Clothing Comfort

A Combination of Objective and

Subjective Evaluation

Presented to:

Prof. Dr. Lubos Hes

By:

Muhammad Mushtaq Ahmed Mangat

Technical University Liberec

April 12, 2010

1

Clothing Comfort: A Combination of Objective and Subjective Evaluations

Introduction

Clothing is one of the fundamental needs of the human being. It serves various and diverse

purposes. Clothing selection is based on the needs and desires of the people. It may be to satisfy

some aesthetic needs or to fulfill any particular demand of human being. People’s selection of

clothing depends upon their perception and feeling about the clothing. In some cases it is

recommended to wear certain clothing and selection is not possible, for example dress of a

firefighter, military uniform, etc. However, it is very common that there is a dynamic and

fundamental changes in the preferences of people with the change in the context; season, climate,

age, type of activity, etc. It is highly linked with the core requirement why a person is wearing any

particular clothing. Moreover, clothing requirements are rather different depending upon the type of

activities of any person. However, comfort is a basic and introductory prerequisite of the people in

all situations and is considered a threshold in selecting the clothing.

Comfort is difficult to explain since it is a complex and interdependent combination of physical,

psychological and sensorial perceptions and highly depends of subjective evaluation of the

individuals. It is not possible that comfort level of every one sitting in an office could be same, even

temperature, air velocity and other parameters, which they are experience are same and comparable,

even then comfort sensation is quite diverse. However if more than 80% people feel comfort, then it

can be said that such environment provides a comfort (ISO). Same is the case with clothing

comfort.

Literature provides a number of mathematical models to predict comfort but still final decision is

made based on subjective findings by using clothing in real world. There is a continuos research to

produce clothing which should be able to provide higher level of comfort. It is not possible to make

clothing suitable for every situation. Industry is producing different designs, colors, patterns to

provided better look for wearers and at the same time functional clothing to fulfill certain demands.

For example, water proof jackets, fire fighting suits, etc.

This work is an effort to describe different faces and facts of clothing comfort. The core objective is

to provide a summary of clothing comfort, which is science as well as an art. It is evident from

fierce competition in clothing market, that expectations of consumers have increased many folds

2

and in diverse directions. Clothing comfort parameters, all three; physiological, psychological and

sensorial are now market tools. More over people are also considering the ecology. They prefer

supplier which provides information about their contribution to in making this planet a better place

to live. Beside that current time is an era of competition based on performance. Protected and

restricted access of suppliers is a diminishing idea. Import transaction barrier are being removed,

additionally IT has provided maximum information under finger tip and in most of the areas of the

world. Clothing suppliers are having a strong contact with their costumers and end users.

Companies to have pay attention to the voice of customers and they live on their feed back rather

than relying on government policies to provide any protection from competitors.

Emergence and Development of Clothing Comfort Science

Hollies et al. (1979) has discussed the emergence of clothing comfort science and quoted various

examples which indicate how people have turned their faces towards clothing comfort. Extension of

thermal adaption approach by ASHARE, work of Rees to add surface characteristics, research

carried out by Hock et al., Bogaty & Mehrtens are few examples, which provide enough

information to workout that 1940-1950 period can be considered as birth period of clothing comfort

science. During this time, clothing comfort was taken as a separate discipline labs were set, courses

were taught, books were written and many thing more, however it is hard to fix the exact time. Still,

debate is continue about the birth of clothing comfort science. It is evident from the survey of

literature, which provide a serious discussion difference between heat-balance approach and heat

adaptive approach. People have different point of view about the initiating point.

Temperature and humidity are the main contributor in the overall comfort. This dependency

becomes more significant when we are the ends of the scale. As a matter of fact, some people have

more ability to adapt the changed environment. People response with different magnitude on any

change in temperature or humidity, which are fundamentals of comfort. Harmony among all factors

concerning with the human being is fundamental requirement for comfort. It may be physical,

psychological, sensorial, environmental, economic and many more. Literature provides evidence

that there are three broad categories of comfort; psychological, sensorial and physiological. It is

more complex and tiresome to conclude which one is preferred by people. Nonetheless, it is true

that context plays an important role in preferences. For a military commander, while taking salute, it

is most important that how clothing looks. He wants to deliver a non verbal message that he owns

authority. At this stage psychological comfort is much significant and physiological comfort has

3

second position. By and large people can live under wide range of temperature and humidity, which

are major contributor in thermophysiological comfort. Contrary to this there are people who reach

in discomfort situation even there is a slight unwanted change in environment.

Literature provides a number of studies conducted in lats couple of years to note down the

preferences of the customers. Kaplani and Okur (2008) have quoted some of them, like, study of

Fujiwara et al. (1994) to assess consumer perception of apparel quality, work of Heller and Schiff

(1991) to determine comfort, fit, style, color and quality. Survey of Silverman (1999) and Wong and

Li (2002) about the stated comfort, garment fit, easy care and durability. Results of the effort of Wu

and Delong (2006), which was focused to find out the significance of design, fashion, comfort, fit

and guaranteed quality, survey of Zhang et al. (2002) which concluded that fit, comfort, style, color

and workmanship as the most important casual wear attributes, Richards and Horridge (1984)

survey of a group of American home economists, study about consumer clothing quality evaluation

by Swinker and Hines (2006), investigation through two survey studies by Hong and Guolian

(2004). It is not an exhaustive list. There are many more studies reported in literature and it is

presumed that in future reliance of clothing manufactures will increase on customer feed back and

survival will depend upon the best match between preferences of the customers and technical

parameters of the clothing.

Among all mentioned surveys, work of Kaplani and Okur (2008) is most latest one. It is imperative

to quote here their findings so that one may get an idea what people are looking for. They have

summarized their findings in the following table. This table tells that nearly one-third focus of

customers is on cool and warn feeling and lowest consideration is given to laundry instructions.

It is obvious from the table that most of factors are related to heat and moisture balance. This is the

area which will define the role of objective and subjective evaluation standards and will play most

significant role in the marketing and companies will be judged based on their performance in this

area.

4

Table 01

All above discussion is an effort to describe the significance of clothing comfort which has been a

point for discussion in last few decades. It is also important to note that US has played a major role

in this area and they developed most functional clothing for military personnels. Despite that, it is

not possible to define exact time when clothing comfort science became part of syllabus.

Clothing Comfort: A Descrete and Ubiquitous Concept

We start our discussion keeping in mind that comfort is a property or characteristic of clothing

which is not so easy to quantify due to various complexities attached with it. For example, thermal

comfort a major part of clothing comfort and is ruled by the heat transfer laws. In case of thermal

clothing comfort it cannot be judged purely based on heat transfer equations. Because the presence

of human being on one end is not so simple as heat transfer phenomenon. Human being has its own

dynamics, which are quite diverse and cannot act in a uniform way. People will react in a different

way and intensity of reaction will also be different. This is the main reason that we consider

clothing comfort is a subjective feeling and it is quite difficult to define all factors and their

contribution level which can affect this feeling. Nevertheless, up to certain extend we can predict

the response of human being by conducting different tests, particularly, related to heat and moisture

transfer, surface friction, bending rigidity, etc.

Thereby we can divide factors which can influence comfort into three main categories:

1. Factors related to wearer (metabolism of person, age, experiences, level of health, mental and

ecomoc position, types of activities)

2. Clothing structure and chemical nature of fibers (fiber and yarn types, fabric structure,

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

5

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

Clothing Comfort concept is much easy to understad from the following statement, which is quite

comprehensive:

It [comfort] depends on many factors such as the temperature of the environment, the relative

humidity, the wind velocity, the metabolism of the wearer and, of course, the characteristics of the

clothing materials, e.g. materials’ thermal comfort properties, which display their abilities to

transport heat and moisture from the human body’s surface into the environment. The measuring

values that reflect this ability are clothing’s thermal resistance or thermal insulation, and water

vapour resistance. Many other factors such as colour, fashion, a person’s physical and psychological

state also influence the feeling of comfort (Mecheels, 1998 as cited by Celcar; Meinander and

Gersˇ, 2008).

It can be conclude that one of the major findings relating human comfort to the atmospheric

environment is the recognition that comfort depends upon more than one atmospheric variable.

Thus, the sensation of heat or cold depends upon variables other than measured atmospheric

temperature. This observation has resulted in the development of biometeorological indices that

attempt to predict the various human responses to the sensations of warmth and cold and to further

assess the physiological strain imposed by the combined atmospheric variables ( Yan and John,

1995)

There are a number of definitions of clothing comfort coined by researchers and scholars. Here we

are giving few definitions to understand the idea of clothing comfort. “Comfort is defined as the

absence of perceived pain- and discomfort as taught by Prof. Lubos Hes. Mine et al. (2009) explain

“Clothing comfort is a state of satisfaction indicating physiological, psychological and physical

balance among the person”. Above both definitions are quite interrelated and intriguing the same

idea but with a subtle difference. Clothing Comfort perception put forward by Celcar; Meinander

and Gers (2008) gives more elaborated view, it states “Clothing wear comfort is a state of mind

influenced by a range of factors and is the result of a balanced process of heat exchange between

the human body, the clothing system and the environment.” ASHRAE defines thermal comfort as

an expression of mind that expresses satisfaction with the environment.

6

Above mentioned four definitions are well defined and have certain framework, which is mainly

consist of thermal and moisture balance. There is a lack in above definitions that having a required

and acceptable level of thermal and moisture balance between human body and the environment

does not provide the manifest to define clothing comfort in a comprehensive way. There are many

factors which are missing in these definitions. The most important is psychological and sensorial

comfort, influence of emotional and economical level, variation due to previous experiences, etc.

Diagram 01, well explains the response of different factors which contribute in overall comfort.

Diagram 01: Human Signal System

Source: http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio

%20102%20lectures/sensory%20systems/sensory.htm

7

Y. (2001) proposes the following model which explains the clothing comfort process.

Figure 02: Clothing Comfort Sensation Process (Y. (2001)

In nut shell, comfort is an out come of a network of different physiological, psychological and

sensorial feelings, which are based on the information provided by different parts of body, like,

eyes, nose, hands, tactile senors, heat observers, brain. In addition it is the state when human is at its

lowest stimulation. It can be said it is a state when brain feels a minimum stress and strain. This

level is different for different persons and even for a same person varies a lot with the variation in

the context. For example, a bed sheet is much comfortable when ambient temperature is between

20-25 Centigrade and it will give uncomfort if the ambient temperature is much low or high.

