School of Engineering (SEng.) Collections

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Now showing 1 - 5 of 306
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    Assessment of thermal comfort, air quality and energy performance of naturally ventilated residential buildings in Kampala City, Uganda
    (Makerere University, 2025) Kajjoba, Derrick
    Low-income households in Uganda and similar tropical regions predominantly depend on natural ventilation to achieve Indoor Environmental Quality (IEQ) conditions due to limited access to and affordability of mechanical cooling systems. Factors such as building orientation, ventilation design, building envelope materials, and occupant behavior shape the effectiveness of natural ventilation in providing IEQ conditions and reducing building energy demand. Despite its significance, research on the effectiveness of natural ventilation on thermal comfort, air quality, and energy performance of low-income tropical residences remains scanty. This study explored the role of natural ventilation (NV), outdoor environment (OE), and building design in shaping indoor air quality (IAQ), occupant health (HI), thermal comfort, and energy performance in low-income housing in Kampala, Uganda. A mixed-methods approach, including questionnaire surveys, the Delphi technique, statistical modeling using IBM® SPSS® Amos V24, and building simulation using IES VE V2024, were utilized to examine the relationships between variables. The findings revealed a strong positive correlation between NV, IAQ, and HI, highlighting the importance of natural ventilation in low-income households. Building factors like orientation, window type, and roofing materials impact thermal comfort, with North- and East-facing homes and clay tile roofs offering better indoor conditions. Despite utilizing adaptive measures, many residents expressed dissatisfaction with the thermal environment, highlighting the need for optimized building designs, passive cooling strategies, and urban greenery to enhance comfort. Simulation results demonstrated substantial improvements in thermal comfort, Predicted Percentage of Dissatisfied (PPD), and internal gains with the test model, achieving a 44.3 % and 72.7 % annual reduction in discomfort hours above 28 °C in the living room and master bedroom, respectively. Model validation highlighted that the test model outperforms the base model and the sample buildings, highlighting the effectiveness of the proposed building envelope and orientation modifications. Utilizing the Delphi technique, the key building sustainability indicators tailored to Uganda include energy optimization, advanced construction technologies, and natural ventilation design, among others. This research provides critical insights for policymakers, practitioners, and researchers seeking to advance energy efficiency and sustainability within Uganda's built environment. These findings underscore the importance of sustainable building practices and contribute to achieving SDGs 3, 7, 11, and 13 by promoting health, energy efficiency, resilient urban environments, and reduced greenhouse gas emissions in tropical regions.
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    A model to predict occurrence of head-on traffic crashes along Kampala–Masaka road
    (Makerere University, 2025) Mwesiga, Asbert
    The study evaluates the influence of geometric factors and traffic factors in the causation of head-on traffic crashes on a two-lane rural highway in Uganda using Negative Binomial Regression (NBR) Model. Head-on traffic crashes data for a period of five years (2013 to 2017) was obtained from Uganda Police Traffic Accidents Register (TAR). The Traffic Accidents Register was accessed at different police stations along Kampala–Masaka road. A total of ten blackspots with the highest frequency of head-on traffic crashes were selected for this study. Geometric factors were extracted from as-built drawings obtained from Uganda National Roads Authority while others were measured using tape measure and measuring wheel. The free flow speed data was collected by mounting a tripod camera near the road for five hours to collect video recording at the study locations. Classified manual traffic counts were carried out at the ten blackspots to obtain traffic volume data. Aerial drones were flown over study points where video footages were extracted. The video footages were analysed by Kinovea software to generate passing manoeuvres data i.e. speed of the passed vehicle in the manoeuvre and time taken by passing vehicle to complete the manoeuvre. The Negative Binomial Regression Model results indicated that all the independent variables used this study were statistically significant at 95% confidence level. The performance of the model was evaluated by running the model on seven different sets of data collected at seven locations. The performance metrics used was Mean Absolute Percentage Error (MAPE) which was computed at each location. The NBR model results indicated that 85th percentile of free flow speed was the greatest predictor variable to the causation of head-on traffic crashes while time required to complete the manoeuvre was the least predictor variable to occurrence of head- on traffic crashes. Sensitivity analysis was conducted and it was determined that operating speeds greater than 105 km/hr would cause higher likelihood of occurrence of head-on traffic crashes on two-lane rural roads. It was recommended that motorists should drive at speeds less than 105 km/hr, the absolute vertical grade should be less than 8%, time required by passing vehicle to complete a manoeuvre should be less than 6 seconds and for two-lane highways with ADT value exceeding 9,800 vehs/day, an additional lane should be provided for heavy vehicles.
