Towards zero carbon refurbishment of existing buildings in Aotearoa New Zealand : a decision support framework : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Albany, New Zealand

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Massey University
Listed in 2023 Dean's List of Exceptional Theses
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Refurbishing the existing building stock is considered a fundamental element of reducing carbon emissions towards sustainable development. The renewal of the existing buildings is not only supposed to provide a better, healthier, more comfortable environment for people in which to live and work but also limit global warming, contributing to climate change mitigation. Due to existing buildings comprising the largest segment of New Zealand’s building stock, encouraging the low-carbon performance of existing buildings will contribute to achieve the net-zero carbon target by 2050. As a result, it is crucial to ensure that existing buildings are well-refurbished to reduce whole-of-life carbon emissions. Strategic decision-making in building refurbishment can increase building adaptability, durability, and resiliency, as well as achieve zero-carbon goals. However, it is complex and challenging as the consideration of lifecycle carbon performance must be integrated with other requirements, such as building regulations, client’s expectations, and stakeholders’ values. Before this thesis, limited research has explored the main factors and actors that affect decision-making in reducing carbon emissions and how to better make decarbonisation decisions for building refurbishment comprehensively. This thesis was undertaken to create a critical understanding of the decision-making process that incorporates carbon reduction initiatives in building refurbishment. This thesis aims to improve the decision-making towards zero carbon refurbishment of existing buildings in New Zealand. Following a sequence of multiple qualitative enquiry modes, a multi-method qualitative research design was applied to address the research aim, including literature review, preliminary study using semi-structured interviews, case studies and focus group discussions. Through examining the current practices of building refurbishment and the decision-making process for reducing whole-of-life carbon emissions in building refurbishment, a novel decision support framework towards zero carbon refurbishment of existing buildings in New Zealand was proposed as the main result of this thesis. Findings from this research have revealed that New Zealand’s building and construction industry is in the early stage of transiting to a net-zero carbon built environment, with many barriers to reducing carbon emissions in the design and construction of buildings, such as are financial issues, the shortage of knowledge, capacity and capability, the lack of legislation, and organisational culture barriers. Moreover, stakeholders involved in building refurbishment have faced many challenges in integrating carbon reduction in their decision-making practices in different areas of the pre-design and design stages of the refurbishment process, including (1) inexplicit carbon goal setting, (2) ineffective building condition assessment, (3) deficient and incomprehensive relevant whole-of-life carbon information to support the decision-making, and (4) inconsistent and ambiguous carbon-calculation guidelines and benchmark. The results also emphasise that considering both embodied and operational carbon impacts is critical to maximising carbon reduction in a building throughout its life cycle. Especially, for building refurbishment, the priority should move from reducing operational to whole-of-life carbon emissions. The results from this thesis also provide an in-depth understanding of the characteristics of the decision-making process in practice, lessons learnt for improved implementation of building refurbishment and the effectiveness of collaborative rationality among the diverse stakeholders. Based on theoretical propositions found in the literature and practical knowledge from empirical findings, a comprehensive decision support framework was developed that provides a detailed guideline to better-delivering building refurbishment towards zero carbon. The framework supports the stakeholders involved in building refurbishment to understand the refurbishment decision-making process and requirements for reducing carbon emissions in certain activities, identify areas for addressing carbon issues in the early stages of the refurbishment process, determine relevant information key factors and actors in driving carbon-reduction solutions, and promote stakeholder collaboration and integration in carbon-reduction building refurbishment. This thesis updates both the practical and theoretical understanding of challenges and improvement measures to establish a greater way to support decarbonisation decisions for building refurbishment. The decision-support framework from this thesis offers building stakeholders a more holistic and streamlined interdisciplinary guide to recognise the decarbonisation decision with its required information, expertise, and mechanisms to reduce carbon emissions for the refurbished building throughout the decision-making process in practice. Findings from this thesis are also of relevance to the theoretical and practical knowledge of how the decisions are made to maximise carbon reduction in building refurbishment as a guide for other researchers who are pursuing closely related research topics to that of this thesis.
Buildings, Repair and reconstruction, Sustainable buildings, Design and construction, Sustainable architecture, Green technology, New Zealand, Decision making, Dean's List of Exceptional Theses