Human body reacts when there is a change in the environment. Intensity of reaction is well defined

mathematically. Diagram 03 is a pictorial explanation to understand the reaction of human body on

change in its temperature.

8

Figure 03 Reaction of Human Body on Temperature Variation

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

Building Blocks of Clothing Comfort

Relying on information available in literature, it can be deduced that clothing comfort is considered

as function of aesthetic, sensorial and thermophysiological comfort. Raj and Sreenivasan (2009)

along with many scholars are of the same view. They also classify the clothing comfort into three

main categories; aesthetic, thermophysiological, and tactile. All three categories have quite diverse

in nature and serve different purposes and perform different functions.

The most significant factor is thermophysiological comfort and it defined as the process which

explains the changes occur in human body due to change in temperature. It is a known fact that

human body is a thermal engine and produces heat and it has a strong link with environment

temperature. Furthermore, there is a constant change in the environment, thereby, body has to react

accordingly and take necessary actions to keep itself intact from the vraition of ambient

temperature. Human body takes different steps to have a balance with external environment.

During this process there will be heat transfer phenomenon. In cold weather, body will lose its heat

and to stop it we use clotheing and in hot summer, we wear light weight and porous clothes so that

our body heat may be reduce and it hleps in heat loss through convection, radiation, conduction and

9

evaopoartion. All such efforts are focused to satisfy soft needs of wearer and to develop a thermal

balance.

Aesthetic comfort is highly dependent on designing, coloring, sewing, packing, embellishment, etc.

It needs a separate discussion. In this report our main purpose is to discuss the two building blocks;

thermophysiological and tactile (sensorial) comfort. However, we will provide a brief of

psychological comfort.

Psychological Comfort

Although discussion about the psychological comfort is out of the scope for this work, it is found

imperative to list down the factors which has a significant correlation with the psychological

comfort. Prof. Lubos Hes provides the following list of factors which have a great affect

psychological comfort:

4. Economical aspects: Resources, technology of food and objects manufacture, skills, political

system,

5. Historical aspects: Inclination to products made of natural materials, to products simulating

nature, to products of natural smell. Tradition in lifestyle and fashion.

6. Cultural aspects: religion, habits (in Arabic countries women are fully covered)

7. Social aspects: age, qualification, social class, rank or position in this class

8. Individual and group aspects: the effect of fashion, style, colors and luster, trends, personal

preferences

It is presumed that intensity of factors varies a lot depending upon the context, which people are

experiencing. There may be many more factors which are missing from the list and has become

significant with the passage of time.

Sensorial Comfort: Easy to Estimate

Sensorial comfort is relatively a young subject which has attracted much attention of people.

Currently it is the topic which is highly focused (Y. 2001). Most of the clothing as a whole or partly

touches the human skin. Under garment are fully in touch with human body, however jackets, coats

or sweater may have partially contact with human body. Beside that, their hand feel is also

important since our hands are regularly in touche with the clothing. Sensorial comfort depends upon

10

mechanical and chemical properties of fabric. It is not possible to discuss sensorial comfort without

discussing the thermal comfort. Anyhow, we have tries to discuss both topics separately.

Figure 04: Skin Details

Source: http://i.imgur.com/wGB4Jl.jpg

Importance of sensorial comfort can be judged by the work J.Y. Hu Lubos Hes Y. Li, K.W. Yeung

and B.G. Yao. They successfully developed, Fabric Touch Tester (FTT), which is used to integrate

evaluation of thermal–mechanical sensory properties of polymeric materials. Inventors of FTT are

fully convinced that clothing which is directly in touch with the skin have effect on overall comfort.

FTT measures, records and analyses thermal and mechanical sensory stimulations and propagations

occurred while clothing becomes in touch with the human skin. FTT can be used to predict many

mechanical properties of clothing, like smoothness, softness, prickliness, warmth and dampness.

Instead of the highest precision level of FTT, even then there is a need of subjective evaluation of

the clothing.

11

People generally estimate clothing comfort level just by touching with hands and have to rely on

their touch sense and they take decision based on their very raw observation. Generally following

factors of clothing can be judged by human fingers:

1. Softness

2. Smoothness

3. Bending rigidity

4. Elasticity

5. Warm and cool feeling,

6. Thickness of the fabric

7. Shear rigidity

8. Hand fullness

9. Wrinkle behavior

In current era there is a rising trend to do shopping online, and it is becoming difficult to touch the

clothing before buying. For this reason there is a dire need to have some mechanical evaluations,

enough to predict different characteristics of the fabric. For such information there is a need to have

a uniform and acceptable method. There is a successful effort by different institute. One of the most

significant example is of Hohenstein Institute in Bönnigheim, which was established 1946 and has

gained international reputation. This institute provides labels, which are attached with the clothing.

Figure 05: Clothing Comfort Labels

12

Another example is of Kawabata system which is also used to have better idea about the comfort.

There are five Kawabata Evaluation System (KES) instruments. These instruments measure 4

modulus and 16 parameters, like, fabric bending, shearing, tensile and compressibility along with

surface smoothness and friction and many more.

Figure 06: Friction Measuring Instrument by KES Japan

Other than above instruments, Dr. Lubos developed ALAMBETA and PRMATEST to measure

thermal properties and moisture permeability of fabrics. These testing machine can measure heat

and moisture behavior of different fabrics. Results can be used to predict the clothing comfort level.

There are many universities and manufacturing firms using these two equipments. List of

instruments and laboratories is not short. All efforts is an evidence that there is an increasing trend

to have mechanical evaluation of fabric before sending it to market. These evaluations serves many

purposes. The foremost is a base to develop new products. Today it is used to market the products,

particularly; it is much useful in case of online clothing marketing. Prof. Lubos explains the

German method of objective evaluation of complex sensorial comfort of worn garments, which is

based on large experimental investigation. They have developed following equation based on a

large experiments:

Where:

Imt = index of water vapor transmissionIk = index of water vapor transmissionIB = index of wetting Io = Surface indexnk = Number of contact pointsS= Bending rigidity

13

Numerical values of constants:

!1 = -2,537 !5 = 1,71.10-3

!2 = 1,88.10-2 !6 = 3,86.10-2

!3 = 2,29.10-3 " = 0,36

!4 = 2,09.10-2

As per calculation total sensation 1 is equal to .35 sensorial and .65 thermophysiological comfort.

Equation for Thermophysiological Comfort

Where:

imt= Water vapor transmission

Fmt= Dynamic water vapor absorption Kd= Liquid moisture buffering coefficient Bt= Temperature buffering coefficient Kf= Moisture permeability

Numerical values of constants:!

1 = -5,640 !

4 = -4,512

!2 = -0,375

!

5 = -4,532

!3 = -1,587 " =11,553

Total comfort: TK

tot = 0,35 . TK

H + 0,65 . TK

T

Lubos further explains that sensorial effect is a combination of of mechanical, thermal, acoustic and

visual perceptions of comfort. The index range is 1-6, where 1 means the best and 6 the worst.

Y. (2001) has listed 26 sensory desciptions after a thorough survey. Some pof them are listed here:

1.Snug

14

2.Loose

3.Stiff

4.Light weight

5.Staticky

6.Non-absorbent

7.Sticky

8.Heavy

9.Cold

10.Damp

11.Clammy

12.Clingy

13.Picky

14.Rough

15.Scartchy

16.Hot

17.Soft

18.Warm

19.Prickly

20.Itchy

21.Chill

22.Sultry

23.Tickling

24.Raggy

25.….

26.….

Skin Sensibility and Its Measurement

Skin is highly sensitive to pressure and change in temperature along with humidity level on its

surface. Clothing is an extension of the human body its first layer has a direct touch with the skin.

At the same time micro climate is produced, where on one side there is a skin and on other hand

there is a clothing layers. Micro climate is quite dynamic in nature as compare to the macro climate.

Any change in micro climate is sensitized by the skin and skin sends signal to brain which develop

15

a local and overall comfort due to clothing. There are many test available to test the changes in skin

due to changes in micro climatic conditions. For example, Hohenstein Institute has developed

many tests to evaluate cling index, number of contact points and surface index, stiffness and

sorption index. A group Yehia El Mogahzy, leader; Faissal Abdel-Hady, Roy Broughton, Gisela

Buschle-Diller, Ramsis Farag, Asaad Mohamed, David Pasco, B. Lewis Slaten (Auburn),

Bhupender S. Gupta (NC State) Radhakrishnaiah Parachuru (Georgia Tech) are developing a

Design-Oriented Fabric Comfort Model. The blueprint of the model shows (Figure 07) that they

have taken both micro and macro climate into account. Their aim is to develop "virtual intimacy

measurement of fabric comfort using structural, fuzzy-logic and psychological modeling to replace

the traditional intimacy of touch.”

Figure 07: Design-Oriented Comfort Evaluation Model by Yehia El Mogahzy and Associates

Sensorial sensation can be divided into two main categories; neurophysiological and

thermophysiological comfort. Neurophysiological parameters are mainly concerned with the

sensation (stimulation) occurred when our skin, which is composed of number of nerves becomes in

contact with the surface of fabric. Skin, which is highly sensitive can observe the level of surface

smoothness, crispness, roughness, stiffness. Even our skin can make observation regarding warm

and cool effect of the fabric. Whereas, thermophysiological comfort parameters are mainly related

with the heat and mass transfer phenomenon, which covers, change in skin temperature, level of

moisture at the skin surface and pressure of air flow.

16

After carrying many tests, Hohenstein Institute has put forward results which reveals that

thermophysiological characteristics account for about 66% and skin sensibility contributes nearly

one-third in the overall perception of clothing comfort.

Steven (1906-1973) proposed a power law. This law governs the relationship between magnitude of

the stimulus and its impact perceived:

Where:

I = Magnitude of the physical stimulus

!(I) = Magnitude of the sensation

a = Exponent depending upon the type of stimulation

k = Proportionally constant related to the type of stimulation and the units used.

