COMPARATIVE STUDY OF THERMAL PROPERTIES OF SOME COMMON ROOFING MATERIALS IN NIGERIA

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 be recommended 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.

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 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;

1. To identify common roofing material used for buildings in Nigeria
2. To measure and compare specific heat capacity of these materials

• To measure and compare thermal conductivity as well as to evaluate thermal resistivity of the materials

1. To measure and compare thermal diffusivity of material
2. To measure and compare thermal absorptivity of material

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 several arbitrary 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. Without external 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 to temperature; 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, clear or 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.

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