clothing comfort determining factors

7/30/2019 Clothing Comfort Determining Factors

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Clothing Comfort and its

Determinants

26/11/12Dr. Muhammad Mushtaq Mangatwww.mushtaqmangat.org

[1]


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Lecture 2Clothing Comfort Determining

Factors

Objective: To have an understanding about the factors

which have the ability to alter clothing

comfort


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Determining Factors

Comfort

Humanbody

Environmentclothing


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Interaction

Continuous interaction among human body,environment and clothing

Dynamic situation No stable situation Many more external factors


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Factors affecting clothingcomfort

Factors related to the wearer (metabolism of person, age, experiences, level of

health, mental and economic position, types ofactivities)

Clothing structure and chemical nature of fibers (fibre and yarn types, fabric structure,

mechanical and thermal properties of fabric,clothing design, fitting)

External Conditions (moisture, ambient and radiant temperature,wind speed)


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Human body

A complex system Needs intake to produce heat Heat is used as energy to keep running the

whole system

Food energy is converted into thermalenergy

Activities increases energy by using storedfat energy


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Human body: a fuel cell

Consumption of food is similar to combustion but notexactly

Combustion produces heat as by product ofcombustion

Human body needs a constant temperature forsmooth running

Higher temperature increases the reaction rate andcauses discomfort

Shivering increases the heat production process byutilizing stored energy (fats)

Not heat, no required temperature result is death


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Conti

Source of heat is burning of glucose Human body breaks the glucose and gets

energy

Produced energy is always higher thanrequired

Excess energy needs to be removed


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Heat Production Due To Exercises


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Dog has fewer sweat glands, keepmouth open to release extra heat


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Human Body Physiology


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Human Body and ThermalTransfer

Humans are bipedal while animals are quadruped. Human has 40% less expose to radiation as compared to animals Human head is at height and experiences cool and wind blowing more than other

parts of body.

Human skin has four layers and the inner parts are bones, muscle, fat and finally skin. More than 80% heat is produced in muscle Occurrence of heat production and its consumption is concurrence process Always difference in heat production and consumption Heat production and consumption is regulated by the brain. Skin quality, thermal receptors, radiation, evaporation, sweat glands, shivering

process, metabolism rate, and experience affect this regulation.


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Amount of Heat

Human body produces heat depends uponthe intake at rest position

Average human takes 2400 Kilocalories, It is equal to 2791.2 Watt or 116.3 Watts per

Hr

Commonly 100 Watts is taken in general Human body area is between 1.6-1.8 m2 116/1.6= 72 W/hr or 116/1.8= 64 W/hr


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[11]


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Environment and Human

Body [2]

Human bodyexchange heat with

environment through

conduction,radiation,

convection

Sweat generationand evaporation isalso a method to

dissipate heat

http://hyperphysics.phy-

astr.gsu.edu/hbase/thermo/imgheat/bodycool4.gif


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Human Body Temperature Control Neural feedback mechanisms controls the temperature of

human body through the hypothalmus

It is based on sensors attached with hypothalmus Sweating and shivering are two main action which body takes

after sensing the variation of temperature

Vasoconstriction to decrease the flow of blood in case of winter Vasodilation to increase the blood flow in case of high

temperature

Sweating to decrease the skin temperature and shivering toincrease the skin temperature

Erection of hairs on skin increase the thermal resistance undercold conditions [3]


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Human body temperaturecontroller [4]


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[5]


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Human Body Heat Exchange [2]


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Cooling of Body [2]


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Heat Transfer and Human body [6]


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Shade for Cooling


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Human temperature Variation[7]

Chart showing diurnal variation in bodytemperature, ranging from about 37.5 C from 10

a.m. to 6 p.m., and falling to about 36.3 C from 2a.m. to 6 a.m.


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H&M transfer and Clothing [8]


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Moisture Flow through Clothing [9]


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Schematic diagram of liquid water and moisturetransfer of clothing system [10]


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Primary Function of Clothing

Thermal insulation Support to transfer moisture from skin to

environment

Protection from radiation Social satisfaction Safety of human body from injuries Facilitate for better functioning


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Clothing and Thermal Insulation

Clothing provides thermal resistance Thermal resistance is measured in clo Clo= 0.155 m2K/W It is zero for a naked person and 1 for an

ordinary suit

It depends upon the moisture, structure andfiber contents of clothing


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[11]


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[12]


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Environment

Environment is third factor in clothingcomfort

Three main elements of environment: Temperature (ambient, globe) Humidity Wind speed


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Environment Temperature

Heat flow due to temperature differencethrough conduction. Human body remains in

touch with adjacent things directly or

through clothing

Air wind affects the heat transfer throughconvection process

There is a net difference of heat transferthrough radiation


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Humidity Ratio

Humidity affects the moisture transfer from skin toenvironment

Higher humidity will reduce the difference inhumidity level between skin and air

Skin becomes unable to transfer heat throughevaporation and human body temperatureincreases

Clothing also reduces the moisture flow

Clothing having ability to transport moisture from skinto environment are much liked


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Summary

Thermal comfort is highly dependent upon theheat produced and heat dissipate from humanbody

A balance is required for a better thermalcomfort

Balance is achieved by increasing heatproduction (activities and food, increasingambient temperature, heavy clothing to provide

insulation), or heat loss (decreasing ambienttemperature, high wind to take moisture,minimum clothing)


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Activities

Calculate total clo of your clothing andcompare with others

Measured clo values of your clothing underdifferent temperature

Is there any linear relationship between thesetwo


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References

[1]Robert E. Peary in the clothes he wore when he explored the North Pole, Source:http://www.bing.com/images/search?q=clothing+of+north+pole+&view=detail&id=1E6D08E67DD13306D836128EE217E4094FCC9E75&first=61&FORM=IDFRIR [2] http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/imgheat/bodycool4.gif[3] http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatreg.html

[4] http://en.wikipedia.org/wiki/File:Illu_diencephalon_.jpg[5] Gersak, J., & Marcic, M., Development of a mathematical model for the heat transfer of the systemman clothing environment. International Journal of Clothing Science and Technology, 2007. 19: p.234-241.[6] Bartiz, M., et al., Human Body Tempertaure to Analyze the Comfort during Manufacturing Process, inInternational Conference 6th Workshop on European Scientific and Industrial Collaboration on promoting

Advanced Technologies in Manufacturing WESIC082008: Romania.[7] http://en.wikipedia.org/wiki/Thermoregulation[8]http://www.bing.com/images/search?q=heat+and+mass+transfer+through+clothing&view=detail&id=C36BC550AAF5B04C53030467CB0F6E90063CF386&first=31&FORM=IDFRIR

[9]Gersak, J., & Marcic, M., Development of a mathematical model for the heat transfer of the systemman clothing environment. International Journal of Clothing Science and Technology, 2007. 19: p.

234-241.[10] Satsumoto, Y., Murayama, C., and Takeuchi, M. , Effect of Moisture Sorption of Underwear Material onClothing Microclimate in a Hot Environment. Heat Transfer-Asian Research, 2009. 38(1).

[11]Source: http://www.engineeringtoolbox.com/clo-clothing-thermal-insulation-d_732.html[12] Source: INNOVA Air Tech

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