Where:

I = Magnitude of the physical stimulus

!(I) = Magnitude of the sensation

a = Exponent depending upon the type of stimulation

k = Proportionally constant related to the type of stimulation and the units used.

17

Table 02: Sensation Index

(http://en.wikipedia.org/wiki/Stevens'_power_law)

18

Deformation Angle

Fabric rigidity plays an important role in its overall comfort. Human body is not straight. It has lot

of bends, furthermore, during performing different tasks, different parts of body have to move.

This movement is mainly consist of bending. Bending of fabric depends upon its thickness and

length.

y = F l3 cos2" sin" / 3 E I

Where:

Y= Deformation

F= Force

I= Inertia moment

Where Inertia moment is:

I = # d4 / 64

Above equation depicts that fiber deformation is directly proportional to third power of its length

and indirectly to fourth power of its diameter. Due to this fact micro fibers bend easily and provide

large area of contact between skin and fabric surface. Thereby, heat transfer area increase and we

feel fabric surface cool. Overall fabric made by microfibers provides cool feeling.

Bending righty also depends upon their packing coefficient. Prof. Nescar has developed this

model. Following equation explains the relationship:

B = E . I Where:I = b.h3/12

Drape Angle and Its Theory

Drape angle is another parameter of fabric in clothing comfort. Niwa and Seto have developed

following equation to estimate the drape behavior of the fabric. regression equation given below,

DA = DA=C

0 + C

1 (B/W)0,33 + C

2 (G/W) 0,33

19

There are many ways to measure it. Here we explain a very simple method as taught by Dr. Lubos.

Figure 08: Drape Angle Measuring Method

All above discussion provides compelling evidence that sensorial comfort is a one of the major

areas of concern in overall clothing comfort. It is quite complex and improper evaluation can lead to

some wrong decision. For example, as described by Hipler and Elsner (2006) “The skin sensorial

comfort is negatively affected by hydrophobic, smooth [flat] surfaces that easily cling to sweat-

wetted skin, or which tend to make textiles stiffer. As guidelines for the improvement of the

thermophysiological or skin sensorial wear comfort, it is recommended to use hydrophilic

treatments in a suitable concentration and spun yarns instead of filaments.”

Thermophysiological Comfort

Thermophysiological comfort is a fundamentally important element of outdoor garments since they

are intended to be worn in various weather conditions, often while the wearer engages in strenuous

activities; the anticipated environmental conditions and the clothing system are accepted to be the

other key elements to consider during design and manufacture. Ruckman et al (1998)

20

Papkov (1981) views the thermal imbalance as the core reason of discomfort. Papkov prefers to

discuss discomfort instead of comfort. Since explanation of discomfort can easily be discussed and

simple to understand. It may be due the fact the human being sense is more prone to discomfort as

compare to comfort. They easily and quickly identify the discomfort as compare to comfort human

body is a thermal engine, which produces heat to run its different functions of the body. Our food is

main source of energy. Nevertheless there are many other ways to produce heat, like, running can

increase the body metabolism, which increaes the enternal and skin temperature. There is a direct

and indirect interaction of skin and environemnt, both surfacrs have different temperatur. This

temperature gradinet provides the basis of heat transfer. Common heat transfer laws govern the heat

flow from body to environment or vise versa. If there is a heat flow from body to environment due

to cold weather or from environmnet to body in a hot atmosphere. In both cases there is a chance

that temperature of human skin will fall over and under the temperature which creates discomfort

for the human body.

Barker (2002) points out two main distinct features of thermophysiological comfort. One is normal

wearing and the other is transient wearing conditions. In both cases there is a need of

thermophysiological comfort which mainly depends upon the thermal balance between body and

the environment. Clothing is an extended part of body and sometimes it is stick to the body. For

example, ski player wear suits which are quite stick to body. Whereas, people prefer to wear suits

which are loose fitted so there is a gap between the body and the clothing. In both cases thermal

regulation will be different and role of clothing thermal properties cannot be ignored.

To avoid any uncomfort there is a need to create an equlibrium between the internal and external

temperature. For example, in cold weather, there are two ways to keep the balance; either more heat

production (by doing exercise) to keep body warm or covering the body with such materials which

could stop heat flow through radiation and conduction. Same is the case in hot environment. In this

case, one has to keep body covered from heat or exposouser of body to atmosphere so that there is a

sweat evapration, which ultimately reduces the body temperature.

In both cases there is need of such clothing which could provide comfort to human body. The

propoerties of clothing which deals with comfort are quite complex and there are numerous factors,

which can affect clothing comfort. Some scholars have discussed this phenomenon under the

21

heading of thermal comfort. Satsumoto et al (2009) investigated the comfort of underwear by using

different materails and their combination and concluded that mositure absorbency has a significant

role in provision of comfort. Thermal comfort depends upon the imbalance in the heat. For better

control of temperature to keep it at low level it is necessary that there should be a evaporation of

sweat. Evaporation is a endothermic process and keeps temp low which provides a comfort to body.

The premsie of this whole phenomenon is based on the mositure absorbency and evaporation

capabilities of the fibers. This study reinforced the idea that thermal comfort of human body is

based on the heat tranfer but it is quite complex as compared to the process where there is no

moisture.

Heat and Moisture Transfer from Skin

Human body tends to be at steady state with environment by keeping a thermal balance. Extra heat

produced by metabolic process or due to any activity is transferred to environment primarily

through convection, radiation and small portion through conduction. If these mediums become

insufficient then evaporation is the last method. Working of thermal engine of human body depends

upon many factors, which are mainly related to the physiology of human body and its working

conditions. Intensity of thermal generation will be different for a child and an old man.

Furthermore, human body will produce less quantity of heat while it is in rest position as compared

to when a person is running. Additionally, there are many more factors, like, type and quantity of

food, health conditions, age, etc.

In heat transfer phenomena two terms are most common; heat and temperature. These two terms are

quite distinct in nature but sometimes used as synonymous of each other. Temperature is a relative

term to feel cold or hot. It is average KE possessed by the substance. Whereas, heat is an energy in

transit, ready to transfer from hot body to a cool body. Temperature gradient is the main driving

force in heat transfer. For temperature we use thermometer and measure in Celsius and Kelvin

scales. Contrary to this heat is measured in Joule and Calorie and symbol is Q. Heat transfer process

is denoted by q. We can concluded that heat is an energy in transit ready to move from one

substance to other. Its direction is determined by the temperature difference. It always move from

hot to cool place. For this reason a negative sign is put in heat transfer equation.

22

Heat production is a regular function of the human body. It is much required to keep the whole body

in function. Production of heat depends upon many factors, like level of activities, age, food taken,

etc. There is need to dissipate the extra heat produced by the body. If this extra heat is not removed

from the body, it will create uncomfort for the human. There are two main ways to dissipate this

extra heat; through skin and through respiration system. In respiration we take moisture and heat

from lungs. The discussion about this process is out of the scope of this article. The second method

in which heat transfer takes place through skin is the area where we need to discuss in detail.

Figure 09: Body Temperature

Source: Barite (2008)

Our body has its own thermal regulation system. 1Keith C. Heidorn, PhD provides a in-depth

information about it. This report reveals that there are two sets of heat sensors present in the human

body. First indicates the outflow of heat from human body. It lies close to the surface of skin and it

is concentrated in the finger tips, nose and bends of elbow. The second works in case when body

temperature is low as compare to environment and body gains heat. It is present deeper in the skin

and is concentrated in the chest, upper lip, chin, nose and forehead. The core function of both

sensors is to send signals to brain, which take action to counter the affect of heat transfer from body

to environment or vise versa.

Thermal regulator of human body is called hypothalamus. It is a gland which is present at the base

of brain, just above the pituitary. It is set very close to 98.60 F (370 C) and keeps monitoring of the

body temperature through blood temperature. Blood circulation is the main source of thermal

distribution throughout the body. After sensing any change in blood temperature, hypothalamus

23

1 http://www.islandnet.com/~see/living/winter/personalcomfort.htm

reacts accordingly and initiate physiological response to increase or decrease the temperature of the

body. This all efforts is to have body temperature very close to the set temperature 98.60 F (370 C),

at this temperature human body has the best comfort level. Any drastic change in blood

temperature, low or high will cause uncomfort.

Heat Transfer Through Evaporation

There is a strong need to understand the whole mechanism of heat transfer in the presence of

moisture. Ruckman et al (1998) describe that “ Theories and mechanisms have been established on

the basis of Fick’s Law and it is now widely believed that both heat transfer and moisture transfer”.

We can estimate the amount of heat produced by human body. Literature provides a number of way

to estimate the heat produced by the human body. Papkov (1981) has discussed it in length, we have

derived following information from Papkov (1981).

Human body needs different amount of energy to maintain its activities. It ranges from 7,560 J/day

to more than 21,000 J/day. It is equal to 420 J/h per meter square of the human body. This variation

depends upon the working of the human body. It is very simple to understand that if one person is in

a rest position it just needs heat to maintain the functions of the body, like respiration, etc., but in

case when a person is running and doing sever exercise it will burn more calories and will need

more calories to maintain the working of human body. However, on average person needs 840-1260

J/m2//h.

There are two ways to remove heat from the body. One is heat transfer through convection,

radiation and two is energy consumed in making evaporation of sweat evaporation (mass transfer).

In this case sensible heat is used in latent heat. Both processes are happening at the same time and

this continue till there is a temperature gradient becomes zero or negligible or not enough to work

as main source of heat and mass transfer.

In case when human body is directly in touch with environment, main heat transfer takes place

through convection and radiation. Heat transfer through conduction is quite less since direct contact

of human body with any other substance is quite low. It may be through feet if these are directly in

touch with the floor.

24

When human body is covered by clothing, which is most of the cases happens. Notwithstanding,

there are certain parts of the body which are not less often covered but generally major part of the

human body is covered for most of the time. Body is producing heating and transferring it to

environment. If this transfer is stopped by the clothing shield, humidity will tend to increase and

discomfort is the ultimate result. Since most of our fabrics have fine capillaries to transfer this

moisture from skin to environment and this evaporation process continues. This evaporation follows

all laws related to heat and mass transfer.

