| Author: | Ohene, Eric |
| Title: | Implementation strategy and guidelines for net zero carbon building in an emerging economy |
| Advisors: | Chan, P. C. Albert (BRE) Hsu, Shu-chien (CEE) |
| Degree: | Ph.D. |
| Year: | 2024 |
| Department: | Department of Building and Real Estate |
| Pages: | xvi, 220 pages : color illustrations |
| Language: | English |
| Abstract: | Net zero carbon buildings (NZCBs) are a promising solution for decarbonizing the built environment, addressing climate change, and enhancing the quality of life for building occupants. However, the uptake of NZCB has been slow, and the feasibility remains unclear, especially in emerging economies. This study aims to examine the feasibility of NZCB and proposes an implementation strategy and guidelines for Ghana, a typical emerging economy. To achieve the aim of the study, three main objectives were set: (1) to examine the key driving forces, critical barriers to, and strategies for promoting NZCB in Ghana, and to develop an implementation strategy for NZCB in Ghana; (2) to identify retrofit interventions for existing buildings retrofit to net zero energy in the tropical climate of Ghana, and to develop a guideline for retrofitting buildings to net zero energy in Ghana; and (3) to identify early-stage building design strategies for achieving net zero energy using multi-objective optimization analysis, and to develop a guideline for early-stage design of net zero energy buildings in Ghana. Objectives 2 and 3 focused on achieving net zero energy because building energy use is crucial in achieving the NZCB target. The net-zero energy boundary considered in this study is the onsite operational energy use without consideration for embodied energy due to limited data in the case of Ghana. Therefore, net zero energy was used to refer to the operational phase of NZCB. This study is important for a developing economy such as Ghana, where energy supply remains a critical challenge, and energy efficiency practices are lacking. The study is important to guide stakeholders in selecting cost-effective measures to improve energy efficiency while safeguarding energy security and tackling climate change. It is worth mentioning that while numerous studies have explored the issues addressed in this study, there is a lack of research focusing on the context of developing economies, specifically in many Sub-Saharan African countries, including Ghana. To achieve the research objectives, the study first utilized a comprehensive literature review and questionnaire surveys with construction professionals, and the data was analyzed using various quantitative analysis techniques. Then, a technical analysis of retrofit interventions for existing buildings and early-stage design measures for achieving net zero energy was conducted using simulation and multi-objective optimization analysis. Based on the survey, the study systematically identified key drivers and barriers, covering economic, legislative, skills and knowledge, industry, market, and cultural factors. On the driving forces for NZCB adoption in Ghana, economic drivers were perceived as the most significant for promoting NZCB, followed by the legislative drivers. The top-ranked specific drivers broadly include economic and financial motivations, legislation and regulatory framework, awareness and stakeholder attitude, and demonstrations of low-carbon and green building projects. Using the Best-Worst Method (BWM) and sensitivity analysis, financial barriers were identified as critical factors hindering the adoption of NZCB, followed by skill and knowledge barriers. Interestingly, this study identified that skill and knowledge barriers are more critical than legislative ones, which have been prioritized in many previous studies. The top five barriers militating against NZCB promotion include higher initial investment cost, unavailability of skilled labour, insufficient regulations and policies, lack of public awareness, and lack of stakeholder collaboration. Regarding the strategies to promote NZCB adoption, enhancing industry and public awareness, setting net-zero building regulations, policies, and targets, providing incentives for renewable energy utilization, increasing energy efficiency through user behavioural changes, and promoting green building education and awareness were the top five strategies. Based on the analysis's outcome, a comprehensive strategy framework for promoting NZCB development was proposed. To achieve objective two of the study, which seeks to develop a guideline for existing buildings retrofitted to net zero energy, a typical archetype model was analyzed systematically using parametric simulation. An existing low-rise residential building was audited, and the energy use data was collected over one year to calibrate and validate the energy simulation model. The calibrated model determined energy efficiency interventions and renewable energy potential for achieving net zero energy across four major climate zones of Ghana. The results showed that passive design strategies such as natural ventilation, sun-shading, daylighting, and envelope airtightness transformed the case building, reducing about 48-50% of total energy demand. Moreover, the PV system was used to generate energy to supplement the remaining energy demand with a payback period of 6-10 years. A guideline for retrofitting existing buildings to net zero energy was proposed based on the methods used and the results obtained. Further to the retrofit analysis, objective three proposed a systematic analysis approach and guidelines to optimize the design of residential facilities at the early design stages. The design optimization is based on life cycle cost (LCC) analysis, which considers capital and energy costs over the life cycle of the building. The study consistently shows that LCC-based optimal designs significantly reduced the building’s annual energy consumption, achieving 34-35% energy-saving across the various climates compared to the baseline case. The study provides an optimal path for designing net zero energy buildings and offers guidelines to achieve net zero across the building’s lifecycle. The PV system integration indicates that Ghana's net-zero energy building design is technically feasible and cost-effective across the climate zones considered. However, space availability for rooftop PV systems has to be considered, or alternates such as Building-Integrated PV (BIPV) and other PV installation options must be considered. The study contributes significantly to the net zero and green building literature, particularly for developing economies, and could help policymakers and stakeholders promote the uptake of NZCB. Overall, the study can benefit the construction industry in formulating adequate decarbonization action plans for the built environment. |
| Rights: | All rights reserved |
| Access: | open access |
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