Assessing the energy performance gap between 6-star and net-zero energy buildings for South Africa
Date
2022
Authors
Analo, Andrew
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Abstract
Energy efficiency in buildings has been systematically coupled with the green-rating of buildings based on systems such as the Star-rating of the Green Building Council of South Africa (GBCSA). Net-zero energy buildings (NZEBs) have also been receiving increased attention as a way of addressing concerns over depleting energy resources (especially for fossil fuels), increasing energy-costs and greenhouse gas (GHG) emissions which contribute to global warming and climate change. With a focus on reduction in contribution to GHG-emissions and thus enhancing climate change mitigation of 6-Star green-rated buildings the study applied a case-study approach based on energy performance of the Department of Environmental Affairs (DEA) Building in Pretoria. Secondary data show that the building’s status quo energy performance is 112kWh/m2/yr. Within the temperate-interior climatic zone for Pretoria (as per energy efficiency regulations for buildings in South Africa), psychrometric chart analysis showed that the building could achieve a higherlevel of thermal comfort through further optimization of passive design interventions. Edge-tool simulation results on full optimization of passive design and energy efficiency interventions indicate that a net-zero energy building (NZEB) performance of the same sized building could achieve an energy performance level of 45kWh/m2/yr, thus revealing an energy performance gap of 67kWh/m2/yr. This translates to 60% savings compared to the status quo 6-Star performance of 3076 291kWh/year. Assessment of roof-area for solar PV system indicated that it is adequate for the energy balance towards a NZEB. Assessment of simple payback period per intervention indicates less than one-year payback period for tenant lighting while tenant equipment indicatesa payback period of just over a year and PV-installation at three-years. The findings indicate that the intervention-costs for migration to NZEB fall within the acceptable range for South African investors (maximum of 3 to 5 years). The above findings indicate that the pursuit of NZEBs would significantly contribute towards mitigation of GHG-emissions and climate change and thus calls for further exploration of pathways towards mandatory NZEBs for South Africa.
Description
A research report submitted to the Faculty of Engineering and the Built Environment at the University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Architecture (Sustainable and Energy Efficient Cities)