There is a need of 2,436 J to evaporate 1 gm of water. This heat is drawn from the skin to evaporate

water from the skin surface. According to calculation there is a need to remove 0.0021 J/m per

square centimeter of the body. It is about 10-6 g of water per cm 2.min. It is a known fact that

evaporation is directly proportional to the difference in partial vapor pressure between two systems.

As it is obvious from the whole process that there is accumulation of moisture on the skin due to

clothing shield and ultimately there will be less difference of moisture percentage on skin and in

environment. Result is low evaporation. In this situation, there are two possibilities; first use of

human body to work as latent heat and the second is movement of air to supplement the evaporation

process. In clothing comfort removal of moisture is extremely important since more moisture will

create uncomfort in shape of heat, sticking, cling, irritation, etc.

In real world there is a diverse situation about the RH and air velocity. However, for calculation

purpose 4-7 m/minute is taken as standard. Under the standard humidity around the surroundings

and standard air velocity the rate of evaporation from a surface is in the range of 10-3--10-4 g of

water per cm 2.min. By comparing the required amount of heat to be removed from body, which is

10-6 g of water per cm 2.min, depicts that outer surface of cloth cannot work as the limiting factor.

Above discussion provides a valid argument that outer layer of clothing cannot affect the

evaporation process. It is the humidity level which is main reason of slow evaporation, since drop in

humidity is the main driving force. A fabric which can transfer moisture from inner side, means

from the skin surface can contribute in evaporation process. For better transport of moisture from

skin to outer layer needs a contact angle less than 900. Hydrophobic material cannot form this angle,

it is alway near to right angle, which affects its ability to transport the moisture. It shows that in

case of hydrophobic material force is required to transport from one side to other, more explicitly

speaking from skin to environment. It can be calculated by using the following equation.

25

Where:

h= Height of water ascent through the capillary

$ = Surface tension

r = Radius of the capillary

g= acceleration of the free fall

Figure 10: Wetting Angle

It can be observed by putting a drop of the cotton fabric which is free from any sort of finishes.

Water drop will spread easily and the contact angle will be quite less than 90 degree. It may be in

the range of 0-30 degree. In case the surface is hydrophobic it will be near to 90 degree. This angle

is a function of interface behavior among three phases; liquid, solid and the ambient atmosphere.

Polypropylene, polyethylene, polyester, teflon and many more plastic material have low surface

energy. Surface energy which is also called wet-ability is measured in dynes/cm. PP and PE have

less than 30 dynes/cm, which is quite insufficient fir wetting.

26

Due to low surface energy and consequently higher angle of contact inhibits synthetic fibers to

transport moisture from inner side to environment through capillary actions. Considering this

discussion it can be concluded that if the inner surface of the fabric is made of such fabric then there

is less chances that moisture will shift from skin to environment. The accumulation of moisture on

skin creates discomfort.

Table 3: Wetting Angle

Fiber Wetting Angle (0)

Polyethylene 114

Polyester and Nylon 6 70

Nylon 8 86

Nylon 10 94

Here there is a model which explains the moisture removal process. It is enough to understand that

material which have highest wetting angle is not capable to transport moisture from skin and not

suitable foe better comfort.

27

Figure 11: Heat and Moisture Flow

Papkov (1981) sums up the discussion and concludes that comfort depends upon the moisture

transfer from skin to the environment. This transfer depends upon the wetting power of the fibers

used, porosity (inter-fibre capillary) of the yarns, determination of fabric bulkiness and capacity of

reversible deformation of fabric. This can be achieved through a comprehensive consideration of all

factors. It is possible to achieve the required target by using different combination of fibers, testing

different fabric formations, application of various surface treating chemicals and making a suitable

design which should moisture transfer. One should not ignore various disadvantages of using

synthetic fibers, one is production of static charges, which can create uncomfort of human being.

Factors affecting Thermal Balance

There are nine possible factors which can contribute in achieving thermal balance. These factors

belong to five main areas:

10. Body metabolic activity (Physiological function and behavioral response or level and type of

activities)

11. Mass transfer (sweat evaporation and respiration system)

12. Heat transfer (through conduction, convection and radiation)

13. Ambient and radiant temperature

14. Level of insulation (clothing)

In this part of the article we will focus on physiological working and heat and mass transfer. Other

areas will be discussed later.

What we eat, it is converted into energy which is required for growth, tissue regeneration, operation

of body and physical activities. Our metabolic process has 20% efficiency, or we can say that our

body requires 20% of the energy produced through metabolic process all rest is converted into heat

and major part of the heat is rejected by body. To remove this extra heat there is a need to have a

direct contact of the body with environment so that it should give energy to environment through

radiation, conduction and convection. If environment temperature is already high then heat transfer

28

will not occur. In such case body temperature will keep on increasing and body will take help from

sweating process to convert the sensible heat into latent heat, which will convert moisture into

vapors. It is a known fact the evaporation reduces the temperature and ultimately skin will be

cooled down and thermal balance will be achieved. Barker (2002) explains Woo and Barker model

which is used to heat and moisture vapor transfer, which occurs simultaneously. This model is

written as:

Where:

Mn= Net metabolic heat which must be dissipated

Q= Heat lost through the clothing

H= Heat lost through thermal transfer

E= Heat lost through evaporation (mass transfer)

Woo and Barker (1988) calculate a comfort range with heat generated. The model is based on the

first criterion of clothing comfort which holds that the net metabolic heat generated (Mn) must be

dissipated through garments worn (Q).

Moisture Transfer and Clothing Comfort

The ability of a clothing material to transport moisture from sweat skin is crucial to perceived wear

comfort. A modified gravimetric absorbency testing system (GATS) is used at NCSU to measure the

moisture accumulation associated with the wicking of liquid moisture from sweating skin. The

GATS procedure measures demand wet-ability. The test indicates the lateral wicking ability of the

fabric, or the ability of the material to take up liquid in a direction perpendicular to the fabric

surface.

The GATS apparatus was modified to incorporate a special test cell and cover to assess absorption

behavior in the presence of evaporation. In this arrangement, liquid is drawn from a fluid reservoir

by the capillary action of the fabric. The hydrostatic pressure of the fluid delivery system is adjusted

by controlling the position of the sample platform. Liquid is delivered to the test material placed on

a porous plate. Numerous pins, distributed over the area of the test surface uniformly restrain the

test fabric. The amount (grams) of liquid siphoned from the reservoir is recorded as a function of

time. These data are used to calculate absorption capacities and rates, and the percentage of

29

moisture evaporated by the fabric. Applications of this device are discussed by Barker and Choi

(2001).

Thermal Equation of Human

Heat is an energy in transient. In case of human body it will be produced depending body

metabolic system and level of activities. According to laws of thermodynamics, equilibrium is the

ultimate end when two hot bodies or systems are put into contact. It will happen here and human

body will strive to have balance with the environment, it may be atmosphere or micro climate

created due to the clothing shield.

Following equation describes this process:

Where:

M = Metabolic rate of human body

E = Heat loss through evaporation and aspiration (wet heat)

R = Heat loss or gain through radiation

C = Heat loss or gain through conduction

S = Heat stored or consumed by body

30

Figure 12: Body Heat Balance

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

Human body is quite flexibly and has the highest adaptability. It acclimatize easily with

environment. Physiological conditions of human plays a significant role. If it is not in good

condition (overall health of the person), then there is a strong need to take measures to keep thermal

balance of human body. It may be change in ambient and radiant temperature, less or more clothing,

change in activities, etc.

There are certain differences in the final calculation of human body temperature. This variation is

with in a narrow limit. In addition, human body shows different temperature at different parts.

Furthermore, inner body temperature is different from the skin temperature. Nevertheless on the

whole 37.0 Centigrade is most acceptable and considered normal human body temperature of a

health person. There is a big variation in skin temperature. It may go down up to 40C and maximum

it can attain 40 0C. In both cases body feels discomfort. Generally, at 270C ambient temperature

body creates a thermal balance with the environment. In case of decrease in ambient temperature,

body starts to lose its heat and cold feeling signal is transmitted to brain, which takes necessary

action. It may be shivering of body. However, if the ambient temperature increases then body starts

to take temperature and again a discomfort is sensed and body starts sweating to lose its heat.

31

Considering this discussion it can be said that thermal imbalance is one of the reasons of

discomfort.

Figure 13: Radiation and Hunan Body

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

32

Figure 14: Reaction of Human Body and Temperature Variation

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

Figure 15: Association Between Temperature and Body Heat Loss

Fairy (1994)

33

Figure 16: Metabolic and Activities

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

34

Table 04: Metabolic Rate and Activities

Clothing Insulation and its Measurement

In case of imbalance between body temperature and ambient temperature, we take help of clothing

to attain balance which is highly required for thermal comfort. The main function of clothing is to

provide insulation between the body and environment to trap the heat inside so that there should be

no decrease in skin temperature. ISO 7730 explains the details of thermal clothing and provides

useful information how insulation works to provide thermal insulation for the protection of human

body from cold environment.

Clothing insulation properties depends upon type of fiber, yarn specification, fabric formation

process and designing of clothing. All is under the thermodynamics principles and laws. For

example, clothing which can trap air better insulator since air has lowest thermal conductivity.

35

Traditionally clothing insulation is measured in a unit which is called clo. It is equal to

0.155m2. 0C/W. This value is almost zero for a naked person and for a business two piece suit and

accessories it is nearly .05 clo. There is a list of different clothing and their insulation values given

in Table 5

Table 05: Clothing Insulation

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

36

Figure 17: Temperature and Clothing Insulation

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

37

Figure 18: Clothing Insulation Values

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

38

Figure 19: Temperature Variation and Effect on Human

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

Cellar et al.2008) take total heat transfer from the human body as the total of dry heat and wet heat.

They consider that heat loss through convection, conduction and radiation is dry heat loss, whereas

evaporation is wet heat loss. They have used a sweating manikin to calculate dry and wet heat loss.

39

Heat Transfer through Conduction, Convection and Radiation

Conduction

Figure 20: Heat Flow Through Conduction

Fourier Law is explains the heat transfer through conduction.

It is written in the following form:

It is important to note that heat transfer is not a scaler quantity, rather it is a vector quantity. It is

better to indicate direction with q. Normally x is used to indicate the one dimensional flow, however

for circular flow r put as subscript with q.

