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THERMAL PROPERTIES OF SOME SELECTED MATERIALS USED AS CEILING
IN BUILDING
BY
SA’AD ABDULLAHI SULEIMAN
SCI/2014/ 0878
A PROJECT SUBMITTED TO THE DEPARTMENT OF PHYSICS, FACULTY OF
SCIENCE, FEDERAL UNIVERSITY DUTSIN-MA, KATSINA STATE, IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF DEGREE OF
BACHELOR OF SCIENCE (B.Sc.) IN PHYSICS.
OCTOBER, 2017
ii
DECLARATION
I, SA’AD ABDULLAHI SULEIMAN with matriculation number (SCI/2014/0878) hereby
declare that this work titled “THERMAL PROPERTIES OF SOME SELECTED
MATERIALS USED AS CEILING IN BUILDING” is an original research written by me
under the supervision of MR. ATSUE TERSOO of the Department of Physics, Federal
University Dutsin-Ma. The research has not been submitted for the award of any degree or
diploma by any other person(s) or institution(s), and all sources of information are specifically
acknowledged by means of references.
Student’s Signature Date
iii
CERTIFICATION
This research entitled “THERMAL PROPERTIES OF SOME SELECTED MATERIALS
USED AS CEILING IN BUILDING” by SA’AD ABDULLAHI SULEIMAN meets the
requirement governing the award of the degree of Bachelor of Sciences (B. Sc.) in Physics,
Federal University Dutsin-Ma, and is approved for its contribution to knowledge and literary
presentation.
Mr. Atsue Tersoo Date
Supervisor
Prof. Adamu, N. Baba-Kutigi Date
Head of Department
Prof. A. O. Musa Date
External Examiner
iv
DEDICATION
This work is dedicated to Almighty Allah for given me opportunity and protection upon me
throughout my period of studies, and to my parents (Alh. Suleiman Makama and Fatima A.
Tukur) for moral and financial supports, also to my sons (Alkhasim (Amir), Safiyyanu (sayyid),
Abubakar (saddik), Hassan ( Abul khairi), as well as Yusuf ), it is also dedicated to Aisha
Aunty, Yaya Ammaru and Malam Ado for they assistance and excellent advice throughout my
period of studies, and to my senior brother Jabir for his constantly prayer toward my staying in
Fudma.
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ACKNOWLEDGEMENT
Firstly, I thank to Almighty Allah for given me opportunity and protection upon me throughout
my period of studies. I thank to my parent for they constantly prayer throughout of my studies. In
addition, I say thank to the entire Zarewa Makama family for they encouragements as well as
good advice throughout my programs.
Also, I thank to my project supervisor Mr. Atsue Tersoo without his time, energy, guidance as
well as sacrifices this project will never be achieved, also I thank to the departmental project
coordinator Dr. Emmanuel Joseph for his wonderful coordinating in this research, may the
Almighty Allah reward them in excess. My thanks go to H.O.D Prof. Adamu N. Baba kutigi,
staff of the Department of Physics Federal University Dutsin-Ma for giving me all the necessary
support and assistance needed from the beginning up to the end of my program. Special to thanks
the entire laboratory technician of Physics Department for they guidance during my experimental
practical. Very good thanks to my colleague student of physics Department, room mite, for they
special advice during my research work, and also I extend my thanks to Sani S. Makama, Uwani
S. Makama, Aisha S. Makama, Ammaru S. Makam, Adamu S. Makama, Lawal S. Makama, Isah
S. Makama, Uwale, as well as Jabir, I sincerely thanks you all for elderly advices,
encouragements, and financial support towards my studies. Also I say thank to A. Bashir lawan
Soron dinki, Bashir mai pillars, Salima, Suwaiba, Ibrahim, Sa’ad, Salisu, Zainab Baba and
Zainab Mama, Aliya, Shuaibu, as well as Baba Aminu (Al-amin) for they constantly prayers.
Finally, I will not forget to extend my special thanks to the entire Zarewa special Group member,
Aljazeera photos chamber, Abdullahi Aliyu, Babajo, Ibrahim aminu iros, Late Gambo Sani,
Sadauki, Baban Yara , khalipha Ahmed for they good advice and prayer, also to those who have
contributed in one way or the other for the success of this program, may Almighty Allah bless
them all in here and hereafter.
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TABLE OF CONTENTS
TITLE PAGE i
DECLARATION ii
CERTIFICATION iii
DEDICATION iv
ACKNOWLEDGEMENT v
TABLE OF CONTENT vi
LIST OF TABLES ix
LIST OF FIGURES x
ABSTRACT xi
CHAPTER ONE : Introduction
1.1 Background of the Study 1
1.2 Aim and Objective 3
1.3 Significant of the Study 4
1.4 Scope and Limitations of the Study 4
CHAPTER TWO: Literature Review
2.1 Review of Basics Concepts 5
2.2Thermal Conductivity (k-value) 5
2.2.1 Measurement of Thermal Conductivity 5
2.2.1.1 Lee’s Charlton’s Disc Method 5
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2.2.1.2 Lee’s Disc Method 6
2.3 Thermal Resistivity (r-value) 8
2.3.1 Measurement of thermal Resistivity 8
2.3.2 Lee’s Disc Method and Charlton Apparatus Method 9
2.4 Thermal Absorptivity (α) 9
2.4.1 Measurement of Thermal Absorptivity 10
2.4.2 Lee’s Disc Method and Charlton Apparatus Method 10
2.5 Thermal Diffusivity (λ) 10
2.5.1 Measurement of Thermal Diffusivity 11
2.5.2 Lee’s Disc Method and Charlton Apparatus Method 11
2.6 Specific Heat Capacity 11
2.7 Density 12
2.8 Heat Transfer 13
2.8.1 Thermal Conduction 13
2.8.2 Thermal Convection 14
2.8.3 Thermal Radiation 14
2.9 Review of Previous Work 14
CHAPTER THREE : Materials and Methods
3.1 Introduction 18
3.2 List of Materials Used 18
3.2.1 Materials and their Uses 19
3.2.2 Ceiling Sample in Building 20
3.2.3 Description of Lee’s Disc Apparatus Machine 21
viii
3.3 Procedure 22
CHAPTER FOUR: Results and Discussion
4.1 Sample Mass and Dimensions 25
4.2 Rate of Heat Lost 26
4.3 Thermal Conductivity 26
4.4 Thermal Resistivity 28
4.5 Density 29
4.6 Thermal Diffusivity 30
4.7 Thermal Absorptivity 32
4.8 Constant Specific heat Capacity 33
4.9 Graph of All Ceiling Sample 35
CHAPTER FIVE: Summary, Conclusion and Recommendation
5.1Summary 37
5.2 Conclusion 37
5.3 Recommendation 39
REFERENCES
ix
LIST OF TABLE
Table Page
4.1 Sample Mass and Dimensions 26
4.2 The Rate of Heat Lost 27
4.3 Thermal Conductivity of all Ceiling Sample 28
4.4 Thermal Resistivity of all Ceiling Sample 27
4.5 Density of all Ceiling Sample 28
4.6 Thermal Diffusivity of all Ceiling Sample 30
4.7 Thermal Absorptivity of all Ceiling Sample 31
4.8 Constant Specific Heat Capacity of the Materials 32
x
LIST OF FIGURES
Figures Page
2.1 Lee-Charlton’s Disc for Measurement of Thermal Conductivity 6
2.2 The lee’s disc machine 7
