Civil & Environmental Engineering

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Browsing Civil & Environmental Engineering by Author "Agbo, Onjefu L."

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    COMPREHENSIVE STUDY ON THE IMPACT OF USING AGRICULTURAL RESIDUES FOR ENHANCING BUILDING ENERGY PERFORMANCE IN NAMIBIA
    (2020-11) Agbo, Onjefu L.
    This research work aimed at an understanding of the impact of using local agricultural residues to enhance building performance in Namibia. As human lifestyles improved with the emergence of high economic growth and technologies, the increasing demand for energy in Namibia as a developing country is posing a serious challenge to government and lawmakers in the allocation of funds for appropriate researches and technologies. One such appropriate kinds of research involve developing appropriate material technologies that will improve energy efficiency in the form of using agricultural residues/wastes readily available in Namibia. Like other developing countries, the building sector accounts for approximately 40% of total energy usage in Namibia. For that purpose, the efficient use of energy within buildings is a needed requisite to alienate against rising energy costs and contribute towards decreasing global greenhouse gas emissions. Namibia´s energy usage of buildings closely reflects these global trends and this research therefore aimed at validating its results through the construction of rigs following the design concept of the prototype of the EEBN (Energy Efficient Building in Namibia) research project at the Namibia University of Science and Technology campus that was designed, constructed and equipped through funding from EEP (Energy Efficiency Programme), in partnership between NUST and Carinthia University of Applied Sciences Austria. Through appropriate mixed designs of well-selected locally available agricultural residues, insulating boards and bricks of standard sizes were developed, and results validated through the construction of rigs. Thermal conductivities and transmissibility of the insulating boards together with compressive strength, water absorption were also measured for bricks to measure the degree of thermal effectiveness/efficiency of a standard residential building. This is to establish how the use of affordable and readily available local materials can be used to develop high-quality and energy- efficient building materials which when used in building construction will improve the comfort level of occupants without the use of conventional heating and cooling devices. Vary mixed percentages of residues of maize, millet, rice, and cow dung were designed to develop eleven 220cm by 110 cm by 40 cm board samples (labelled AK) from residues of maize, millet, rice, and cow dung. The samples were compacted, sun-dried for 7 days, and tested for thermal conductivity and thermal resistivity using a thermal conductivity test machine EP500e. Results from the eleven samples tested revealed that sample C (composed of 10% maize, 10% millet, 30% rice, and 40% cow dung) gives the lowest thermal conductivity (i.e. of 54.65 mW/(m*K)) and the highest thermal resistivity (i.e. 0.6935 m2K/W), hence a very good thermal efficiency as compared with sample A (composed of 40% maize, 30% millet, 10% rice and 20% cow dung) that gave the highest thermal conductivity and lowest thermal resistivity, hence considered poor thermal efficiency. Regression analyses conducted between the best (i.e. sample C) and the worst (i.e. sample A) revealed an R2 value of 95% and 91% respectively Test rigs were constructed and equipped with appropriate devices both inside and outside. Wide- ranging measurements were conducted, and results related to thermal behaviour of the interior at fluctuating changes in temperature at the exterior especially at extreme summer and winter periods were obtained. The three prototype Rigs, with varying compositions, were designed and built using standard building procedures. Rig A (TAR 1) with 150 mm thick internal and external walls; made of standard bricks of 7 MPa, insulated with a compacted mixture containing 20% (wt.) Maize, 10 % (wt.) Millet, 30% (wt.) Rice and 40% (wt.), 30% (wt.) Cow dung; Rig B (Tamb2) 40% (wt.) with Maize, 30% (wt.), Millet, 10% (wt.), 20% (wt.), 20%wt. Marble dust and C (TNo3) that serve as control rig. Outside and inside temperatures of the Rigs were monitored during the warm (September 2017 - March 2018) and cold (April to August – 2018) seasons. Temperature and humidity sensors installed at critical positions in the interior of the building were connected to the symmetron data logger. Results of the three design concepts revealed that TAR 1 (Rig A) attained maximum and minimum temperatures of 24.40C and 14.80C, and humidity of 26.4% during winter and 29.60C and 19.30C during summer with an average humidity of 21.1%. Tamb2 (Rig B) recorded a maximum and minimum temperature of 31.220C and 18.70C during summer with a relative humidity of 20.3%. During winter Rig B attained an average temperature of 22.600C. Furthermore, Rig C (TN03) recorded 32.220C and 21.700C in summer and winter respectively. From the results, it can be deduced that Rig A (TAR 1) with compositions of 20% (wt.) Maize, 10 % (wt.) Millet, 30% (wt.) Rice and 40% (wt.), 30% (wt.) Cow dung; had the best performance. Simulation on results obtained from the rigs was also done using Ansys software. This research showed that results from both software and measured are approximately the same.