Presentation on "Thermal Comfort".

1. Presented by
Mohammad Habibur Rahman
(2016-2-5-003)
Advance Textile Studies (TE-590)
Dept. of Textile Engineering Management.
Msc in Textile Engineering, Batch 6th.
Bangladesh University of Textiles.
Presented to
Md. Mazedul Islam
Asst. Professor
Dept. of Apparel Engineering.
Bangladesh University of Textiles.
Presentation on “Thermal Comfort”

2. Comfort is a sense of physical or psychological ease, often
characterized as a lack of hardship.
comfort is a pleasant state of physiological, psychological, neuro-
physiological and physical harmony between a human being and the
environment.-Slater (1985).
Clothing comfort is a state of satisfaction indicating physiological,
psychological and physical balance among the persons.
What is Comfort?

3. The condition of mind which express satisfaction
with the thermal environment and is assessed by
subjective evaluation (ISO 7730).
Thermal Comfort is those characteristics of the
environment which affects a persons heat
loss/gain.
In terms of body sensations, thermal comfort is
the sensation of hot, Warm,
slightly warmer,
neutral, Slightly cooler,
cool and cold.
Thermal Comfort?

4. There are two main factors that affect clothing Comfort.
 External Factors: The environmental temperature,
moisture, wind, cultural and social influences which affect
the clothing comfort.
 Internals Factors: In terms of body sensations, thermal
comfort is the sensation of hot, Warm, slightly warmer,
neutral, Slightly cooler, cool and cold.
Factors that affect clothing comfort

5.  Environmental factors:
1. Air temperature. 2. Radiant temperature. 3. Air velocity. 4. Humidity.
 Personal factors:
5. Clothing Insulation. 6.Metabolic heat.
Six basic factors of thermal comfort

6. 1.Air Temperature: This is the temperature of the air surrounding the
body. It is usually given in degrees Celsius.
2.Radiant temperature: Thermal radiation is the heat that radiates from
a warm object. Radiant heat may be present if there are heat sources in an
environment.
3.Air velocity: This describes the speed of air moving across the employee
and may help cool them if the air is cooler than the environment.
4.Relative Humidity: Relative humidity is the ratio between the actual
amount of water vapor in the air and the maximum amount of water vapor that the
air can hold at that air temperature. Relative humidity between 40% and 70% does
not have a major impact on thermal comfort.
5.Clothing insulation: Thermal comfort is very much dependent on the
insulating effect of clothing on the wearer. Clothing is both a potential cause of
thermal discomfort as well as a control for it as we adapt to the climate in which
we work. You may add layers of clothing if you feel cold, or remove layers of
clothing if you feel warm.
6.Work rate/metabolic heat: The more physical work we do, the more
heat we produce. The more heat we produce, the more heat needs to be lost so we
don’t overheat. The impact of metabolic rate on thermal comfort is critical.

7.  The body uses thermo-regulatory mechanisms to compensate the
gain or loss of heat to keep body temperature in equilibrium. This
system is known as the hypothalamic thermostat, which "tells" the
body to increase or decrease the temperature, in accordance with
thermal needs.
Thermal comfort is satisfied with the thermal environment and does
not need to use thermo-regulator mechanism. When temperature is
more or less than this body feels discomfort, as a result human body
needs some external agency to maintain this temperature and clothing
is one of the most common devices to provide comfort in this regard
Mechanism of Thermal Comfort

8. Heat Balance
The human body tries to maintain a constant core temperature of
about. 37 Degree Celsius. The efficiency of the human organism is
such that of the energy taken in as food only 15 - 30% is converted
into useful work with the remaining 70 - 85% of the energy being
wasted as heat. The heat balance is mathematically expressed as
below :
Q = M ± R ± C∞v ± C∞d – E
Where,
Q = Heat gain or loss.
C∞v = Convective gain or loss.
C∞d = Conductive gain or loss.
E = Evaporative loss.
M = Metabolism.
R = Radiant gain or loss.

9. There are five mechanisms like conduction, convection, radiation,
evaporation and respiration that allow the body to lose heat to the
environment in order to maintain its thermal balance.
Heat Loss

10. More Pictures to be Clear.

11.  The appropriate use of textile materials.
 Creativity in design.
 Attachment of special wearable devices into the garment system.
 The appropriate use of Textile materials.
Clothing thermal comfort relates to many different factors of textile
materials, such as:
o Fibre types.
o Yarn type.
o Yarn smoothness.
o Fabric structure.
o Fabric thickness and
o Special material.
Different Approaches to thermal comfort.
Textile Fiber
Moisture Regain
(MR%)
Moisture Content
(MC%)
Cotton 8.5 7.34
Jute 13.75 12.1
Viscose 11.0 9.91
Silk 11.0 9.91
Wool 16.0 13.8

12. Appropriate use of Textile Fibres:
o The moisture absorbency of the fibre is directly related to the
moisture regain of the fibre or fabric.
o In the normal situation, fibre with higher moisture regain could
absorb more moisture and heat from the body.
o Natural fibres like wool and cotton have been shown to have higher
ability to absorb large amounts of moisture due to their hygroscopic
properties.
Appropriate use of Fabric Construction:
o Fabric structure and its thickness influence the heat and moisture
transfer and hence thermal comfort.
o This is because fabric structure and thickness affect the air and
moisture permeability, which play a significant role in heat and
moisture transfer.

13.  Special undergarment construction to improve ventilation
Designers have developed special constructions between fabric layers
with a series of parallelised ribs or cords to form the air channels. hea
and moisture transferred from the undergarment could be released
from this air gap.
 Use of Single or Multiple Fabric layer in the construction
The number of fabric layers also contributes to the thermal insulation
and moisture vapor resistance of the clothing system. In general,
more layers create additional layers of still air resulting in higher
thermal insulation and moisture vapor resistance compared to a single
layer of fabrics.

14.  Moisture management fabric
The ability of a garment to transport moisture away from the skin to
the garment's outer surface. This action prevents perspiration from
remaining next to the skin.
 Waterproof breathable fabrics:
It is consist of an outer layer called the “face fabric”, usually made of
nylon or polyester, and a laminated membrane or coating, usually made
of ePTFE (expanded Polytetrafluoroethylene, also known as Teflon) or
PU (Polyurethane) which resist liquid water passing through, but allow
water vapour to pass through.

15. There are some established way of garments design basic for increasing
thermal comfort.
o Ventilated clothing.
o Ventilated garments having protective shield layers.
o Garment ventilation apertures with cover flap.
o Garment with structural vent.
o Garment with comprised of cords.
 Garment Design for comfort:
Garment fit is considered as one of the elements that influence
thermal insulation and evaporative resistance and there has been a
clear relationship of garment fit and clothing insulation.

16.  Ventilated clothing.
 Ventilated garments having protective shield
layers.
 Garment with comprised of cords.

17. o Air cooling system
o Ice or Cold Pack System
o Liquid cooling system
 Special wearable devices for thermal Comfort.
Air Cooling:
During hot weather, people used electric fans to keep the
body cool before the invention of air conditioning systems.
The fan system has been adopted in the garment system for
specific occasions. Normally these fans are lightweight and
small enough to be installed on the garment.

18. Ice or Cold Pack System
• This system uses ice or a gelled coolant to keep the body
cool. the ice packs or gelled coolants require replenishment. It
is not suitable for daily use.
Liquid cooling system
Liquid cooling systems require a fluid reservoir, a circulating pump and
connecting hoses which attach to the garments. The cooled liquid is
circulated through the garment and then returned to the reservoir for
re-chilling. This circulated mechanism provides lower temperatures to
the wearer.