3.1 dimensions of specimen 19
3.2. Plaster of Paris ceiling sample 20
3.3 Polyvinyl chloride ceiling sample 20
3.4 Asbestos ceiling sample 20
3.5 card board ceiling sample 21
3.6 Diagram of lee’s disc apparatus machine 21
4.1 Comparison of Thermal Conductivity 28
4.2 Comparison of Thermal Resistivity 27
4.3 Density Comparison of all Ceiling Sample 29
4.4 Comparison of thermal diffusivity 30
4.5 comparison of thermal absorptivity 32
xi
ABSTRACT
This work investigates the thermal properties of Polyvinyl Chloride (PVC), Plaster of Paris
(POP), asbestos, and cardboard commonly used as ceiling materials. The steady state method for
Lee’s disc apparatus was employed to determine these thermal properties which include, thermal
conductivity, thermal resistivity, thermal diffusivity, thermal absorptivity and density. The
obtained results of thermal conductivity showed that, POP ceiling has the highest value of
0.1314 while card board has the least value of 0.0851 where as PVC (0.1083 ) and asbestos (0.1068 ) fall in between them. Also the results of thermal conductivity
of this research ranged from (0.0851 0.1314w ) which corresponds to the previous work
of the researchers. Hence all these materials are good insulators. The thermal resistivity of these
ceiling samples showed that, the card board ceiling has highest value of 11.7509 , while
POP has the least value of 7.6103 , the asbestos value (9.3633 ) and PVC value
(9.2336 ) fall in between them. The results of the ceiling samples for thermal diffusivity
showed that PVC ceiling has the highest value of ) while asbestos ceiling
has the least value of 6.0 x ), where the POP value of 1.20 x ) and card
board value of 8.0 ) fall in between them. Also results of thermal absorptivity of
these ceiling materials showed that, the card board ceiling has the highest thermal absorptivity
of 21.319 while PVC has the least thermal absorptivity of 7.573 , where the POP
(17.407 ) and asbestos ( 15.070 ) fall in between them. The density results of these
ceiling materials were showed that, the POP has the highest density value of 979.84 kg/m3
while the P V C has the least density value of 203.59 kg/m3, where the asbestos ( 824.13kg/m
3)
and card board (645.81 kg/m3) densities value fall in between them. The results obtained
showed based on comparison that, PVC and asbestos may be better materials for building
insulation since they have better thermal efficiency. Card board among the samples used was
found to have the least thermal efficiency base on the comparison where as POP falls in between
them. Thus, this research may provide guide for many users of the materials.
1
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Ceiling materials are overhead interior surfaces that can cover the upper limits of the room. They are
not generally considered as structural element but finished surfaces concealing the underside of room
structure or the floor of store above.
In Nigeria, the use of zinc made roofs without ceilings are very common, thus there is intense heat
transfer to the internal environment, which may cause thermal discomfort to the inhabitants (Etuk et
al., 2007). One way to reduce the thermal discomfort is by the use of radiant barrier (i.e. ceiling
board) which reduce the heat flux.
However, the knowledge of thermal properties of different materials is very important in the choice
of the types of materials to be used as a radiant barrier since the heat flow through any building
depends on the thermal properties of the materials use in the building (Etuk et al., 2007).
The study of the thermal properties of materials will help us to know whether materials are suitable
to use as Ceiling materials in our houses, school and industries.
Heat propagated in the interior spaces in buildings through roofs and walls and partly through
Ceiling panels by the process of conduction and radiation (George et al., 2010). This is because the
common materials used as roofing sheets are materials like zinc and aluminum which have high
thermal conductivities (Michael et al, 2012).
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To reduce the intensity of this heat, there is need to use materials of tolerable thermal responses as
ceiling materials in buildings.
Good insulating materials will have high value of thermal resistivity. This implies that, different type
of ceiling materials will have different thermal behaviors.
Insulator is a material or devised used to inhibit or prevent the conduction of heat or electricity (Gesa
et al., 2014). Proper selection of insulating materials is based on their thermal properties which
include: the thermal conductivity, thermal absorptivity, thermal diffusivity, specific heat capacity
(Gesa et al 2014). The primarily function of insulator in buildings are: To conserve energy, to
reduce heat loss or heat gain, to maintain a temperature condition, to maintain the effective
operation of equipment or chemical reaction, to assist in maintaining product at constant
temperature, to prevent condensation, to create comfortable environmental condition and protect
personnel. Insulation reduces heat transfer through the envelope in building. Whenever there is a
temperature difference, heat flows naturally from a warmer space to a cooler space. To maintain
comfort in winter (the coldest season of the year), the heat lost must be replaced by the heating
system; and in summer (the warmest season of the year), the heat gained must be removed by the
cooling system. Therefore, it makes sense to study the thermal properties of insulator in order to
reduce gains or loss of energy in buildings and to increase comfortable condition in houses, schools
and industries.
Novo et al, (2010) justified that, the thermal insulation is provided by embedding insulation
materials at least on the roof areas and the vertical walls of the systems. Insulating materials are
3
usually made in various types with different design which lead them to categorize in to good and bad
insulators on their properties.
In this work, emphasis is laid on the study and comparison of thermal properties of some selected
materials which include PVC (polyvinylchloride), POP (plaster of Paris), asbestos and cardboard
used as ceilings in buildings. Depending on how large or small the value of their thermal properties,
a particular ceiling materials may be more efficient in terms of thermal insulation than another
(George et al., 2010).
