ABSTRACT
Thermal properties refer to characteristics of a material
defining the substance and related to temperature dependent. The most important
thing in building design is the protection of people who live and work within
the environment. The research work identified some common roofing materials
used for building design in Nigeria.. The samples include aluminium
(coated), Zinc and stone coated. The investigation was done using Ohm‟s law and
Frankz Weidman principle. The thermal properties investigated were thermal
conductivity, thermal absorptivity, thermal diffusivity, thermal resistivity
and specific heat capacity. with the view of establishing their suitability as
roofing materials in building design in Nigeria based on climate and weather
condition of particular location. the results show that zinc has the highest
thermal conductivity, thermal absorptivity, and
specific heat capacity and also the lowest thermal diffusivity and
thermal resistivity while stone coated material has the least thermal
conductivity, absorptivity, and specific heat capacity and also the highest
rate of thermal diffusivity, and thermal resistivity Aluminum coated is within
the range of both sample, with thermal conductivity, thermal absorptivity,
thermal diffusivity, thermal resistivity and specific heat capacity. Thus stone
coated material may berecommended
for roofing of building where the temperature is high and zinc may be
recommended for roofing of buildings where temperature is low. For normal
temperature range, Aluminium material may be recommended.
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CHAPTER
ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Provision of housing among other social amenities occupies a
strategic position in most development plans for developing Nations such as
Nigeria (Chukwucha, and Owate, 2002). One of the fundamental requirements of
buildings is the protection of the people who live and work within them from
hash weather. Thus, objective of environmental building design is the creation
of a comfortable yet efficient internal environment (Camilleri, 2000).
The design of the building envelope is crucial towards
attaining an optimal configuration, which responds effectively to environmental
changes in order to reduce their impact. The understanding of energy related
characteristics and the evaluation of the relevant properties of the building
envelope is an integral part of every environmental assessment. Solar energy
affects significantly, the interior environment and the energy requirements of
buildings. (Lattimer & Ouelletes 2006).
However, one way to reduce the heat flux is the use of
radiant barriers which reduce the heat flux through radiation. Most building
materials particularly, roofing materials are good conductor of heat. Materials
like metal and tile are commonly used in the form of sheet metal for roofing in
building construction.
The
knowledge of thermal properties of different roofing material is very important
in the choice of the type of material to be used in the construction of a self-
cooling or passively cooled building design. (Etuk, et al., 2008 & Michael,
et al., 2008)
However, roofing
systems used in the formal and residential sector are predominantly timber or
metal truss systems with tile or profiled steel roofing, generally these
roofing systems will be
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complimented with a plasterboard ceiling, regulations which
require that these roof assemblies are insulated.
Therefore, thermal insulation is applied above the ceiling
to achieve the thermal resistance requirements. The requisite thermal
resistance can be achieved by adding additional layers of fibrous loft
insulation or with reflective foil layers to create air-spaces or by making use
of thermally insulating board products.(Safintra roofing and steel South
Africa, 2016).
In the recent observation, it
has shown that roofing materials used in building design doesn‟t take
sufficient account of climate and environmental factors in the design, most
especially with the regards to the choice of roofing materials to be used.
These situations would increase the energy consumption for heating and cooling
in buildings and affects comfort, health and efficiency. Therefore, it is
important to carry out adequate research on thermal properties of these roofing
materials.
1.2 Aim and Objectives
The
aim of this research is to measure and compare the thermal properties of some
common roofing
materials
in building design in Nigeria.
The
Objectives are;
i.
To identify common roofing material used for buildings in
Nigeria
ii.
To measure and compare specific heat capacity of these materials
iii.
To measure and compare thermal
conductivity as well as to evaluate thermal resistivity of the materials
iv.
To measure and compare thermal diffusivity of material
v.
To measure and compare thermal absorptivity of material
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1.3 Significance of the study
The result of this research would enable the builder in
Nigeria, to choose the best roofing materials for the residential and
industries construction that will prevent any outbreak.
1.4 Scope of the study
This research work focuses on identifying the common roofing
material in Nigeria for building design. The thermal properties of these
roofing materials will then be study comparatively by measuring conductivity,
resistivity, absorptivity, diffusivity and specific heat capacity of the roofing
material. The measurement will be carry out in the laboratory for necessary
computations, at the end of the experiment the result will be show graphically.
1.5 Definition of Terms
Temperature: is measure the
degree of hotness or coldness expressed in terms of any severalarbitrary
scales and indicating the direction in which energy will spontaneously flow,
i.e. from higher body to lower body .Thermometer is an instrument use to
measure the temperature of a system.
Heat (Q): is the transfer of
energy between two objects due to temperature differences. Withoutexternal
agent doing work, heat will flow a hotter to a cooler object. Two objects of
different temperature always interact. Heat can be flow in three different ways
from one object to another through conduction, convection and radiation.
Heat
flux: is the rate of heat energy transfer through a given surface per unit
time.
Thermal properties: any characteristic
of a material defining the substance and related totemperature; e.g.
thermal conductivity is said to be a thermal property, but electrical
conductivity is not.
Weather: is the state of the
atmosphere to the degree of hot or cold, wet or dry calm or stormy, clearor
cloudy. Weather is driven by air pressure, temperature and moisture difference
between one place and another.
Climate: is the
average weather pattern usually taken over a 30–year‟s period a
particular region
and
time.