The physical mechanisms of the perception of dampness in fabrics

1. 1. The detection of dampness in hygroscopic materials has been investigated both by subjective tests and by the application of a model of the physical mechanisms involved.

2. 2. Subjects were asked to rate the degree of dampness of a range of materials of different moisture contents after a short period of contact with the inner forearm.

3. 3. Skin and fabric inner surface temperatures were recorded

4. 4. It was found that highly hygroscopic wool fabrics were perceived as being dryer and maintained a higher temperature at the skin surface than polyester, a less hygroscopic fabric, during fabric-skin contact.

5. 5. A physical model of the sorption/desorption process in hygroscopic materials has been developed from knowledge of fibre sorption kinetics and has been used to study the physical processes which take place at the skin-fabric interface during transient contact.

6. 6. These predictions agree well with the subjective responses and the measured temperatures.

Effect of fiber type and fabric moisture content on the hydration state of human stratum corneum

1. 1. The purpose of this study was to determine the effect of fiber type and fabric moisture content on SC hydration.

2. 2. Using three similarly constructed fabrics, six fabric type/moisture content combinations were selected.

3. 3. Fabric swatches were placed on both “normal” and “hydrated” volar forearm skin of five subjects for a specified period, then removed.

4. 4. Two minutes after removal, evaporative water loss (EWL) and skin temperature were measured.

5. 5. Data were analyzed using analyses of variance and Bonferroni t-tests.

6. 6. For normal skin, SC hydration generally increased as fabric moisture content increased. SC was significantly drier after being in contact with cotton swatches at regain than at the two moisture content levels above regain, and also under polyester swatches.

7. 7. For hydrated skin, hydration state was significantly lower under the cotton swatch at regain than at 38.6% moisture content or at saturation, but was not significantly different under the polyester swatch at regain or at saturation.

Dynamic heat and moisture transfer through multiple clothing layers

1. 1. The purposes of this study are to find out the arrangement effects on the vapor pressure gradient across the cotton–nylon double layer and to elucidate changes in the vapor pressure gradient when an additional third layer covers the double layer.

2. 2. Model tests for single, double and triple layer system and wear test for triple layer clothing were conducted.

3. 3. It was found that up to the second layer, dryness of innermost microclimate could be maintained when cotton faced the skin (C/N).

4. 4. However, when more permeable and hydrophobic third layer (UWF) covers the double layer, the microclimate of C/N is no longer drier than N/C.

5. 5. When nylon is exposed to the skin, a larger drop in vapor pressure across the first two layers occurred for both model and wear test.

6. 6. The innermost microclimate was not necessarily kept dry when the outermost layer dissipated more moisture due to the inefficient distribution of moisture.

Bed climate of Korean using ondol heating system

1. 1. To examine the influence of different bed conditions (ondol sleep, bed sleep on ondol with same bedding) of the Korean ondol traditional heating system on human response during sleep, bed climates and physiological responses such as skin and rectal temperatures, weight loss, body movement and subjective sensation were measured with 4 grown-up females as subjects while they were sleeping for 7 h.

2. 2. Bed climate: Temperatures under the mattress and inside the quilt were higher on ondol while temperatures on the mattress and humidity inside the quilt were higher on the bed.

3. 3. Rectal temperature was significantly higher on ondol; skin temperature showed no major differences in relation to bed conditions. The frequency of body movements had the highest correlation with bed climate of the parameters measured.

4. 4. Mattress weight decreased on ondol and increased on the bed.

5. 5. The frequency of body movements was significantly higher in ondol sleep.

6. 6. The subjects sensation showed difference on cushion sensation between the two types of bed condition.

7. 7. To obtain the same level of comfort on both ondol and bed sleeping conditions less thermal insulating value is needed for ondol sleep.

Transient response of the human-clothing system

1. 1. A transient clothing model which considers the effects of adsorption and thermal capacitance on the dynamic thermal response of clothing was developed.

2. 2. Moisture adsorption and desorption by the fabric are the major factors that affect the transient response of clothing.

3. 3. This moisture can come from evaporated sweat or from the environment.

4. 4. The clothing model was combined with a modified version of the two-node thermal model of the human body.

5. 5. The combined model shows that, during transients, the mix of latent and sensible heat flow from the skin may differ considerably from the corresponding heat flows from the clothing surface to the environment.