Observation showed that in this present competitive world, people that are economically favored
usually go for the most costly ceiling materials without any preference to the thermal insulation
efficiency of such materials. It is based on this observation that this work is designed to investigate
and compare the thermal properties of the most frequently used ceiling materials for efficient thermal
insulation. This will determine the suitability of one ceiling material to another in order to have
comfortable thermal condition in buildings.
1.2 AIM AND OBJECTIVE OF THE PROJECT
The aim of this project is, to measure the thermal properties of some material used as ceiling in
building and to compare the values of each of them for thermal efficiency. These materials include
PVC, POP, and ASBESTOS, CARDBOARD.
The objective of the project include,
i. To measure their thermal absorptivity
ii. To measure their thermal diffusivities.
4
iii. To measure their thermal conductivity and determine their thermal resistivity.
iv. To calculate the density of each four sample.
1.3 SIGNIFICANT OF THE STUDY
Achieving the set objectives of this work will enable us to have adequate knowledge of materials
which are more suitable for thermal insulation.
The results may be sufficient to tell us the efficiency of these materials. Thus, it will be important to
create awareness to the general public, on which of the materials to go for, while constructing
buildings in order to get maximum thermal comfort.
1.4 SCOPE AND LIMITATIONS OF THE STUDY
The research is focused on the study of thermal properties of some materials used as ceilings in
buildings. The materials in consideration include P V C, POP, asbestos and cardboard. The thermal
properties of interest include thermal conductivity, thermal resistivity, thermal radiation, thermal
absorptivity, thermal diffusivity, specific heat capacity and density.
Due to time and financial constraints, the research will not go beyond this scope.
5
CHAPTER TWO
LITERATURE REVIEW
2.1 REVIEW OF BASICS CONCEPTS
In this chapter a detailed review of thermo physical properties of ceiling materials in building is
considered. Also, a review of related literature is considered in detailed.
2.2 THERMAL CONDUCTIVITY (k-value)
According to Mohammed et al., (2010), the thermal conductivity , is the property of materials that
indicates its ability to conduct heat. Conduction will take place if there exists a temperature gradient
in a solid (or stationary fluid) medium. Energy is transferred from more energetic to less energetic
molecules when neighboring molecules collide. Conductive heat flow occurs in direction of the
decreasing temperature because higher temperature is associated with higher molecular energy.
Thermal conductivity is regarded as the most important characteristics of a thermal insulation. The
lower the thermal conductivity value, the lower the overall heat transfer. The thermal conductivity of
insulating materials has been found to vary with density and temperature.
2.2.1 Measurement of Thermal Conductivity
Generally speaking, there are number of procedure in measure thermal conductivity, each of them
being suitable for a limited range of materials, depending on the thermal properties and the medium
temperature. The most commonly used methods are Lee- Charlton’s disc method and Lee’s disc
method, for good and poor conductors of heat, respectively.
2.2.1.1 Lee’s Charlton’s Disc Method.
6
Gesa et al., (2014) carried out experiment on measuring the thermal conductivity of insulator
materials (P O P, Plywood, Isorel ) in Makurdi by using lee’s Charlton apparatus method. The results
obtained from their experimental method, showed that, the lee’s Charlton apparatus method can be
used in measuring the thermal conductivity of ceiling insulator materials.
Emmanuel et al., (2016) carried out experiment on measuring the thermal conductivity of insulator
materials (P V C) in Calabar by using lee’s Charlton apparatus method. The result obtained from
their method, showed that, the lee’s Charlton apparatus method can be used in measuring the thermal
conductivity of ceiling insulator materials in building.
Alam et al., (2012) carried out experiment on measuring the thermal conductivity of insulator
materials by using lee’s Charlton machine apparatus. The result obtained from their experimental
method, showed that, the experiment method of lee’s Charlton machine apparatus can be used in
measuring the thermal conductivity of insulator materials.
The diagram below is the lee’s Charlton disc apparatus with two thermometer, sample disc and two
arrow showing steam in and steam out respectively (Gesa et al., 2014).
Fig: 2.1 Lee-Charlton’s Disc for Measurement of Thermal Conductivity.
7
2.2.1.2 Lee’s Disc Method.
Alausa et al., (2011) carried out experiment on measuring the thermal conductivity of some insulator
materials by using lee’s disc apparatus method. The result obtained from their experimental method,
shows that, the lee’s disc apparatus method can be used in measuring thermal conductivity of
insulator materials.
George et al., (2010) carried out experiment on measuring the thermal conductivity of some insulator
materials by using lee’s disc apparatus method. The result obtained from their method was find out
successfully, which shows that, the lee’s disc apparatus method can be used in measuring the thermal
conductivity insulator materials.
Ramesh et al., (2014) carried out experiment on measuring the thermal conductivity of some
insulator materials by using lee’s disc apparatus method. The result obtained from their method,
shows that, the lee’s disc apparatus can be used in measuring the thermal conductivity of ceiling
insulator materials.
The diagram below is the lee’s disc apparatus with two thermometer, one sample materials and two
arrows showing the steam in and steam out of the heater (H).
8
Fig: 2.2 The lee’s disc machine.
Gesa et al.,(2014) the Fourier’s law heat transfer below can be used in calculating the thermal
conductivity, since, at steady state, the heat conducted through the sample will be equal to heat lost
per second from the exposed portion of the metallic disc.
⁄
[
]
Where K = thermal conductivity of the sample, C = specific heat capacity of the sample, X =
thickness of the sample,
is the Cooling rate of the steel disc at , A = Area of the sample in
contact with the steel disc, equal to temperature difference across the samples thickness.
Under steady state conditions and when the heat is transfer is dependent only on the temperature
gradient. The thermal conductivity of ceiling insulators materials is measured in ⁄ .
2.3 THERMAL RESISTIVITY (R-VALUE)
9
Thermal resistivity of a materials is the reciprocal of thermal conductivity of the materials, it may be
define as the time required for one unit of heat to pass through unit area of a materials of unit
thickness when unit temperature exists between opposite faces.
Michels et al., (2008) thermal resistivity of the materials is the reciprocal of thermal conductivity of
the materials. It’s measured in -1mk
Where R= is the resistivity, = thermal conductivity. The value of each thermal resistivity of ceiling
materials in buildings can be found or measured as we have the reading value of thermal
conductivity.
2.3.1 Measurement of thermal Resistivity
It was observed that, the thermal conductivity of ceiling insulator materials was regard as the best
thermo physical properties of insulator materials which give the opportunity to measure the
remaining thermo- physical properties of insulator materials.
According to George et al., (2010) and Gesa et al., (2014), the reciprocal of thermal conductivity is
the thermal resistivity.
