Clothing , insulating value

Environmental Conditions. The last area of discussion concerns those studies that emphasize environmental factors indoors and their interrelationship with clothing. Fanger s multivariate equation for predicting thermal comfort indoors, which he defines as thermal neutrality, is based on statistical analysis of 1,300 Danish and American subjects and consists of six parameters metabolic activity of occupants, clothing insulative value (clo), air temperature, mean radiant temperature, relative humidity, and air velocity ( 8, TjO An instrument based m these parameters and the statistical analysis is available (Figure 2) a reading for the parameters is integrated and the percent of occupants satisfied with the thermal environment is displayed. 

Ideally, an audit system would be broad enough to cover any task in any industry, would provide highly detailed andysis and recommendations, and would be applied rapidly. Unfortunately, the three variables of breadth, depth, and application time are likely to trade off in a practical system. Thus a thermal audit (Parsons 1992) sacrifices breadth to provide considerable depth based on the heat balance equation but requires measurement of seven variables. Some can be obtained rapidly (air temperature, relative humidity), but some take longer (clothing insulation value, metabolic rate). Conversely, structured interviews with participants in an ergonomics program (Drury 1990a) can be broad and rapid but quite deficient in depth. 

Clothing affects heat and moisture loss. Increasing the thickness or number of layers of clothing increases its insulating capability and reduces body heat loss. Clothing insulation is usually described with the do unit. Originally, t do was defined as the thermal resistance necessary for comfort while sedentary in a uniform still air environment of 21 °C. In conventional SI nomenclature I do has a thermal resistance of 0.155 K m-/W. Some ensembles do values and associated comfort temperatures are shown in Fig. 5.4. 

Some clothing item do values are listed in Table 5.4. For example, the do value of a person wearing a thin shirt, thin trousers, underwear, shoes, and socks estimated by this method would be 0,17 + 0.25 + 0.05 + 0.05 = 0.52 do. If the person were to add a T-shirt under the shirt, the clothing insulation would be expected to increase to 0.6 do. 

Optimum comfort would be in the center of each zone. Moving away from the center, some people would be expected to have thermal sensations approaching - 0.5 and -i-0.5 at the cooler and warmer ET borders. The zones of Fig. 5.7b are for sedentary or slightly active ( M 1.2 met) people. If the activity level is higher than that, then the ET" line borders can be shifted about 1.4 K lower per met of increased activity. Similarly, if the clothing is different than the 0.9 and 0.5 do vales of Fig. 5.7a, the temperature boundaries can be decreased about 0.6 K for each 0.1 do increase in clothing insulation. Another, similar way to adjust the comfort zone for both different activity levels and do values is to shift the zone centered on the optimum temperature at... 

Target values for thermal conditions at different design stages must also be considered. One example, for a scenario similar to regular office work, is shown in Table 8.2. The activity level and clothing insulation of the workers must always be taken into consideration when target values are chosen. Different target values other than the ones used in this table could be required, for example, for very cold and very hot and humid environments. 

Sports clothing consists of different materials that have physical properties that interact with the human body. The first property is the insulation value. It can be measured using a hot plate (Mohammadi et al., 2003). The thermal resistance of... 

CLO n. A unit of thermal resistance. The insulation needed to keep an individual producing heat at the rate of 58 W/m comfortable of 21°C air temperature with air movement of 0.1 m/s. One do is roughly equal to the insulation value of typical indoor clothing. 

Clothing slows the rate of heat transfer between the body and the environment. In most cases clothing provides insulation to slow the loss of heat from the body. Various fabrics have different insulation values. 

TABLE 18-2 Insulation Value of Different Clothing Assemblies TABLE 18-3 Approximate Insulation Value of Air Film at Different Air Speeds ... 

A do is the unit of measure for the insulation value of a clothing assembly. There are methods for determining the do values of clothing assemblies. Controlled laboratory procedures involve placing a clothing assembly on a heated manikin and making measurements. Table 18-2 provides do values for some clothing assemblies. 

The available insulation is made up of the insulation value of the clothing assembly plus a film of still air at the outer surface of the clothing. 

There is a unit of insulation value for clothing known as the do , which is actually 0.155°C m AV. Some values are shown in Table 8.10. 

In a cold environment, plant personnel should be provided with adequate insulative clothing and shelter. Figure 4-10 plots the tolerance of individuals to lower temperatures based on the insulative value (do) of their protective... 

Only the results for the head and abdomen parts are presented here as the output values, for simphc-ity. It was considered that these parts have higher significance in terms of occupational comfort. Although the measurements were made at three levels head, abdomen and ankles, the abdomen was selected to be the covered part in this study, as in terms of numerical equations no distinctions were considered between the abdomen and ankles concerning the insulation. To test the effect of the cloth insulation, the results of the head were also presented as a naked part. 

Perkins, R.M., 1979. Insulative values of single-layer fabrics for thermal protective clothing. Text. Res. J. 49 (4), 202-205. 

For clothing assemblies, more information is needed on the insulative (clo) values of representative fiber/fabric combinations available to consumers. These clo values may then be related to thermal comfort at conservative thermostat temperatures using instruments such as the Comfytest, which has the capability of evaluating the six parameters of Fanger s thermal comfort equation (7U). 

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