Convection

Newton law of cooling describes heat flow through convection. In this case heat is carried a moving

particle. It may be gases or liquid. Making water hot in a pan is best example to explain.

40

Following equations is used to describe the heat flow through convection:

q=h As %T

Where:

q = heat flow from surface of the substance (W)

h = heat transfer coefficient (depends upon the geometry of the substance) (Wm2 K-1)

As = Surface area in touch with environment (M2)

%T=TS-T! Temperature Difference (K)

Free Convection

Free convection is a common method in heat transfer process from human body. In forces

convection there is force which is used to keep in touch the medium by force. For example, fan is

used to take away moist from human body. In case of free convection, fluid or gas motion is due to

the buoyancy, which takes away the warmer fluid and cooler fluid becomes closer to substance

which has higher temperature. If we use any external force then convective rate will increase.

Free convection is well explained through Nusselt number. It is a ratio and dimensionless number

and indicates the conductive rate:

Where:

41

Q/A = Thermal flux (W/m2)

L =Length of the body

k = Thermal conductivity of the fluid or gas

&T = Temperature difference between the body and the surrounding fluid

We can have Nusselt number by using the Grashof number and the Prandtl number.

The Grashof number is given by2

Where:

" = Thermal expansion coefficient

L =Length of the body

V= Velocity

&T = Temperature difference between the body and the surrounding fluid

The Prandtl number indicates a ratio of the kinematic viscosity to the thermal diffusivity. For

example Pr number of air is nearly 0.7. It also depends upon temperature.

It is to note that the product, Gr*Pr is the Rayleigh number. Ra, is used to find the Nusselt number.

However, relationship between Nu and Ra is based on empirical experiments.

Value of Ra is about 1010 indicates transition region and turbulent region. Where

Nevertheless I is used in vertical plates or cylinders alike. It can be applied to do calculation of

human body.

42

Human skin temperature is nearly 34°C. After having clothes it may be changed increased or

decreased. For calculation, we consider that ambient temperature difference is &T=10°C (10K). We

take an adult man body height L=2 m. By taking Ra=8x109, Nu is nearly 200. It means that

conduction will be very low. As it is known that Nu is the ratio of convective to conductive thermal

transfer rates.

Since k=0.026 W/m/K for air

The convective thermal flux rate is

Heat Flow through Radiation

Radiation is the third way to transfer heat. In this case electromagnetic waves produced due to

temperature difference and heat is transfer from a hot body to a cooler body. In this case no medium

or matter is required to carry the heat. Heat transfer due to radiation is well described by the

following equation:

Emissive power of a surface:

E=$'Ts 4 (W/m2)

Where:

E= Emissive Power of surface of the of a substance

$= Stefan Boltzmann constant

' = emissivity of the substance. It is 1 for a black body)

Ts= Absolute temperature of the surface (K)

Third option of heat transfer is radiation and it can be calculated by Stefan-Boltzmann equation,

which is as under:

43

Where:

T0 = Ambient absolute temperature,

( = Emissivity

$ = The Stefan-Boltzmann constant

It has been worked out that skin works like a black body. Emissivity of skin and clothing is taken

nearly one. Its impact is less when &T is small compared to the ambient temperature, T0.

Wien's Law

This equation is used to predict temperature of any body by calculating the wavelength.

Where:

"max= Peak wavelengthT = Absolute temperature of the blackbodyb= Constant of proportionality, Wien’s displacement constant:

44

Figure 21: Wavelength and Light

Example: Wavelength of light emitted by human body:

.

Comparison of convective and radiative rates

We can measure ratio of convective to radiative transfer. It can be observed that its dependence on

temperature difference is not significant:

It is obvious from the above ratio that &T of 10°C is not making a big difference convection and

radiation. It shows that radiative heat radiative heat loss is double to the convective rate. However

forced convection can increase the convective heat transfer.

45

Literature provides many more results derived by researchers. There is a wide range of results and

all are based on some assumptions which ultimately lead to some differences in the outcome. We

can conclude all discussion that heat transfer from human body is primarily thorough convection

and then radiation. Very low percentage thorough conduction. In case heat transfer process fails to

create balance between human body temperature and ambient temperature, human body takes help

of perspiration and then mass transfer phenomenon takes place. There is a big analogy between heat

transfer and mass transfer.

Clothing Heat Transfer Coefficient

Clothing Heat Transfer Coefficient explains the all parameters which can influence the convection

heat transfer of clothing. It depends upon conditions of boundary layers, surface geometry and

nature of fluid.

Thermal Parameters of Fabric

One of the main functions of our clothing to work as thermal insulator. These parameters determine

the behavior of clothing under different circumstances. In the following lines we will discuss the

tests generally carried out to predict the behavior of clothing under different climatic conditions.

The main source all here under information is based on the lectures by Dr. Lubos Hes.

Thermal Conductivity

46

Thermal conductivity, which is normally denoted by k is a property of any matter to pass the heat. It

is mainly related with the chemical structure of the material and in case of gases, it is also a

function of pressure. However, in case of solid, it mainly depends upon the chemistry of the mass.

There are many ways to measure it. Its significance in clothing comfort cannot be ignored. Clothing

are made of different fibers. It may be natural or man-made. Different fibers have different thermal

conductivity. As said earlier that thermal conductivity as an indicator of the response of material,

when it will be exposed to any situation where there is a temperature difference between fiber and

the environment. It is quite easy to understand from the pan, used to fry an egg. Temperature of the

handle is quite low as compare to base of the pan. It is mainly due to the thermal conductivity of

material used for handle and for the base.

In the following there is a table showing thermal conductivity of different materials:

Table 06: Thermal Conductivity of Different Substances

Thermal conductivity equation ( in some equations k is used instead of )):

Where:

Q= amount of conducted heat

F = area through which the heat is conducted

* = time of heat conducting

%T = drop of temperature

$ = fabric thickness.

Thermal Diffusivity

47

Thermal diffusively or thermal diffusion is a property of any substance which indicates the ability

of the substance to adjust its temperature according to the environment. Higher thermal diffusivity

means that substance will adjust its temperature quickly. In more simple word, it is property of the

substance that depicts the rate at which heat diffuses through a substance. Furthermore, it is a

combine effect of thermal conductivity and its specific heat. Both are opposite. Higher thermal

conductivity will increase the body's thermal diffusivity whereas, high specific heat reduce the

thermal diffusivity.

Its equation is as under and unit is m+/s:

Where:

k : Thermal conductivity W/(m,K))

- : Density (kg/m.)

cp :Specific Heat Capacity (J/(kg,K))

In case of fabric it is the ability to heat flow through the fabric and how quickly fabric adjusts its

temperature according to the surroundings.

48

Table 07: Thermal Diffusivity of Some Common Materials

Source: J.P. Holman, Heat Transfer, as cited on Wikipedia

Thermal absorption

Thermal absorption is related to the cool-warm feeling of the surface of the fabric. This parameter is

related to the surface of the fabric. Cotton has higher value than synthetic fibers. Due to this reason

cotton is most suitable for summer as compared to synthetic fibers. Frydrych et al.2002) have

compared properties of different fibers and concluded that this parapets is mainly related to the

fabric surface so it can be altered by applying different finishings. Its equation is as under:

Where:

) = Thermal conductivity

- = Fabric density

c = The specific heat of the fabric

49

Frydrych et al.2002) have also found a correlation between fabric surface and the thermal

absorption. Smooth surface will have higher thermal absorption and gives cooler effect as compared

to a rough surface. Considering this observation, it can be deduced that twill fabric will have low

thermal absorption as compared to plain fabric. Also course yarn will have warm than fine yarn.

Thermal Resistance and Resistivity

Thermal resistance is a property of material which is directly proportional with thickness and

inversely proportional with thermal conductivity. Its equation is as under:

Where:

$ = Thickness

) = Thermal conductivity

It is reported by Frydrych et al.2002) that fabric with smooth surface has low resistance, whereas,

fabric with structured surface, like, twill will have higher resistance. This is the reason that when we

touch a smooth surface, we find it cool as compared to a rough surface. It is mainly due to the

thermal resistance difference. It is also important to note that certain finishes can alter the thermal

resistance by creating a change on the surface of the fabric. Peaching of the fabric is another

convincing example. After peaching fabric surface gives a cool feel.

Resistivity is a different concept, it relates to the object property and associated with the resistivity

and thickness of the object.

It is denoted as:

R= 1/k

Where:

R= Thermal resistance per unit area of the piece of material (m+K/W),

l = represents the thickness of the material (m), and

k = represents the conductivity of the material (W/mK)

50

Maximum and Stationary Heat Flow Density Ratio

Heat flows from hotter to a cooler body. It is denoted by heat flux, thermal flux, heat flux density or

heat flow rate. It is a flow of energy per unit of area, which is meter in SI units. It is expressed as

W.m- 2 and denoted a subscript q. It is vector quantity since it has both direction and magnitude.

Its equation is a sunder:

Where:

Q = Amount of heat

F = Area through which the heat is conducted

* = Time of flow.

In textile ratio of maximum and density heat flow ratio is a property which indicates certain

characteristics of the fabric. Frydrych et al.2002) have put forward that this ratio of cotton fabric is

much higher than the Tencel fabric. Maximum heat flow density indicates that when a cold fabric is

touched with skin a cool feeling will be observed. It is the reason that when we wear cotton in

summer, it gives a cool feeling, which is mainly due to the high ratio of maximum to stationary heat

flow of cotton. It is a function of thermal insulation and thermal absorption. Moreover, plain fabrics

have higher ratio as compared to rough surface.

Air and Vapor Permeability

Air and water vapor permeability is feature of fabric which is used to predict its contribution in

overall clothing comfort. Air permeability is amount of air passed through fabric in a certain period.

It is highly concerned with the flow of air from environment to body or vise versa. More air passing

means for heat and moisture exchange through convection. It depends upon the structure of the

fabric, yarn compactness, porosity of the fabric, cross-section and its shapes. In addition air and

moisture permeability have a great influence on thermal properties. This property is also under

influence of the type of weave and chemical application. Since both can alter the surface structure.

Equation of air permeability:

51

Where:

V= Capacity of the flowing medium

F= Area through which the medium is flowing

* = Time of flow

%p= Drop in pressure of the medium.