Where R= is the resistivity, k= thermal conductivity. Similarly the above statement was also justified
according to the (Michael et al., 2012).
2.3.2 Lee’s Disc Method and Charlton Apparatus Method.
10
Both Lee’s disc method and Charlton method can be used in measuring thermal resistivity of ceiling
insulator materials in building. The reciprocal thermal conductivity value of ceiling insulator
materials give the thermal resistivity value of any ceiling insulator materials. (Gesa et al., 2014) and
(Michael et al., 2012).
2.4 THERMAL ABSORPTIVITY (α)
George et al., (2010), the thermal absorptivity can be define as the ability of ceiling materials to
absorb energy.
According to the Kirchhoff’s Law, which states that the absorptivity of a body has to be equal its
emissivity at every wavelength. The classical argument begins with considering a body placed in a
blackbody cavity at temperature T. Energy balance for the body requires that it emits as much
energy as it absorbs, and thus doesn’t heat up or cool down. Therefore, we can calculate the thermal
absorptivity of the materials by using relation below.
√
Where = thermal absorptivity, = 2π / period, = thermal diffusivity. Where the measurement
unit is m-1
2.4.1 Measurement of Thermal Absorptivity.
It was justified that, the Measurement of thermal absorptivity can be find out as we have the value of
thermal diffusivity of the materials (Gesa et al., 2014) and (Michael et al.,2012).
11
2.4.2 Lee’s Disc Method and Charlton Apparatus Method.
It was observed that, the thermal diffusivity of the materials was among the thermal properties of
insulator ceiling materials, which lead us in calculating the thermal absorptivity of the ceiling
materials. Therefore, both Lee’s disc method and Charlton method can be used in measuring the
thermal absorptivity of insulator materials since there is relationship between the thermal
conductivity and thermal diffusivity of any insulator materials.
2.5 THERMAL DIFFUSIVITY (λ)
Michael et al., (2012) thermal diffusivity is a measure of the ability of substance or energy to allow
heat radiation pass by diffusion. Where the unit of measurement is m2/s.
According to Gesa et al., (2014) Thermal diffusivity measures the ability of a material to transmit a
thermal disturbance. It indicates how quickly a material’s temperature will change. Thermal
diffusivity therefore increases with the ability of a body to conduct heat and decreases with the
amount of heat needed to change the temperature of the body. Thermal diffusivity can be expressed
below.
Where = thermal diffusivity, = thermal absorptivity, = is the density, = specific heat of
materials, the diffusivity of each ceilings samples in buildings can be obtained since we can be able
to measure the value of each thermal conductivity of four samples that we have were the values of
density and specific heat capacity can be obtained using relation below, (George et al., 2010).
2.5.1 Measurement of Thermal Diffusivity.
12
Michael et al.,(2012) The measurement of the thermal conductivity , density and specific heat
capacity , of any materials enable the determination of the value of thermal diffusivity .
Therefore, thermal diffusivity Ceiling insulator materials can be measured using relation in of
the above.
Emmanuel et al., (2016) and Gesa et al., (2014) justified the above statement.
2.5.2 Lee’s Disc Method and Charlton Apparatus Method.
Both Lee’s disc method and Charlton method can be used in measuring thermal diffusivity of ceiling
insulator materials in building. Since there is a relation between thermal diffusivity and thermal
conductivity (Michael et al., 2012).
2.6 SPECIFIC HEAT CAPACITY
We know that when heat energy is absorbed by a substance, its temperature increases. If the same
quantity of heat is given to equal masses of different substances, it is observed that the rise in
temperature for each substance is different. This is due to the fact that different substances have
different heat capacities. So heat capacity of a substance is the quantity of the heat required to raise
the temperature of the whole substance by one degree. If the mass of the substance is unity then the
heat capacity is called Specific heat capacity or the specific heat.
According to Raymond (1989), every substance has a unique value for the amount of heat required
to change the temperature of 1 kg of it by c and this number is referred to as the specific heat of
the substance. Suppose that Q unit of heat are added to m kg of a substance, thereby changing its
temperature by . The specific heat C of the substance is can be expressed below.
13
Where Q is quantity of heat absorbed by a body, m is mass of the substance, is rise in
temperature, C is Specific heat capacity of a substance it depends on the nature of the material of the
substance. Where the unit is
2.7 DENSITY
Density is the dry mass per unit volume of a substance under absolute compact conditions. It is
expressed as
Where is the density (g/cm3); m is the mass under dry conditions (g), v is the volume under
absolute compact conditions cm3.
The volume under absolute compact conditions refers to the solid volume without the volume of
inner pores. Except steel, glass, asphalt and a few other materials, most materials contain some pores
in natural state. In the measurement of the density of a porous materials, the materials is grinded into
powder at first, the powder is dried to fixed mass, and then the solid volume is measured by Lee's
density bottle, finally the density of each samples of this research can be calculated by the above
formula in equation (2.6).
2.8 HEAT TRANSFER
Heat may be transferred in three mechanisms: conduction, convection and radiation. Thermal
conduction is the molecular transport of heat under the effect of a temperature gradient, Convection
mechanism of heat occurs in liquids and gases, whereby flow processes transfer heat. Free
14
convection is flow caused by differences in density as a result of temperature differences. Forced
convection is flow caused by external influences (wind, ventilators, etc.). Thermal radiation
mechanism occurs when thermal energy is emitted similar to light radiation (TIASA 2001).
Heat transfers through insulation material occur by means of conduction, while heat loss to or heat
gain from atmosphere occurs by means of convection and radiation, heat passes through solid
materials by means of conduction and the rate at which this occurs depends on the thermal
conductivity (expressed in W/mK) of the materials (TIASA 2001).
The knowledge of heat transfer is plays an important role in the study of thermal properties of some
selected materials use as ceiling in buildings.
The heat transfer depend on thermal conduction, thermal convection, and thermal radiation.
2.8.1 THERMAL CONDUCTION: The thermal conduction is the process by which heat passes
along a material from molecule to molecule, the heated particles remained in position (Ndupu et al.,
2000).This happens with negligible movement of the molecules in the body, because the heat is
transferred from one molecule to another in contact with it. Heat can be conducted through solids,
liquids and gases. Some materials conduct more rapidly than others. Therefore, it’s important to have
the basic understanding about conduction since some part of the ceilings materials are always in
contact with other building materials.
