COMPARATIVE STUDY OF THERMAL PROPERTIES OF SOME COMMON ROOFING MATERIALS IN NIGERIA
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.
1.1 BACKGROUND TO 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