Thermal Equilibrium and Non-Physiological Factors

Other than physiological parameters, environment is the second most important factor. It relates to

air temperature, mean radiant temperature, air velocity, humidity. It may be an indoor or outdoor

environment. It is a well known fact that the temperature gradient is responsible for heat exchange

under natural conditions. Whereas, vapor pressure, which is measured as relative humidity is crucial

for moisture transfer under normal conditions. In case of indoor environment, we mange all above

four factors by using different methods. It may be heaters, air conditioners, fans, curtains, paints on

the wall, humidifiers or dehumidifiers. However in case of open environment, we prefer to go

where we can have environment suitable for our body. It may be sunlight in winter or shade of tree

in hot summer. In addition, we adjust our clothing to have a thermal balance between body and

environment. It is done by having more or taking off clothing according to the requirement. In the

following lines we will discuss all above mentioned factors in detail.

Air and Mean Radian Temperature

Temperature is a measure of average kinetic energy of any substance in any shape; solid, liquid, gas

or elementary plasma. It is linked with the movement of speed particle and their mass. High speed

of particles will have higher temperature. Mass of the particles have a direct affect of temperature.

Same mass if moves faster will have more K.E. and ultimately its average K.E. will increase which

can be measured as temperature of the whole particles. Kinetic Energy is core concept of mechanics

and has a lot of applications. It is a product of mass and square of velocity. It is also referred as

thermal energy of the whole system and generally known as heat. There are certain laws which

govern heat transfer phenomenon. In SI temperature unit is Kelvin (K), which is equal to -273.15

Centigrade. In thermodynamics K is most commonly used. In clothing comfort air temperature is

52

one of the main elements which is hard to ignore when we are talking about the comfort. It is the

parameters which leads the flow of heat and mass fro human body.

Radiant temperature which is not so popular as air temperature but it is equally important for

clothing comfort. It has not known to ordinary people only it is used in labs where clothing comfort

is measured. As it is obvious from the name it is related to radiation. Every substance emit radiation

and level of radiation depends upon its temperature along with its emissivity power. In any room,

there are many things, like walls, curtains, furniture. They take energy from same environment but

their radian temperature is much different from each other depending upon their thermal

conductivity and specific heat. Thereby their radiation is also different which is much associated

with the temperature (Planck’s law and constant). The mean radiant temperature of the things sitting

in a room have overall effect on air temperature. For example, In winter, walls will become cold if

they are not properly insulated. Thus they will radiate less and absorb more heat and ultimately will

effect the over all temperature. It is generally denoted as Mean Radiant Temperature (MRT).

MRT also depends upon the net exchange of energy (absorbency and reflection). It is proportional

to the difference of temperature of both items multiplied by their emissivity.

Where:

T = Surface temperature

/ = Surface exposure angle (relative to occupant) in degrees

MRT is an indicator of a uniform temperature of the surrounding of any object. For this reason it is

measured at all possible angles so that we may have a uniform radiant temperature. That is the

reason that it is not measured by a normal thermometer, rather a globe meter is used for this

purpose.

It is important to note that human body has very high emissivity and in measuring MRT, human

body is considered as black body. For measuring purposes, 1 is taken as emissivity of balk body and

then emissivity of any object is measured a ratio to black body, which is 1 at that temperature.

53

Emissivity of human body is .97, which is highest that any other known object available on earth. It

is quite near to 1, which is a hypothetical value. Any minor change in environment, human body

response in a great manner and ultimately there is a change in thermophysiological comfort, which

is mainly associated with the thermal balance. Consequently, there is a great impact on

physiological equivalent temperature (PET) and predicted mean values (PMV). These both factors

are major contributor in overall comfort of human being.

Globe meter, which is used to measure MRT is normal dry bulb thermometer in a case of 150 mm

diameter matte-black copper sphere. Its absorptivity is equal to human skin. Globe meter measures

MRT and it depends upon the heat transfer through convection and radiation. However, there is a

possibility to adjust the effect of convection by increasing the size of the dry bulb. Consequently,

we can have globe temperature (Tg) and air temperature (Ta). By increasing the air velocity, there

will be small gap between air and globe temperature, or MRT temperature.

Relative Humidity

Relative Humidity (RH) is an indicator of presence of water vapor presence in the air. Simply it is

the ratio of water vapor present in the air and the maximum amount of water vapor which air can

hold at that temperature or to attain saturated state.

It can be expressed as:

Where:

0 = Relative Humidity

ew = Water vapor in the air mixture

54

e*w = Saturated water vapor pressure

There are many meters to measure RH, the most common is a meter fitted with dry and wet bulb.

The difference is used to calculate the RH, which is given on chart. Application of RH measurement

is quite significant. It is better than the absolute humidity which just indicate the amount of vapors

present in air. It is also a known fact that there is a constant change in moisture with the change in

temperature. In clothing comfort measurement, RH is preferred on absolute humidity measurement.

Human body is thermal engine and produces heat on a regular basis. A part of the heat is used to run

its different functions and rest of the heat is shifted to atmosphere. Convection and radiation are the

main two ways to transfer heat. In case when human body produces extra ordinary heat due to any

physical activities, consumption of spicy food or extra ordinary increase in air and MRT , human

body produces sweat. This sweat is evaporated and resultantly a cooling effect is generated and

body achieves a thermal balance. For evaporation, the driving force is air velocity and RH.

In case when RH is quite high, the mass transfer (transformation of water into vapors) becomes

very slow. However, when there is a dry environment, water evaporates quickly. It is generally

observed that people feel less comfort in humid atmosphere as compare to highly humid

atmosphere. Due to this human body feels any change in RH very strongly and sends signals of

comfort or discomfort to brain. It is also important to note that presence of water on human skin

increases its skin temperature, since water takes a lot of heat generated by the human body and

holds it to increase its temperature. This way we find a regular storage of heat on the skin. In such

case the comfort is only possible by removing the moist from the skin by using air velocity or by

changing RH in the environment. In such cases we use fan or air conditioning machine to reduce

the skin temperature which provides ultimately comfort.

Bending Rigidity

B= E.I

I= b.h3

By increasing height bending rigidity increase three times

Power (W)= Amp* Volts (I*V)

Air velocity (#)1/Moisture resistance

Absolute water vapor permeability= Pa m2. W-1

55

Air Velocity and Comfort

Air circulation or movement increases heat transfer due to convection. Nevertheless, air movement

also serves many other purposes, like, removal of odor or any other unpleasant smell. It also takes

in fresh air which has normally higher percentage of oxygen and desired fragrance. If there is no air

circulation, then there are bright chances that unpleasant smell will increase and uncomfort will be

observed. In addition our skin also needs oxygen.

Table 08: Air Velocity and Reaction

Source:http://media.johnwiley.com.au/product_data/excerpt/53/04716896/0471689653.pdf.

Heat/Mass Transfer and Role of Textile

Özdi et al.2007) have studied impact of different properties of yarn on thermal properties and have

linked it with clothing comfort. They conclude that combed and fine yarns have lower thermal

conductivity higher vapor permeability. Fabric made from such yarn give warmer feeling. Such

fabrics also have lower thermal absorptivity. Literature provides many more studies which explain

the correlation between thermal properties of fabric and warm and cool feeling.

Thermal of fabric governs the flow of heat from human body to environment and vise versa. A man

in desert where the temperature is at its peak will prefer clothing which should not allow heat to

cross the clothing layers from outside to inner side. Since outer temperature is quite high as

compared to body temperature. In such case best clothing are which have lowest thermal

conductivity as well as lower thermal absorptivity and higher resistance. Such clothing will give

56

cool effect. However, in a case where temperature is freezing, a person needs such clothing which

should not allow to pass his or her body heat from inner side to environment to keep the body

warm. In such cases we also need a clothing with lower thermal conductivity, lower thermal

absorptivity and higher resistance. Such clothing will give a warm feeling. All above discussion,

supports the idea that clothing with low thermal conductivity and lower thermal absorptivity and

higher resistance are most suitable. Cotton, which is most common in use and highest percentage of

consumption has the lowest values of thermal conductivity and thermal absorptivity.

The second factor which plays an important role in keeping our body warm is the capability to trap

air. We prefer wool in winter because it keeps our bodies warm in winter. Wool has almost same

thermal conductivity as cotton but it gives higher warm feeling. It is mainly due to the wool fiber

structure which is highly capable to capture air. It is a known fact that air has the lowest thermal

conductivity and protect human body from cool. In case the wool is fine and have a dense weaving

it also gives cool effect.

Polypropylene is a synthetic fiber which possess the lowest thermal conductivity almost near to

cotton and wool. It is much appreciated in making socks, legging, vests etc to give a warm feeling

in winter. One can find clothing made of PP in market, even denim trousers, sweat shirts are also

available.

Above discussion leads to the fact that if we want to keep ourselves warm, we need a material with

low conductivity and capability to trap air. For this purpose fleece made of PP is the best product.

Even fleece made of polyester also serves this purpose. In addition PP and polyester does not lose

their thermal conductivity behavior when they are wet. Whereas, cotton shows a higher thermal

conductivity when it gains moisture. This is the main reason that people have developed fleece

made of polyester and PP inside so that it keep its thermal conductivity intact even there is a

moisture. PP is more effective in this case since its moisture absorbency is near to zero and it

receives no impact of moisture and shows low thermal conductivity.

Multi Fiber Fabric in Clothing Comfort

As it is obvious from Tables (1,2,3) that different fibers have different properties. It is not possible

to construct any fabric able to work in every situation due the huge variation and diversity in their

fundamentals characteristics. However, it is quite possible to blend different fibers to get most

57

optimum results. Blending of two different fibers to make yarn is quite common. Another way is to

use two or more than two different yarns in fabric formation. Along with that adhesion of two or

more than two lyres of fabrics is another way to have better results. Different yarns on opposite

sides is another solution. Moreover, filling of fiber between two layers of fabrics also serves certain

demands. Filling of staple fiber in quilts is a common example.