2.8.2 THERMAL CONVECTION: Thermal convection is the transfer of heat from one part of a
fluid (gas or liquid) to another part at a lower temperature by mixing of fluid particles. Heat transfer
by convection takes place at the surfaces of walls, floors and roofs. Because of the temperature
difference between the fluid and the contact surface, this results in heat exchange between the fluid
15
and the surface and is known as free convection. However, if the motion of the fluid is due to
external forces (such as wind), it is known as forced convection,
Ndupu et al., (2000) defined convection as the process by which heat energy is transferred in liquid
or gas by actual movement of heated fluid.
2.8.3 THERMAL RADIATION: Thermal radiation is the heat transfer from a body by virtue of its
temperature; it increases as temperature of the body increases. It does not require any material
medium for propagation (Ndupu et al., 2011).
2.9 REVIEW OF PREVIOUS WORK
Recent developments are focused on producing insulation materials with good thermal efficiency,
research on thermal properties of ceiling materials in buildings is already been done from many
scholars and good results were also obtained successfully. Therefore, we will not be exceptional in
this very good research. Meaning that, we are going to review in such a case, but this research is only
focused on thermal properties of four sample used as ceilings in buildings (i.e. P V C, POP, asbestos,
cardboard) in order to compare their thermal efficiency of each of them.
George et al., (2010) carried out a research on comparison of thermal properties of some selected
materials used as ceiling in building design at Department of science and technology, Akwa Ibom
State Polytechnic, Ikot Asurua, Akwa Ibom State Nigeria. The research was carried out using five
samples of ceiling materials i.e. P V C, POP, cardboard, asbestos, suspended. During their research
the thermal conductivity, thermal absorptivity, thermal diffusivity, thermal resistivity, specific heat
capacity and density were determine for each sample. The result showed that, P V C and card board
have higher thermal absorptivity’s value, where the POP, asbestos and suspended have lower thermal
16
absorptivity’s value. Based on the molecular point of view of thermal absorptivity, POP, asbestos
and suspended are best materials with high thermal insulation efficiency.
In addition, mathematical calculation has also applied for their research. The results also showed
that, the substances with lower thermal absorptivity and higher thermal diffusivity are very good
insulation materials while substances with higher thermal absorptivity and lower thermal diffusivity
are poor insulating materials (George et al., 2010).
Micheal et al.,(2012) also conducted his research on comparison of thermal properties of Asbestos
and PVC ceilings sheet according to their thermal conductivity, (TC), thermal resistivity (TR),
thermal diffusivity, thermal absorptivity, and specific heat capacity (SHC). They treated the samples
under investigation as an ideal one dimensional heat transfer problems. The results showed that, both
PVC and asbestos ceiling sheet has low density, low thermal conductivity and high thermal
resistivity which compared favorably with those of other good thermal insulators in building design.
Emmanuel et al., (2016) carried out a research to investigation of the thermal conductivity of
polyvinyl chloride (P V C) ceiling material produced in Export Processing zone (EPZ) in Calabar,
For application tropical climate zones, according to their research thermal properties of PVC
produced in the Export Processing zone (EPZ) in Calabar, Nigeria with the view of establishing it
suitability as an insulating ceiling material for building design in tropical region has been investigate.
Results showed that, thermal conductivity was 0.17W -1k
-1, thermal resistivity 5.88W
-1mk and
thermal diffusivity of 7.8x10-6
m2/. This makes it suitable as ceiling material for application in
tropical climate zones because the sample used falls within the range of good insulating materials,
which is range from 0.023 to 2.9 Wm-1
k-1
. According to Twidell (1989) and Weir (1990) as cited in
17
Emmanuel et al., (2016), materials with thermal conductivity range between
are good insulating materials.
Gesa et al.,(2014) at Department of physics, College of science / University of agriculture, Nigeria.
Conducted their research on investigation of the thermal insulation properties of selected ceiling
materials used in Makurdi Metropolis (Benue State, Nigeria). In their research, the thermal insulation
properties of three selected materials namely: Plaster of Paris (P O P), Plywood and Isorel
(Masonite) used as ceiling boards in Makurdi, Benue state Nigeria, have been investigated. The
steady state method using Lee-Charton’s apparatus was adopted to analyze the thermal conductivities
of the chosen materials. The results showed that, POP exhibits the best insulation property followed
by plywood then Isorel ceiling board with thermal conductivities of 0.1185 w/m k, 0.1768 w/m k and
0.4498 w/m k respectively. Their corresponding thermal resistivities are 8.4388mk/w, 5.6561mk/w
and 2.2232mk/w.
Alausa et al., (2011) carried out a research on the thermal property of Rattan palms (Calamus
deërratus), Raffia palms (Raphia hookeri) and synthetic board (asbestos) in building design in
Southwestern Nigeria. The Lees’ disc apparatus were used in finding the result on their experiment.
The results showed that, Rattan palms sheet have the lower thermal conductivity (k = 0.046 Wm-1
K-
1) and a higher resistivity (R 21.930 W
-1mk), While both palms showed lower thermal conductivity
(k = 0.046 to 0.056 Wm-1
k-1
) and higher resistivity (R = 17.73 to 21.930 W-1
mk) than asbestos sheet
(k = 0.084 Wm-1
K-1
, R = 11.919 W-1
mk). The results also indicated that, the Rattan palms have
higher resistivity than many other woods.
18
In addition, Alausa also compared the data values published by the previous researchers (Agarwal,
1967; Akpabio et al., 2001; Etuk et al., 2005; Twidell and Weir, 1990) for other wood-based
materials used for heat insulation. The range of thermal conductivity (k) values (0.04 - 0.08 Wm-1
K-
1) determined in this work were far lower than the range of values (0.05 - 0.32 Wm
-1 k
-1) published
for other commonly used materials for heat resistance (Etuk et al., 2005). However, Raffia and pine
wood had similar conductivity, k-values of the three materials tested in this work, only the asbestos
resistivity R value was within the range of values (0.74 - 16.13W-1
mk), while the Rattan and Raffia
values were well above the published range for commonly wood-based insulating materials used for
buildings. Therefore, with respect to the reviews above, we are also going to justified the thermal
properties of some materials use as ceiling in buildings and compare their values of them and fixed
the one with very good thermal efficiency and to make people aware with suitability of it for
generating the constant thermal comfort in buildings but here the research covered only 4 samples of
ceilings materials used in buildings.
19
CHAPTER THREE
MATERIALS AND METHODS
3. 1 INTRODUCTION
This chapter presents the materials and methods used in carrying out this research. A detailed
description of the materials and their functions is presented as well as step by step description of
methods for the research.