6. 6. The alteration of the heat flows can have a significant impact on the thermal response of the body by changing the sweat rate required to achieve the heat loss necessary to maintain thermal balance.

Responses of human skin temperature and thermal sensation to step change of air temperature

1. 1. The purpose of this paper is to clarify the non-linearity of the human physiological and psychological responses to step change of air temperature by impulse response analysis using Discrete Fourier Transformation.

2. 2. Experiments were conducted to investigate the effect of thermal transients on human responses.

3. 3. Experimental conditions were as follows: lowering air temperature from 30 to 20°C and raising air temperature from 20 to 30°C.

4. 4. The responses of local skin temperature on lowering air temperature from 30 to 20°C are not necessarily opposite to the responses found on raising air temperature from 20 to 30°C.

5. 5. From impulse response analysis using Discrete Fourier Transformation, skin temperature responses to the opposite air temperature change do not necessarily coincide with each other whenever the same temperature stimulus is occurred.

TLV in cold environments

1. 1. The risks encountered during cold exposure are general body cooling or local cooling of parts of th body.

2. 2. Measures of cold stress must account for the effects of climate, clothing and metabolic heat production on heat balance.

3. 3. The combinaed effect of air temperature, mean radiant temperature, humidity and air velocity determines the cooling power of the environment.

4. 4. The cooling power can be easily converted into a required insulation value (IREQ) for whole body heat balance.

5. 5. Extensive cooling of hands and feet may be a limiting factor, even when sufficient total insulation is provided. In addition the cooling effect of wind on unprotected skin must be considered.

6. 6. Recommendation regarding acceptable exposures can be expressed as lowest ambient temperatures and time limits as function of available protection and activity level, with due attention to both general and local effects.

Factors affecting the resistance to heat transfer provided by clothing

1. 1. This paper discusses the factors that affect the insulation and evaporative resistance provided by clothing.

2. 2. These include: fabric thickness and density, the amount of body surface area covered by garments, the evenness of the distribution of fabrics over the body surface, the increase in surface area for heat loss due to clothing, the looseness or tightness of fit, a person's body position (seated vs standing), body motion and wind.

Estimation of thermal sensation using PMV and SET under high air movement conditions

1. 1. Our previous experimental results showed the thermal sensation vote was much less than the values of PMV and SET^* at air velocities above 0.5 m/s.

2. 2. The method to modify SET^* is presented from the results of subjective experiments taking account of decrease in clo value of summer clothing and decrease in skin wettedness due to increased air velocity.

3. 3. Thermal resistance under increased air movement on a standard summer clothing ensemble was measured. Basic thermal insulation of the summer ensemble was reduced by 25% at air velocity of 1.0 m/s.

4. 4. Thirty-two subjects were exposed at operative temperatures of 27 and 30°C under 1 m/s air movement in order to determine the amount of skin diffusion. Measured evaporation heat loss from skin surface was much smaller at air velocity of 1 m/s than that predicted by SET^*.

5. 5. Estimated thermal sensation vote using modified SET^* agreed well with our previous experimental results under different air velocities for the same clothing.

Physiological and psychological thermal response to local cooling of human body

1. 1. In order to investigate the thermoregulatory responses to the non-uniform thermal environment of the human body, the effects of cooling 10 different body regions were compared by circulating cool water to the neck, breast, back, loin, upper-arms, lower-arms, hands, thighs, legs and feet, respectively. Tympanic temperature, regional (11 sites) and mean skin temperature, and the thermal sensations were measured during experiment in which 30 min local coolings were applied on 5 female students in a climatic chamber controlled at 30°C and 50% r.h.

2. 2. The skin temperature beneath the cooling pad decreased in the order of arms, legs, hands and feet, and trunk.

3. 3. The temperature drop was significantly correlated with the thermal sensation of the region itself.

4. 4. On the other hand, the tympanic temperature increased once by any local cooling. The increase of it was correlated with the change of the general thermal sensation.

5. 5. Results of principal component analysis of skin temperature showed that the peripheral cooling affected the skin temperature in the limited peripheral regions, while the effects of cooling of the breast and the back extended to both the central and peripheral.

Comparison of thermal responses with and without cold protective clothing in a warm environment after severe cold exposures

1. 1. Ten male students remained in a severely cold room (-25°C) for 20 min. thereafter, they transferred in a warm room (25°C) for 20 min.