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    Towards the improvement of thermal comfort in residential houses in Kampala city
    (Makerere University, 2024) Kamulegeya, Obed
    Climate change and global warming continue to present several difficulties. Buildings used for business and residences consume a lot of energy. Due to the rise in human comfort needs and services, this consumption significantly rises each year. As a result, the residential sector uses a large amount of energy globally. This necessitates a Net Zero Energy Building (NZEB) strategy that places a focus on bridging the energy supply and demand gap for renewable energy sources. Although NZEBs play important roles in smart cities' energy efficiency, the potential contribution of NZEB to Uganda's residential sector has not been adequately explored in the literature. This study aimed at creating a thermal comfort model for residential homebuilders to use when designing envelopes. The specific objectives included developing a NZEB model for Kampala city homes to increase their thermal comfort and validate the model, quantifying the thermal comfort needs of residential buildings using predicted mean vote (PMV) and predicted percentage of dissatisfaction (PPD), and suggesting considerations for designing homes in Kampala. ASHRAE 55 standard utilizing the Center for the Built Environment (CBE) tool. Results from the CBE tool revealed that the PMV of residential buildings in Kampala with elevated air speed during sleeping hours, or at night, was 0.48. Standard Effective Temperature (SET) = 27.7 °C, Dry Bulb Temperature (DBT) = 24.0 °C, PPD = 10%, Cooling effect = 3.5 °C and the Sensation is neutral. These results were validated on a python simulation whose results show a close relationship with the results obtained from the CBE tool. The study identified several crucial factors required when building in Kampala city. These included air temperature, radiant temperature, air speed, air humidity, thermal insulation, ventilation, windows and glazing, solar heat gain and thermal mass. The amount of energy needed to provide light, heat, or cool a given building depends on its location. According to the study, the factors that were considered when building these structures need to be reviewed for Kampala residents to enjoy living there. The study identifies better design technologies like, putting a cladding system with movable louvers, water saving in basement, use of natural ventilation, adopting an integrated building system, utilization of thermal mass and radiation cooling and heating panel system for residential structures
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    Techno-economic evaluation of probable hydrogen production technologies for iron ore reduction
    (Makerere University, 2025) Male, Ibrahim
    The annual global production of crude steel is expected to reach 2.4 billion tons by 2040, with 73% of the process employing the blast furnace and basic oxygen converter route which emits large amounts of CO2. A potential solution is to use H2 as a reducing agent. A systematic literature review conducted identified H2 production technologies including, Alkaline electrolysis (AE), proton exchange membrane (PEM), solid oxide (SOE), anion exchange membrane (AEM) electrolyses, thermolysis, photolysis, bio photolysis, photo fermentation, dark fermentation, pyrolysis, gasification, combustion, liquefication, steam methane reforming (SMR), partial oxidation (PO), auto thermal reforming (ATR), and ammonia reforming (AR). NASA's technology readiness level (TRL) scale ranking revealed SMR, AE, and PEM processes were the most mature, with TRLs of 8-9 (SMR) and 6-7 (AE and PEM). Schematic diagrams were developed using Aspen Plus®V10 software for plant output of 20 kgH2/hr. An economic analysis showed that PEM offered the lowest levelized cost of H2 (LCOH) at $1.88/kg compared to AE at $4.53/kg and SMR at $2.81/kg. Furthermore, the sensitivity analysis showed that; PEM responds well to variations in material feed, operating temperature, and pressure. AE exhibited better stability across temperature changes. PEM proved the most promising due to less design complexity and the lowest LCOH.
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    Assessment of strength and curing time of enzyme improved mountainous soils for use as G30 material for Budibugyo area
    (Makerere University, 2021-09-21) Musinguzi, Begumisa
    Unsuitable soils for road construction can be improved by a process called stabilization. This is the addition of additives to the soil in order to improve its engineering properties. The most common means of stabilization is by use of lime, cement or fly ash. These means of stabilization have proved to be expensive and are not environmentally friendly. In addition, these traditional/ conventional means of stabilization are not effective in stabilizing the soils in the project area since these soils have a high cation exchange capacity. These concerns have led to the use of non-traditional stabilizers such as enzymes. By definition, an enzyme is an organic catalyst that speeds up a chemical reaction, that otherwise would happen at much slower rate, without itself becoming a part of the end product. This study examined the use of enzymes as stabilizers and was aimed at determining the effectiveness and suitability of using two enzymes code named; ENZ I and ENZ II in improving the properties of inferior cut materials on Bundibugyo roads for G30 quality standard. Representative samples were extracted and taken to the laboratory. The research was mainly based on laboratory testing of plasticity and strength parameters of the soils treated with the enzymes and curing them over a period of 28 days. Results show that indeed the enzymes alter the properties of the soil. ENZ I and ENZ II both lead to a reduction in PI of the soils being tested. ENZ I has the greatest effect on California Bearing Ratio by increasing it by 65.3% whereas the behavior of ENZ II is not consistent over the 28 day curing period for the samples tested. ENZ I can therefore be recommended for road projects of low design class and with soils of medium range properties. Curing has an effect on the performance of the enzymes. The evidence of this is exhibited in the improvement of the engineering properties of the soils to meet G30 quality standard as the curing period increases.