3.2 List of Materials used: the materials used in measuring the thermal conductivity of the four
samples ceiling materials are:
(a) Lee’s disc apparatus
(b) The experimental specimen in the form of a disc( ceiling sample)
(c) Three metal disc approximately 42mm x 12mm thick, each drilled radially to take a
thermometer.
(d) Two thermometers of 1500
C range
(e) Stop watch
(f) Weighing balance
(g) Micrometer screw gauge
(h) Vanier caliper
(i) An electrical heated disc of (6 to 12 volt) with wire lead out to 4mm sockets
(j) Special lamp stand
(k) A wooden frame for clamping the disc together.
20
3.2.1 Materials and their uses
i. Lee’s disc apparatus: this apparatus is used for measuring the thermal conductivity of bad
conducting material like ceiling and other insulators.
ii. The experimental specimen in the form of a disc (ceiling sample).
Four samples of materials frequently used as ceiling materials in buildings which include PVC, POP,
cardboard and Asbestos ceiling. The composite samples have been prepared by using hand-lay-up
technique to measure the thermal conductivity (using Lee’s apparatus). The diagram below is the
description of sample shape with dimension of 110mm diameter and thickness of 5mm
Fig: 3.1 dimensions of specimen.
iii. Three metal disc approximately 42mm x 12mm thick, each drilled radially to take a
thermometer, and are used in measuring the steady temperature of the metallic dish.
iv. The thermometer: is an instrument used for measuring and indicating temperature,
typically consisting of a graduated glass tube containing mercury or alcohol which
expands when heated.
v. Stop watch: is used for time taken during the experiment.
21
vi. Digital electronic weighing balance: the digital electronic weighing balance is used for
measuring the mass of the sample.
vii. Vanier caliper: the Vanier caliper is used for measuring the diameter of the specimen
samples.
viii. Micrometer screw gauge: is used for measuring the thickness of the materials sample.
ix. An electrical heated disc of (6 to 12 volt) with wire lead out to 4mm sockets: serve as
power supply source to the lee’s disc apparatus.
x. A wooden frame for clamping the disc together: is used for clamping.
3.2.2 CEILING SAMPLE IN BUILDING
Fig. 3.2. Plaster of Paris ceiling sample.
Fig. 3.3 Polyvinyl chloride ceiling sample.
22
Fig. 3.4 Asbestos ceiling sample.
Fig. 3.5 card board ceiling sample.
3.2.3 DESCRIPTION OF LEE’S DISC APPARATUS MACHINE.
Lee’s disc apparatus: this apparatus is used for measuring the thermal conductivity of bad
conducting material like ceiling materials. The machine has three metal disc attached to
it, each of them drilled radically to take a thermometer. Space of samples is also made
available between the two drilled metal disc for inserting insulator material (glass or
ceiling). The heater disc is attached with power supply for supplying the lower voltage.
23
Fig. 3.6 Diagram of lee’s disc apparatus machine.
3.3 PROCEDURE
The four sample materials frequently used as ceiling materials in buildings which include: P V C,
POP, asbestos and cardboard were collected from the building materials shop at Dutsin-ma market
and Sabon gari Kano market. The samples were labeled and shaped to take the dimension of the lee’s
disc apparatus. Diameter of each sample was measured using vernier caliper and the thickness
measured using micrometer screw gauge. The mass of each sample was measured using weighing
balance. The densities was found out by making use of mass per unit volume of each sample. The
drilled metal discs i.e. A, B and C heater disc and sample disc of lees disc apparatus were assembled
together, the fan and windows of the laboratory were completely closed in order to excess lost of
heat. The two thermometers were inserted in to the two drilled metal disc on the either side of sample
disc, the spaces around the thermometer bulbs were filled with oil in order to maximize the thermal
24
contact. The heater disc was connected to a low voltage power supply where the voltage was
adjusted until a steady state was reached. The temperature reading of were taking by using
two thermometers respectively, the rate of loss of heat of the end disc C found by heating up to 100C
above the steady state of these temperatures below. For card board ceiling we have
, asbestos, POP,
and for PVC, . The
temperature were recorded earlier for each sample. The thermal conductivity K, density
thermal diffusivity, , absorptivity , and resistivity were measured for each sample using the
equations (3.1),(3.2), (3.3), (3.4)and (3.5) respectively, shown below.
Thus,
Where from equation (3.1) and (3.2), H is the rate of heat flow, m is the mass of the disc, c is the
specific heat capacity of metal disc, x is the thickness of the sample materials, A is the cross-
sectional area of the sample, is the difference in the steady state temperature and
is the
gradient from the cooling curve.
25
√
Where from equation m is the mass of the sample under dry conditions
(g), v is the volume of the sample under absolute compact conditions in cm3, = 2π / period T (T is
the total hours in a day).
26
CHAPTER FOUR
RESULT AND DISCUSSION
In this chapter, the results obtained from experiments are presented and discussed in detailed. Since
the investigation was done for different samples, the results are compared to find the best ceiling
material for building insulation purposes.
4.1 SAMPLE MASS AND DIMENSIONS
The mass of each sample was measured with a weighing balance and their dimensions also measured
with the aid of micrometer screw gauge and the vernier calipers. The results are presented in table
4.1 below.
TABLE 4.1 Sample Mass and Dimensions
SAMPLE MASS(Kg) THICKNESS(m) DIAMETER(m)
PVC
POP
CARD
BOARD
ASBESTOS
27
The results presented in the above table are useful in the deduction of other relevant parameters
needed in this research work which will be presented later in this chapter. For each sample at room
temperature, ( ), the temperature variation with corresponding time interval is taken and the
results are presented in page 34.
28
4.2 RATE OF HEAT LOST
A graph of temperature θ, was plotted against time and the slope was obtained which represents the
rate of heat lost presented in table 4.2 below.
Table 4.2 The Rate of Heat Lost
SAMPLE TYPE Rate of heat lost
PVC 0.015000 0.000004
POP 0.018000 0.000003
CARD BOARD 0.017000 0.000003
ASBESTOS 0.014000 0.000003
The results presented above indicate that, Asbestos has the least rate of heat lost while POP has the
highest rate of heat lost. The results of table 4.1 and 4.2 are used to obtain the thermal conductivities
of samples which are presented in next section.
4.3 THERMAL CONDUCTIVITY
The thermal conductivity of these samples were computed from the results of the mass presented in
table 4.1 and the rate of heat lost presented in table 4.2.
Equation 3.2 was invoked for this computation and the thermal conductivity of each sample is
presented below in table 4.3.