Wu et al.2009) and Wu and Fan (2008) have conducted studies to evaluate impact of blending of

different fibers and concluded that it is quite possible to achieve better results by combining more

than one fibers. Wu et al.2009) tested 10 different shirts made of different fibers and found that

there is a great variation in the results which is primarily due to fiber properties. They did subjective

evaluation by following proper protocol in a controlled chambers. It was observed that natural

fibers are more damper and more thermal than regenerated fibers. Wu et al.2009) have proposes that

clothing made by assembling of different fabrics exhibits much better thermal and moisture balance

and boost overall clothing comfort perception. Wu and Fan (2008) put different layers to develop a

unique fabric and found that hygroscopic pads plays a significant role in controlling moisture

management. This is mainly due to contrast thermal and moisture control properties of different

fibers.

Modification of Fibers and Thermal Parameters

Although chemical structure of fibers is the core factor responsible for heat transfer in clothing

comfort process. Largely, our focus is to have blend of different fibers. Schacher et al.2000) have

studied the difference between traditional polyester and microfibers. They report that microfibers

exhibits low thermal conductivity while keeping all other parameters same. Lower conductivity

provides a warm feeling which in some cases highly desired. This study is an evidence that even

having same chemical structure, change in the physical structure helps improve the moisture and

thermal management. Tzanov et al.1999) conducted tests of different fabric after treating them with

various chemicals. They conclude that surface modification affects thermal properties of fabrics.

Fabric Properties and Comfort

There are number of properties of fabric which plays a significant role in overall comfort. Some are

listed below:

15. Bending rigidity

58

16. Flexural rigidity

17. Thickness

18. Grams per meter square (density)

19. Surface smoothens

20. Compressibility

21. Stretchability

22. Shear rigidity

23. Bulkiness

24. Surface friction

25. Warm and cool effect

26. Air permeability

27. Moisture permeability

28. Absorbency

Clothing Moisture, Thermal and Air Transfer at Wetting State

Water has higher thermal conductivity as compare to most of natural and man-made fibers.

Moreover, when fibers gains moisture, consequently their thermal conductivity also increased and

thermal resistance drastically decreased. Hes (2008b) has conducted an in-depth studies and

conclude that moisture replaces air from the fabric pores. It is a known fact that air has quite less

thermal conductivity as compared to water. Moreover water is absorbed by certain fibers and this

also increase the thermal conductivity.

From the presented results follows, that with increasing fabrics humidity their thermal resistance

can even significantly decrease. This is caused by substituting of the air in pores by water with

higher thermal conductivity. The ALAMBETA instrument proved to be suitable for the

investigation of thermal properties of fabrics in wet state. It was found, that some fabrics with

certain structure and composition keeps higher level of thermal resistance even in wet state. Hes

(2008b) also identified that air and moisture permeability decreases. Nevertheless it was found that

in some fabrics change is not so significant and it is compensated with other phenomenon.

Effect of moisture on thermal, moisture and air permeability properties needs a great attention of

the fabric designers since it can alter the overall clothing comfort level.

59

Objective Measurement of Clothing Comfort: An Effort for Precision

The significant of objective measurement is becoming popular even there are many questions of its

accuracy and adaptation are attached with this concept. There are a number of testing machines

have been made to have better results. NCSU have developed a sweating manikin to measure effect

of moisture on the thermal balance. Such system was also devised by Meinander. Kuklane et al.

(2004) have reviewed different manikins based on their sizes and functions. This review provides

quite useful information and reveals the struggle to have better results from testing before

conducting subjective evaluation.

Barker (2002) raises point of complexity of human body and mind, while we are applying

scientifically based approaches for objective measurement of fabric or its next shape clothing. It

should be given a due weight. Because comfort is not a function of some mechanical properties of

fabric tested in isolation. There is a strong need to intervene the human perception process, which is

quite influenced by many factors associated with people and have a significant variation from

person to person. Even same person would have different reaction if there is a change in context.

Human will use his or her personal feelings, preferences, experiences, state of mind, level of

emotion, education, training as filters before reaching on any conclusion.

Study of Kuklane et al. (2004) points out performance variation problem associated with manikins

which are widely used in objective measurements. There is a drastic but acceptable variation in the

structure of male and female manikins. It shows that in real life difference between the bodies of

male and female is also visible even in manikins. Such observations support the point that reliance

on objective measurement is not enough to declare any product best fit for human being. This study

recommends that there is need of utmost care while interpreting the results by using different

manikins of different sizes and of different fitness along with of male and female.

There are thermal manikins which are equipped with a system to produce moisture from different

parts. Barker (2002) reports that manikin made at NCSU can produce moisture from 189 different

60

points (human body has more than 2.6 million sweat glands). Thermal manikins are used to

measure moisture and heat loss while having different type of clothing.

There are a number of tests under practice to test the clothing comfort. All these tests are carried out

to measure some mechanical and electrical changes. Nevertheless all such tests are being adopted

after doing many simulations. A number of tests by using some subjects were found having a

significant correlation. Thereby, we can rely on these tests to a certain length. There is a long list of

such instruments. However, we will list down here some most common instruments being used to

predict clothing comfort.

Kawabata Evaluation System (KES)

KES can measure the following parameters of fabric:

29. Warm cool feeling

30. Smoothness of surface

31. Bending rigidity

32. Shear rigidity

KES work on different principles. For example, it was investigated by Kawabata that there is

significant correlation between transient heat flux and the warm or cool effect. Base on this

principle, KES measure the warm or cool effect of the fabric.

Alambeta

Dr. Lubos Hes has patent of this testing machine. It measure the thermal conductivity coefficient,

heat transfer resistance, height of the fabric, heat flux peak, thermal absorptivity. In this machine

fabric is packed between the two plates which have 10 degree difference of temperature. During a

short period contact heat flow takes place and all parameters are measured.

Permetest

Dr. Lubos Hes has its patent and the main function of this machine is to measure vapor permeability

of fabrics.

61

Figure 22: Fabric Touch Tester

J.Y. Hu, Lubos Hes Y. Li, K.W. Yeung and B.G. Yao have developed “Fabric Touch Tester (FTT)”,

which is used to integrate evaluation of thermal–mechanical sensory properties of polymeric

materials. This instrument measures, records and analyses thermal and mechanical sensory

stimulations and propagations occurred while clothing becomes in touch with the human skin. FTT

can be used to predict many mechanical properties of clothing, like smoothness, softness,

prickliness, warmth and dampness. In stead of the highest precision level of FTT, even then there is

a need of subjective evaluation of the clothing.

Figure 23: Fabric Touch Tester

62

Hohenstein Institute

Hohenstein Hohenstein Institute working since 1946 and provides services to measure clothing

physiology. This institute is using different methods of clothing physiology to develop different

products. For example, items of clothing, as well as bedding and sleeping bags, shoes, socks etc.

(for information:www.hohenstein.de)

Figure 24: Working at Hohenstein Institute

Sensorial Comfort Testing at NCSU

NSCU has developed a testing machine which tests the sensorial comfort. It measures moisture

transport and vapor buffering capacity. There is a dynamic sweating plate in this machine, which is

used to assess the impact of microclimatic changes in fabric due to pulsed heat and moisture

changes. Finally changes in micro climate and dynamics of fabric are processed and based on the

results sensorial comfort can be predicted.

63

Figure25: Dynamic Sweating Machine at NCSU

Moisture and Wicking Test

NCSU has developed a Gravimetric Absorbency Testing System (GATS) to measure the moisture

presence and its wicking from the sweating skin. This testing machine works on the principle of

demand wet-ability. From this machine we can measure the ability of fabric to transport moisture

from skin to environment.

Figure 26: Gravimetric Absorbency Testing System at NCSU

64

Figure 27: Sweating Manikin used at NCSU

Figure 28: Walking manikin used by XIaoming Qian and Jintu Fan

65

Nondestructive Testing of Clothing

Hes (2008a) has provided details of the some instruments which are capable to carry tests without

destruction of the clothing. These tests are possible to conduct after making clothing.

Subjective Measurement and its Limitation

As discussed in previous pages that there are a number of machines available to measure different

thermal and mechanical properties of different fabrics. Nevertheless these tests are all incredible.

There is one short coming associated with these tests that they cannot predict the overall comfort.

They can be used to predict certain properties. For example, wicking properties, surface

smoothness, etc. Even though there are many factors which are missing, particularly, fitting and

cutting of clothing. If there is designing or fitting problem, this will supersede all mechanical and

thermal comfort.

The second important point is that the human being which is final user of the product itself has

immeasurable variation. One temperature may suits to a young person but may not to an old person.

Keeping all difficulties in view subjective testing by using human being as a subject is the most

common method applied to measure clothing comfort. If we find a strong correlation between two

then it is considered as the success of the tests.

Subjective measurement is not free from errors. Rather it has more chances of errors. However, in

spite of many drawbacks, it is the final way to test the clothing. The main issue is the creation of the

environment which has a great analogy with the real world. We can maintain temperature, humidity,

air flow in a closed chamber. In real world there is a huge dynamical changes in all three

parameters. There is no way to accommodate such changes. Clothing may be highly comfortable at

a certain temperature and humidity, but sudden changes may make it uncomfortable. The second

issue is the selection of the subjects. Every human being is quite influenced by the age, experiences,

metabolic rates, mental and physical health, education, training, etc.

There are many places where subjective evaluation is being carried out. They have tried their level

best to have more accurate results by developing highly controlled chambers and doing lot of care

66

in selecting of people. This evaluation is mainly used to correct the clothing and fabric and this

leads to develop new fabrics and clothing.

NCSU has developed a well equipped labs to evaluate the fabric and clothing through subjective

evaluation. For this purpose they use different protocols. In some cases five-period test sequence is

used (activity-rest). There is no final and uniformly acceptable protocol, rather it depends upon the

type of clothing and institute itself.

Table 09: Overall Comfort Rating

Model for subjective evaluation provided by Jason Wickwire and associates

Literature provides many reports which are big critics of subjective evaluation. Cent and Dearb

(2001) consider that chamber developed to measure subjective perception are not a successful

experiment, rather such chambers fail to provide an experimental realism. They prefer field studies,

which of course are not free from errors, but their error is much less than the chamber evaluation.

The main difference is absence and deletion of contactual factors, which are mainly associated with

the human. The emotion, competing sense, adapting attitude, adjustment of posture and clothing are

few factors which cannot be taken in chambers. Subjects selected in chambers lack in such matters

and they just try to perform as a machine without any sort of soft issue of the evaluation.