2. 2. This pattern was repeated three times, total cold exposure time amounting to 60 min.

3. 3. In the warm room, the subjects removed their cold-protective jackets, or wore them continously.

4. 4. Rectal temperature, skin temperatures, manual performance and thermal comfort were measured during the experiment.

5. 5. Removing cold-protective jackets after severe cold exposure increased peripheral skin temperatures and reduced the discomfort in the warm room.

6. 6. However, these results were accompanied by a greater decrease in rectal temperature and manual performance.

7. 7. It is recommended that workers continue to wear cold-protective clothing in the warm areas outside of the cold storage to prevent decreases in deep body temperature and work efficiency caused by repated cold exposures.

Characteristics of the temperature regulation system in the human body

1. 1. To study a complex biological system such as human temperature regulation, it is necessary to consider both physiological experiments and theoretical analysis.

2. 2. This paper presents the characteristics of this temperature regulation system obtained from a mathematical model, together with experimental data and the influence of exercise and clothing.

3. 3. The experimental results showed a good agreement with the theoretical results.

Characteristics of wettedness under constant average skin temperature

1. 1. Experiments were carried out concerning the characteristics of wettedness revealed under constant average skin temperature using sitting-resting nude subjects. From the basic measurements of both environmental parameters and human physiological responses, the conclusions detailed below were proposed regarding the changes of wettedness under constant average skin temperature.

2. 2. There is positive correlation between the wettedness and environmental humidity, and negative correlation between the wettedness and air temperature.

3. 3. There is positive correlation between the evaporative heat loss from the skin surface and air temperature, and negative correlation between the evaporative heat loss and environmental humidity.

4. 4. There is negative correlation between the wettedness and evaporative heat loss.

5. 5. Wettedness is not constant but takes varying values, that is, corresponding to each average skin temperature both the maximum and the minimum wettedness values occur.

6. 6. Deriving from the items mentioned above, the theoretical locus of equal average skin temperature is not a straight line, but is a curved line plotted on the psychrometric chart.

An experimental study on the effect of humidity on thermal sensations of people in summer

1. 1. The authors propose humidity reduction instead of lowering room temperature in order to reduce cooling syndrome.

2. 2. They conducted experiments with subjects in the rooms, one with controlling humidity to about 40% r.h. and another without humidity control. Air-conditioning system with humidity control has a greater promise in making a comfortable environment, even at the temperature as high as 30°C, in comparison with conventional means using temperature control alone.

3. 3. Relationship of actual mean votes on temperature sensation and comfort sensation with PMV and SET, respectively, suggests that Japanese people might be more sensitive to humidity than Westerners and so different methods from those used in the western countries should be required for human thermal environmental studies with respect to the hot humid summer in Japan.

Skin temperatures, thermosensory and pleasantness estimates in case of heterogeneity in the thermal environment

1. 1. Seven thermal conditions were imposed on male sitting subjects (slightly clothed: 0.6 clo).

2. 2. A thermal mannikin was also used to determine the exact operative temperature, T₀.

3. 3. Conditions were: uniform (UN: all parameters at 24.5°C, air velocity at 0.15 ms⁻¹), heated ceiling (HC at 45°C), heated floor (HF at 34°C), cold floor (CF at 14°C), two conditions of one cold wall at 6°C (CW1 and CW2 respectively with and without air temperature compensation) and increased air velocity (AV at 0.4 ms⁻¹).

4. 4. Local skin temperatures and answers to questionnaires were obtained.

5. 5. Skin temperature variations were affected by conditions and slight T₀ changes.

6. 6. Comfort judgments were fairly well related to T₀, especially when expressed as differences between actual non-uniform environment and the uniform one.

7. 7. It is concluded that, in case of non-uniform environments close to thermoneutral zone, thermal comfort or discomfort reflects the climate alterations better than the thermal sensation does.

The effects of wind and thermal radiation on thermal responses during rest and exercise in a cold environment

1. 1. The purpose of this study was to investigate the effects of thermal radiation and wind on thermal responses at rest and during exercise in a cold environment.

2. 2. The experimental conditions were radiation and wind (R + W), no radiation and wind (W), radiation and no wind (R), no radiation and no wind (C).

3. 3. The air temperature was −5°C. Thermal radiation was 360 W/m². Air velocities were 0.76, 1.73 and 2.8 m/s. Rectal and skin temperatures, heart rate and oxygen consumption were recorded. Thermal and comfort sensations were questioned.