29
Table 4.3 Thermal Conductivity of all Ceiling Sample
SAMPLE TYPE THERMAL CONDUCTIVITY
)
PVC 0.108
POP 0.131
CARD BOARD 0.085
ASBESTOS 0.106
Fig. 4.1 Comparison of Thermal Conductivity
From table 4.3, the results of thermal conductivity of all ceiling sample materials showed that, the
POP ceiling has highest value of 0.1314 , while the card board has the least value of
0.0851 , where the P V C ( 0.1083 ) and asbestos (0.1068 ) fall in between them.
PVC POP CARD BOAD ASBESTOS
CONDUCTIVITY 0.1083 0.1314 0.0851 0.1068
0.1083
0.1314
0.0851
0.1068
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
THER
MA
L C
ON
DU
CTI
VIT
Y
CEILING SAMPLE
THERMAL CONDUCTIVITY OF ALL CEILING SAMPLE
CONDUCTIVITY
30
The thermal conductivity of all ceiling sample materials of this research corresponded to the results
of previous researchers, which were showed that, all the materials sample in this research are good
insulating materials since their thermal conductivities fall within the range conductivities of
construction and heat-insulating materials ( ) According to Twidell and
Mahhrer, (1982) and Weir 1990) as cited in Emmanuel et al., (2016).
4.4 THERMAL RESISTIVITY
The results obtained from the successful calculated thermal resistivity of all ceiling sample were
showed in table 4.4.
Also the comparison of these thermal parameters were showed in figure 4.2
Table 4.4 Thermal Resistivity of all Ceiling Sample.
SAMPLE TYPE THERMAL RESISTIVITY
PVC 9.2
POP 7.6
CARD BOARD 11.7
ASBESTOS 9.3
31
Fig. 4.2. Comparison of Thermal Resistivity
From table 4.4 the results of thermal resistivity of all ceiling sample showed that, the thermal
resistivity of card board ceiling has highest value of 11.7509 while POP has the least value of
7.6103 , the asbestos value (9.3633 ) and p v c value( 9.2336 ) fall in between
them. Thermal resistivity which was regarded as the reciprocal of thermal conductivity of ceiling
materials is very important in this research because it lead us to classify the ceiling insulators
materials base on thermal efficiency.
In order words a good insulation material will have high resistivity-value for thickness other than 1m
(Gesa et al., 2014).
4.5 DENSITY
The results obtained from the successful calculated density of each ceiling materials were shown in
table 4.5. Also the comparison of these densities is shown in figure 4.3 below.
Table 4.5: Density of all Ceiling Samples.
PVC POPCARD
BOARDASBESTOS
RESISTIVITY 9.2336 7.6103 11.7509 9.3633
9.2336 7.6103
11.7509
9.3633
0
2
4
6
8
10
12
14
THER
MA
L R
ESIS
TIV
ITY
SAMPLE CEILING
THERMAL RESISTIVITY OF ALL CEILING SAMPLE
RESISTIVITY
32
SAMPLE TYPE DENSITY
)
PVC 203.590
POP 979.840
CARD BOARD 645.810
ASBESTOS 824.130
Fig 4.3 Density Comparison of all Ceiling Samples.
From table 4.5, the results showed that POP has the highest density value of 979.84 kg/m3 while the
PVC has the least density value of 203.59 kg/m3, where the asbestos (824.13kg/m
3) and card board
PVC POP CARD BOARD ASBESTOS
Series1 203.59 979.84 645.81 824.13
203.59
979.84
645.81
824.13
0
200
400
600
800
1000
1200
DEN
SITY
CEILING
DENSITY OF ALL CEILING SAMPLES
33
(645.81 kg/m3) densities value fall in between them. The density of ceiling materials which was
regarded as the dry mass per unit volume of a ceiling materials under the absolute compact
conditions in cm3 is very important in this research because it lead us to calculate the result of
another thermal parameter (i.e. thermal diffusivity) such that we can be able to classify these ceiling
materials base on thermal efficiency.
4.6 THERMAL DIFFUSIVITY
The results obtained from the successful calculated thermal diffusivity of all ceiling sample materials
were showed in table 4.6. Also the comparison of these thermal parameters is shown in figure 4.4
below.
34
Table 4.6 Thermal Diffusivity of all Ceiling Sample
SAMPLE TYPE THERMAL
DUFFUSIVITY
)
PVC
POP
CARD BOARD
ASBESTOS
Fig. 4.4 Comparison of thermal diffusivity
From table 4.6 the results showed that, the thermal diffusivity of PVC has the highest value
of ) x while asbestos has the least value of 0.60 ) x , where the POP with
PVC POP CARD BOARD ASBESTOS
DIFFUSIVITY 6.34 1.24 0.8 0.6
6.34
1.24 0.8 0.6
0
1
2
3
4
5
6
7
THER
MA
L D
IFFU
SIV
ITY
CEILING SAMPLE
THERMAL DIFFUSIVITY OF ALL CEILING SAMPLE
DIFFUSIVITY
35
value of 1.20 ) x and card board with value of 0.80 ) x fall in between them.
Thermal diffusivity measures the ability of a material to transmit a thermal disturbance; it indicates
how quickly a materials temperature will change.
Thermal diffusivity therefore increases with the ability of a body to conduct heat and decreases with
the amount of heat needed to change the temperature of a body (Gesa et al., 2014). Hence the
thermal diffusivity parameter is very vital and important in this research because it enable us to
calculate the thermal absorptivity and to give us opportunity classify these ceiling insulators
materials base on thermal efficiency.
4.7 THERMAL ABSORPTIVITY
The results obtained from the successful calculated thermal absorptivity of all ceiling sample were
showed in table 4.7. Also the comparison of these thermal parameters is shown in figure 4.5 below.
Table 4.7. Thermal Absorptivity of all Ceiling Sample
SAMPLE TYPE THERMAL ABSORTIVITY
PVC 7.573 2.0
POP 17.407
CARD BOARD 21.319
ASBESTOS 15.070
36
Fig. 4.5 comparison of thermal absorptivity
From table 4.7 the results showed that, the card board ceiling has the highest thermal absorptivity of
21.319 while P V C has the least thermal absorptivity of 7.573 , where the POP
(17.407 ) and asbestos ( 15.070 ) fall in between them.
Thermal absorptivity according to George et al. (2010) is the ability of materials to absorb heat
disturbance into the building. Therefore, the thermal absorptivity value is very important in this
research because it enable us to classify these ceiling materials base on thermal efficiency.