67

Models for Clothing Comfort Prediction

Wong and Li (ND) have developed a hydride model. In my personal view this looks one of the best

model which have taken maximum factors. Writers have used objective and subjective testing, both

to develop this model. They developed 33 different fabrics and carried out their tests. For subjective

testing they involved 38 adults and followed the standard procedures and protocol. They used three

different models (HM-LM, HM-NN and HM-FL). In this model writers measures eight factors

(objective measurement, five mechanical and three related to transport of mass and heat). They took

three sensory factors (thermal-wet comfort, tactile comfort and pressure comfort). Researchers

found a high correlation between objective and subjective predictions and summed the whole work

in the following words, “Based on the study in this paper, it can be concluded that fabric physical

properties can be used to predict overall clothing comfort with hybrid predictive models….

Figure 29: Hybrid Modeby Wong and Li (ND)

Raj and Sreenivasan (2009) Raj and Sreenivasan (2009) have successfully developed index to

predict the clothing comfort.

68

Sampling scheme (Raj and Sreenivasan, 2009)

Raj and Sreenivasan (2009) present their findings which are quite invaluable. This outcome can be

used to predict the overall clothing comfort behavior. Summary of their result is as under.

Fabric made of yarn which has been produced by using fine and longer fiber exhibits better

extensibility and higher tensile energy and such fabric need less bending force and have lower

compressional energy. Moreover, such type of fabric has lower bending recovery. Researcher also

point out that increase in twist can increase bending rigidity, extensibility, compressional energy,

and residual strain. On the other hand, it will decrease the shear rigidity, hysteresis, and tensile

resilience. Considering this observation it can be inferred that twist level can be used to predict

certain quality parameters of the fabric. Research further explains that finer yarn is source of better

smoothness and softness, which plays an important role in overall comfort.

Raj and Sreenivasan (2009) have also measured impact of different weaving types and found a

strong correlation between weaving design and mechanical properties. They have also studied affect

of vapor permeability, fabric thickness, fabric surface friction on comfort. Considering all this, they

have presented a Total Wear Comfort Index, which can be used to predict overall clothing comfort.

69

All above discussion provides a convincing arguments in the favor development of some models

able to predict overall clothing comfort. This effort is still on and in our view these model can serve

purpose to a certain extent. These models can be used to develop new fabrics. The matter of fact is

that subjective evaluation along with the objective testing of the product is the most reliable method

to predict the overall comfort level, which could have more than 80% accuracy and acceptance

level length.

Overall Comfort: A Desired Outcome

All above discussion is to explain the clothing comfort phenomenon and factors affecting it. As

concluded by Barker (2002), objective and subjective measurements, both are incredible. They are

capable to server certain purposes. Although non of these is fully able to predict the overall

comfort. Testing machine can tell thermal conductivity of any fabric, friction of the fabric surface

and many things more. Human can give his or her observation about the skin sensation, warm or

cool effect, etc. but not the overall comfort. We cannot ignore the role of cutting and designing,

fitting. Human body has lot of shapes and there is a big variation among women, men, young

people, kids and even people living in different parts of the world.

Table 10: Wear Trail Protocol at NCSU

70

Baker (2002) provides list of different sensations. It is obvious from the radar chart that perception

about different factors are is quite different from each other.

Figure 30: Human Sensation

Source: Baker (2002)

71

References

Barker, R. L. (2002). From fabric hand to thermal comfort: the evolving role of objective

measurements in explaining human comfort response to textiles. International Journal of

Clothing Science and Technology, 14(3/4), 181-200.

BARITZ, M., CRISTEA, L., COTOROS, D., & BALCU, I. (2008). Human Body Temperature

Monitoring System to Analyze the Comfort During Manufacturing Process. Paper presented

at the International Conference 6th Workshop on European Scientific and Industrial

Collaboration on promoting Advanced Technologies in Manufacturing.

Celcar, D., Meinander, H., & Gersˇak, J. (2008). Heat and moisture transmission properties of

clothing systems evaluated by using a sweating thermal manikin under different

environmental conditions. International Journal of Clothing Science and Technology, 20(4),

240-252.

Cenaa, K., & Dearb, R. d. (2001). Thermal comfort and behavioural strategies in office buildings

located in a hot-arid climate. Journal of Thermal Biology, 26, 409-414.

Fairey, P. W. (1994). Passive Cooling and Human Comfort. FSEC Publication DN-5.

Frydrych, I., Dziworska, G., & Bilska, J. (2002). Comparative Analysis of the Thermal Insulation

Properties of Fabrics Made of Natural and Man-Made Cellulose Fibres. FIBRES &

TEXTILES in Eastern Europe, 40-44.

Hes, L. (2008). Non-destruction determination of comfort parameters during marketing of

functional garment and clothing. Indian Journal of Fiber and Textile Research 33, 239-245.

Hes, L. (2008). Heat, Moisture and Air Transfer Properties of Selected Woven Fabrics in Wet State.

Journal of Fiber Bioengineering and Informatics 969-976.

Hollies, N. R. S., Custer, A. G., Morin, C. J., & Howard, M. E. (1979). A Human Perception

Analysis Approach to Clothing Comfort. Textile Research Journal, 49(10), 557-564.

Kaplani, S., & Okur, A.E. (2008). THE MEANING AND IMPORTANCE OF CLOTHING

COMFORT: A CASE STUDY FOR TURKEY. Journal of Sensory Studies, 23, 688-706.

72

Kuklane, K., Sandsund, M., Reinertsen, R. E., Tochihara, Y., Fukazawa, T., & Holme'r, I. (2004).

Comparison of thermal manikins of different body shapes and size. Eur J Appl Physiol(92),

683-688.

Y., L. (2001). The Science Of Clothing Comfort Textile Progress, The Textile Institute, 31(2).

Özdil, N. n., Marmaralı, A., & Kretzschmar, S. D. n. (2007). Effect of yarn properties on thermal

comfort of knitted fabrics. International Journal of Thermal Sciences (46), 1318-1322.

Papkov, S. P. (1981). Some aspects of comfort evaluation of clothing made from fabrics based on

synthetic fibres. Fibre Chemistry, 12(4), 219-222.

Raj, S., & Sreenivasan, S. (2009). Total Wear Comfort Index as an Objective Parameter for

Characterization of Overall Wearability of Cotton Fabrics. Journal of Engineered Fibers and

Fabrics, 4(4).

Schacher, L., Adolphe, D. C., & Drean, J.-Y. (2000). Comparison between thermal insulation and

thermal properties of classical and microfibres polyester fabrics. Journal: International

Journal of Clothing Science and Technology, 12(2), 84-95.

Tzanov, T., Betcheva, R., & Hardalov, I. (1999). Thermophysiological comfort of silicone softeners-

treated woven textile materials. International Journal of Clothing Science and Technology,

11(4), 189-197.

Wu, H., & Fan, J. (2008). Study of heat and moisture transfer within multi-layer clothing

assemblies consisting of different types of battings. International Journal of Thermal

Sciences (47), 641-647.

Wu, H. Y., , W. Y. Z., & Li, J. (2009). Study on Improving the Thermal--Wet Comfort of

Clothing during Exercise with an Assembly of Fabrics. FIBRES & TEXTILES in

Eastern Europe-, 17(4), 46-51.

Y., L. (2001). The Science Of Clothing Comfort Textile Progress, The Textile Institute, 31(2).

73

Bibliography

Cardello, Armand V; Winterhalter, Carole; Schutz, Howard GCardello, Armand V; Winterhalter,

Carole; Schutz, Howard (2003) Predicting the handle and comfort of military clothing fabrics from

sensory and instrumental data: Development and application of new psychophysical methods.

Textile Research Journal

Cumo F., Gugliermetti F. & Guidi G. (). Evaluation of physiological comfort index for workers

wearing protective clothing in nuclear or other harsh environments

Y Li and A S W Wong .Clothing biosensory engineering. Woodhead Textiles Series No. 51

Celcar Damjana; Meinander Harriet and Gersˇ ak Jelka (2008).Heat and moisture transmission

properties of clothing systems evaluated by using a sweating thermal manikin under different

environmental conditions. International Journal of Clothing Science and Technology Vol. 20 No. 4,

pp. 240-252

Fan J and Hunter L.(ed) (2009).Engineering Apparel Fabrics and Garments. Taylor & Francis

LLC. USA

Hipler U.-C. and Elsner P (eds) (2006): Biofunctional Textiles and the Skin. Curr Probl Dermatol.

Basel, Karger, , vol 33, pp 51-66

Holmr Ingvar (2004) Cold but comfortable? Application of comfort criteria to cold environments

Indoor Air; 14 (Suppl 7): 27–31

Kaplansibel and Okurays¸ E (2008). THE MEANING AND IMPORTANCE OF CLOTHING

COMFORT: A CASE STUDY FOR TURKEY. Journal of Sensory Studies 23 pp. 688–706.

Min Li, Dong-Ping Li, Wei-Yuan Zhang, Xiao-Zhong Tang,(2009). Factor Analysis on Subjective

Attributes Affecting Knitted Fabric's Comfort Sensation. First International Workshop on Database

Technology and Applications. pp.695-698

74

Ruckman J.E.; Murray R. and Choi H.S. (1998). Engineering of clothing systems for improved

thermophysiological comfort The effect of openings. International Journal of Clothing Science and

Technology, Vol. 11 No. 1, 1999, pp. 37-52.

Satsumoto Yayoi; Murayama Chikako, and Takeuchi, Masaaki (2009). Effect of Moisture Sorption

of Underwear Material on Clothing Microclimate in a Hot Environment Heat Transfer—Asian

Research 38 (1), 2009

Wilson Cheryl A. and Laing M. Raechel (1995). Investigation of Selected Tactile and Thermal

Characteristics of Upholstery Fabrics. Clothing and Textiles Research Journal, Vol. 13, No. 3,

200-207 (1995)

YAN ,YUK YEE AND OLIVER , JOHN E.(1995). THE CLO : A UTILITARIAN UNIT TO

MEASURE WEATHER/CLIMATE COMFORT. INTERNATIONAL JOURNAL OF

CLIMATOLOGY. VOL. 16, 1045-1056

75