4. 4. There are no significant effects of thermal radiation and wind on the physiological responses except the mean skin temperature. There are significant effects on the mean skin temperature (P < 0.01) and thermal sensation (P < 0.05).

Physiological responses and thermal sensations of the elderly in cold and hot environments

1. 1. 10 elderly and 10 college-aged females served as subjects in cold and heat environments. The subjects changed into the standard clothing (0.63 clo), and stayed in the neutral environment (25°C) for 23 min, thereafter they were exposed to the cold (10°C) or hot (35°C) environment for 49 min.

2. 2. Then they returned to the neutral environment, and stayed there for 47 min. Oral temperature, skin temperatures at 10 sites, blood pressure and thermal sensation were measured during the experiments.

3. 3. In the cold environment, the elderly could not reduce heat loss by vasoconstriction as did young people, and their blood pressures increased more rapidly than in young people. In the hot environment, the elderly could not promote heat loss by vasodilation as did young people. Moreover, there is a delayed sensitivity to cold for the elderly. Therefore, in the houses of the elderly, it is important to have heating and cooling systems which also includes the areas where the people do not stay for a long period of time (e.g. toilet, passageways).

Thermal sensations during simultaneous warming and cooling at theh forearm: A human psychophysical study

1. 1.The forearm of 5 female subjects ws thermally stimulated by 2 sets of interposed servo-thermodes that respectively drove skin temperature at ±0.1°C.s⁻¹ for 25 s and then held it constant. Mean skin temperature remained constant. The sequence was repeated at adapting temperatures between 22.5 and 37.5°C.

2. 2.Thermal sensations, continuously reported by the position of a dial, were warmer for heterogeneous thermal stimuli than for homogeneous stimuli when mean skin temperature was greater than 30°C and cooler when less than 27.5°C.

3. 3.This phenomenon is inconsistent with a single additive contribution of “warm” and “cold” information to thermal sensations.

A new device for measurement of the thermal conductivity of fur and blubber

1. 1. A new and simple device for measurements of thermal conductivity of fur and blubber is described.

2. 2. The device measures temperature differences across the sample and across a polyethylene plate with known conductivity which is placed in series with the sample.

3. 3. The conductivity of the polyethylene was determined from the steady state temperature difference and heat flux through the wall of a polyethylene pipe with a central heat source.

4. 4. The accuracy of the device is ±4.0%.

5. 5. The thermal conductivity of harp seal (Phoca groenlandica) and minke whale (Balaenoptera acutorostrata) blubber, as determined by use of this device, is very close to previously reported values.

A study on body temperature regulation and residential thermal environments of the elderly—II. residential thermal environments at the kansai district

1. 1. An investigation was carried out on 3 male and 4 female elderly people, from 65 to 78 years ol.d The first survey was made in August and September of 1990 (in summer) and the second in January and February of 1991 (in winter).

2. 2. Matters for investigation were human subjects and thermal environmental elements of houses which were recorded by a portable thermo-recorder and a vinyl resin globe thermometer. Dry bulb temperatures at a height of 0.1 and 1.2 m and wet bulb and globe temperatures at 1.2 m high were recorded in the living room, bedroom, toilet etc., the thermo-recorders which measured air and wet bulb temperatures were kept out of the sun.

3. 3. Data was recorded constantly for 7 days at 20 min intervals. Plans of houses and furniture arrangement which influence the thermal conditions were drawn from video recordings. Physical and psychological surveys of individuals were carried out over 2 days of daily life.

4. 4. Subjects carried the thermo-recorders (YM1, YM2) on their side. Rectal, back of hand, sole of foot and ambient temperatures were measured every 2 min and with thermistor sensors. At the same time, behaviour and clothes, assessment of thermal sensation, comfort sensation and sensation of estimated room temperature were reported.

5. 5. Thermal radiation was measured with thermographs during the winter. Human activity was recorded every minute for 33 h. This report is the result of surveys in summer and winter.

6. 6. The following results were obtained: (i) the air conditioning is used sometimes in the houses of the elderly; (ii) thermal sensation range reported is narrow; (iii) skin surface temperatures of the elderly are relatively high and their range of change is narrow, and the range of rectal temperature in a day is narrow; (iv) high activity and excessive heating cause a rise of rectal temperature and the rectal temperatures are lower at rest time.