3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Assessing potential for net-zero energy building retrofits in commercial buildings using on-site photovoltaic (PV) generation: a case study of Durban-South Africa(2019) Davies, GarethRetrofitting existing buildings towards NZEB (net-zero energy building) offers significant benefits in terms of reducing operational electricity consumption and operating costs as well as reducing GHG emissions. The increased efficiency and economic cost competitiveness of renewable energy technologies, as well as the advances in building science and energy modelling, continue to evolve along with the increased demand for energy security, thus allowing for advancement of NZEB. But to what extent is NZEB viable for all existing commercial buildings, and what are the technical and contextual parameters that would influence the potential of NZEB retrofits? The study substantiates on these questions via a simulated performance-based analysis of four existing commercial buildings in Durban, with energy modelling and simulation as the primary data sources. The simulation data were then applied towards the assessment of the potential of retrofitting for NZEB based on passive interventions in conjunction with energy-use optimisation of active/mechanical systems and integrated RE technology in the form of site PV. The study demonstrated a reduction of 27% - 56% in overall grid-electricity consumption and carbon emissions across the case study samples. Lower FAR buildings achieved greater percentage reductions in grid-electricity consumption due to less site shading combined with larger site-area (for PV) to net floor area ratio. Longer operating schedules were also found to increase annual energy consumption while also being better suited for on-site PV generation due to consistent levels of self-consumption. User-density was found to have less significant impacts on overall electricity consumption. Payback periods for NZEB-targeting interventions were enhanced by the recent introduction of the RE tax allowance, which reduced overall payback periods by 2-3 years with two of the case study buildings achieving 4-6 year yields which is considered to be within an acceptable range based on prevailing efficiency and cost levels of the assessed interventions. The study found that the efficacy and practicality of on-site generation PV is limited by grid constraints for building use-types with a high export balance, and for certain high-density sites due to high shading levels. The study recommends smart-grid integration which would connect buildings that can benefit from either consuming or exporting RE and thus ensure annual energy consumption and GHGemissions in the sub-sector could be brought into line with the 38% reduction compared to the 2050 Nationally Determined Contribution GHG emission reduction targetItem Decentralised electricity generation through rooftop solar photovoltaics (PVs) in Zambia : a case study of the engineering institute of Zambia (EIZ) office building project, Lusaka(2018) Samunete, JosephWhereas there has been significant study and development of national strategic plans on electricity generation from renewable energy in general in Zambia, specific studies and research on decentralised electricity generation via rooftop solar PVs from buildings and their potential to enhance Zambia’s electricity generation goals have not systematically been done. The study applies a case study of the Engineering Institute of Zambia office building that is at construction stage but is determined to incorporate a rooftop solar PV system. Using DesignBuilder and Energyplus simulation software, the building was modelled and analysed for this potential. In addition, based on interview data from various experts and secondary data from national plans, the study evaluated policy, regulatory and market frameworks which could catalyse the increased deployment of such systems in Zambia. Using financial analysis tools of payback period, return on investment and net present value the study undertook a number of business case scenarios in order to conceptualize a responsive business model. The study finds that from the initial estimate, the available roof space had the capacity to net out the baseline annual electricity consumption of 287,707kWh and generate a surplus of 63,519kWh/year before optimisation. Optimisation of the baseline consumption through a combination of two viable energy efficiency interventions reduced the baseline annual consumption by 35% to 186,904kWh with related payback period of nine years, ROI of 518% over a 25 year analysis period and a NPV of 623,344.00 ZMK. Based on these findings, three business case scenarios for the solar PV system were analysed and two out of the three were adopted. One scenario assumed a net-zero building and another one assumed that the surplus electricity generated on non-business days is exported to the grid were adopted. Following this finding, a business model centred on an integrated energy service company (IESCo) was identified as the most appropriate model to respond to the uptake barriers of this technology and thus leverage on the emerging progressive support mechanisms. The overall findings of the study thus support the working hypothesis of the study which deemed that through the framework of a responsive business model, decentralised electricity generation through rooftop solar PV can greatly enhance energy security and mitigate GHG-emission for Zambia.