly related to decreases in physical fitness and increases in the incidence of disabilities with ageing. The reduced thermoregulatory capacity leads to increased mortality and morbidity. Heat stroke, hypothermia, increased number of falls, and in home drowning are some of the problems that are identified to be associated with this reduced thermoregulatory capacity. As solution, using advanced technology in terms of full climate control is suggested as a short-term solution for the ill or infirm only. For longer-term solutions, limited climate control (taking away peak loads), improved housing design and proper use of modern clothing are proposed to alleviate the problems. For the clothing, better education of the elderly in the possible advantages of high tech clothing materials is proposed, as well as education to their proper way of use. Manufacturers should consider adjusting their marketing policies to include the elderly in their targeted groups

Clothing heat exchange models for research and application

The regulated exchange of heat from the human body to the environment is essential in human survival. This exchange is adjusted by our physiological response mechanisms. We are able to sweat profusely to cool the body in exercise and heat exposure, and are able to fine-tune our body temperatures in moderate environments through variations in skin circulation. In slightly cool environments, we reduce blood flow to our extremities and skin and use our fat layer insulation to conserve central body temperature. We can increase our heat production by shivering and can create a small insulating air layer around our skin by pilo-erection. However, when temperature goes down further, we cannot sustain our body temperature in the long run without behavioural adjustments that include putting on clothing or using heated dwellings. In this context, clothing has allowed mankind to expand its habitat around the world and has had a positive influence on its development. Today, clothing is worn for various reasons. Apart from its functional aspects (insulation, protection), it has a strong cultural and social aspect as well. The latter are on occasion counterproductive in terms of the first. A business suit for instance is hardly functional in a tropical climate, nor is a ladies evening dress in a cold environment. Also, when the function of the clothing is not only protection against heat or cold, as e.g. is the case with chemical protective clothing, the barriers introduced in the clothing to achieve the required protection can cause a conflict between the protective function of the clothing and the thermal functioning of the body. These conflicts can lead to discomfort, but also to physical strain and in extreme cases can put the person at risk from heat or cold injury or illness

Comparison of different tracer gas dilution methods for the determination of clothing ventilation

Clothing vapour resistance (CVR) is an important parameter when evaluating the impact of the ambient workplace climate on the worker. It determines the worker’s ability to lose heat (sweat evaporation) to the environment and thereby to control his or her body temperature. This impact can be in terms of stress (heat or cold) or comfort. These evaluations are used for the classification of existing workplaces, as well as for the design of new workplaces (for example building climate control systems) and thus affect the issue of health and efficiency in the workplace. As determination of CVR is currently quite complex, very time consuming and costly, alternative methods need to be developed. Deduction of CVR from clothing microclimate ventilation measurements is such an alternative (1). Two methods for the measurement of clothing ventilation have been developed: one by Lotens and Havenith (2) in the Netherlands and one by Crockford et al (3,4), which was further developed in Loughborough for the UK Ministry of Defence by Bouskill (5). Both methods for measuring clothing ventilation are currently in use in different laboratories, however without ever being directly compared. For this paper, it was chosen to start with a practical comparison of these methods to each other and a validation of both

Ethnic differences in thermal responses and comfort sensation between Japanese and Caucasian young males under a temperate environment

This study has been made to examine ethnic differences in thermal responses and human thermal comfort sensation between Japanese and Caucasians under a temperate environment. Young healthy Japanese and Caucasian males voluntary participated in the present study. In the study, they firstly kept a rest condition and walked on a treadmill in the exercise condition. Japanese showed significantly higher mean skin temperature than Caucasian during a whole period of the experiment. Although the water vapour pressure over the skin surface during the rest was statistically slightly higher in Caucasian than in Japanese, calculated evaporation rate from the body surface in Japanese was significantly larger than that in Caucasians. This was because the temperature difference between the skin surface and the environment was larger in Japanese than in Caucasians. Calculated evaporation rate from the body surface during the exercise was found to be significantly larger in Japanese than in Caucasian because both of temperature and water vapour pressure of the skin surface showed remarkably higher values in Japanese than in Caucasians. Thermal comfort limit was discussed using skin wettedness based on linearity between the voted thermal comfort sensation and skin wettedness. The thermal comfort limits of the whole body were 0.39 ±0.05 in Japanese, and O.34 .± 03 in Caucasians. The thermal comfort limit in Japanese was found to be statistically equal to that in Caucasian