4.8 CONSTANT SPECIFIC HEAT CAPACITY
Table 4.8: Constant Specific Heat Capacity of the Materials.
MATERIAL TYPE SPECIFIC HEAT CAPACITY ⁄
BRASS 375
PVC POP CARD BOARD ASBESTOS
ABSORPTIVITY 7.573 17.407 21.319 15.07
7.573
17.407
21.319
15.07
0
5
10
15
20
25TH
ERM
AL
AB
SOR
PTI
VIT
Y
CEILING SAMPLE
THERMAL ABSORPTIVITY OF ALL CEILING SAMPLE
37
PVC 841
ASBESTOS 816
CARD BOARD(WOOD) (1300 – 2400)
POP 1090
The table above are the constant specific heat capacity of some materials that were used in this
research.
In general, by considering the absorptivity thermal parameter we can says that, the P V C and
asbestos have the lower absorptivity value and then followed by POP, where the card board has the
highest value of thermal absorptivity.
According to George et al., (2010) the classification of good ceiling insulating materials it can be
based on the thermal absorptivity. Therefore, by considering the two thermal parameters in this
research we can equally say that, the lower the thermal absorptivity value irrespective of lower or
higher of thermal diffusivity portray a good thermal insulation efficiency of ceiling materials in
building.
38
4.9 GRAPH OF ALL CEILING SAMPLE
GRAPH OF TEMPERATURE AGAINS PVC CEILING
GRAPH OF TEMPERATURE AGAINS POP CEILING
54 52
50 49 47 46 45 44 43
0
10
20
30
40
50
60
0 2 4 6 8 10 12 14 16 18 20
TEM
PER
ATU
RE
IN D
EGR
EE
TIME IN MINUTES
TEMP OF PVC
Linear (TEMP OF PVC)
76 72
69 67 64 62
59 57 56 54 53 52 50 49 48 47
0
10
20
30
40
50
60
70
80
0 5 10 15 20 25 30 35
TEM
PER
ATU
RE
IN D
EGR
EE
TIME IN MINUTE
TEMP OF POP
Linear (TEMP OF POP)
39
GRAPH OF TEMPERATURE AGAINS CARD BOARD CEILING
GRAPH OF TEMPERATURE AGAINS ASBESTOS CEILING
81 77
73 70 68
65 63 60 58 56 54 53 52 50 49 48 48 47 46 45 45 44 44
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50
TEM
PER
ATU
RE
IN D
EGR
EE
TIME IN MINUTES
TEMP OF CARD BOARD
Linear (TEMP OF CARDBOARD)
72 68
64 62 60 58 56 54 52 51 50 48 47 46 45 45 44 43 43 42 42 41 41 41 40
0
10
20
30
40
50
60
70
80
0 10 20 30 40 50 60
TEM
PER
ATU
RE
IN D
EGR
EE
TIME IN MINUTES
TEMP OF ASBESTOS CEILING
Linear (TEMP OF ASBESTOSCEILING)
40
CHAPTER FIVE
SUMMARY, CONCLUSION AND RECOMMENDATION
This chapter presents the summary and conclusion of this research. A detailed recommendation is
given at the end of this chapter.
5.1 SUMMARY
This research was focused on measuring the thermal property of some selected materials used as
ceiling in building. Some of these thermal parameters include thermal conductivity, resistivity,
diffusivity, absorptivity. Generally speaking, there are numbers of procedure in measure thermal
conductivity, each of them being suitable for limited range of materials, depending on the thermal
properties and the medium temperature. The most commonly used methods are Lee- Charlton’s disc
method and Lee’s disc method, for good and poor conductors of heat respectively, but this research
was limited only to the use of lee’s disc apparatus method.
Having use the instruments like lee’s disc machine apparatus, digital electronic weighing balance,
micrometer screw gauge, Vanier caliper, stop watch and thermometers respectively, The results of
thermal conductivity of all ceiling samples materials showed that, the POP ceiling has highest value
of 0.1314 while the card board has the least value of 0.0851 , where the P V C
(0.1083 ) and asbestos (0.1068 ) fall in between them. Also the results of thermal
resistivity of all ceiling samples showed that, the thermal resistivity of card board ceiling has highest
41
value of 11.7509 while POP has the least value of 7.6103 , where the asbestos value
(9.3633 ) and P V C value (9.2336 )fall in between them.
Theoretically, a substance with a highest thermal conductivity value is a bad insulator while one with
a least thermal conductivity value is a good insulator. In order words a good insulator materials will
have high resistivity value for thickness other than 1m.
The results of thermal diffusivity of P V C were showed that, the P V C has the highest value
of ) x while asbestos has the least value of 0.60 ) x , the pop with value
of 1.20 ) x and card board with value of 0.80 ) x fall in between them. Also
results of thermal absorptivity of these ceiling materials showed that, the card board ceiling has the
highest thermal absorptivity of 21.319 while P V C has the least thermal absorptivity of
7.573 , where the POP (17.407 ) and asbestos (15.070 ) fall in between them.
5.2 CONCLUSION
In conclusion, thermal conductivity of four ceiling samples under this investigation were ranged
from ( ).The results obtained corresponded to the results of previous
researchers, which showed that, all the materials samples in this research are good insulating
materials since their thermal conductivities fall within the range conductivities of construction and
heat-insulating materials ( ) according to Twidell and Mahhrer, (1982) and Weir,
(1990) as cited in Emmanuel et al.,(2016).
If we come to classify ceiling materials base on the ceiling materials with good or best thermal
efficiency in building, then we can consider the thermal absorptivity for clarifications. Hence, the P
V C and asbestos have the lower absorptivity value and the followed by POP, where the card board
42
has the highest value of thermal absorptivity. Therefore, the P V C and asbestos are the best ceiling
insulating materials in building with best thermal efficiency and then followed with P O P, where
the least ceiling materials best on thermal efficiency in building is card board.
Lastly, we can says that, the lower the thermal absorptivity value irrespective of lower or higher of
thermal diffusivity portrays a good thermal insulation efficiency of ceiling materials in building.
5.3 RECOMMENDATION
1. The builders should concentrate more on the insulator with good thermal efficiency when they
come to the selection of ceiling materials in building.
2. Best on the experience gained in this research, I suggest P V C ceiling as the best ceiling insulators
materials in building.
3. I recommended the Management of Federal University Dutsin-Ma to modernize the lecture
classes that having ceiling which is not good in terms of thermal efficiency, and to stop using them
purposely for the benefit of the student.
4. People should switch from going to the most highly cost ceiling materials in building to the one
with good thermal efficiency.
43
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