The development of a decision-support tool (DST) for selecting best-fit zero-carbon building materials : the case of New Zealand building industry : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Construction in the School of Built Environment, College of Science, Auckland Campus, Massey University, New Zealand

Abstract

The construction sector plays a critical role in national and global decarbonisation efforts due to its substantial contribution to greenhouse gas emissions, particularly through the embodied carbon of building materials. In New Zealand, while policy initiatives such as the Zero Carbon Act 2019 and the Building for Climate Change programme signal a strong commitment to netzero emissions by 2050, practical mechanisms to support early-stage zero-carbon material selection remain limited. Material choices are often fragmented, experience-driven, and constrained by incomplete or inconsistent data, highlighting the need for structured and evidence-based decision support.

This doctoral research addresses this gap by establishing a multi-criteria decision-support framework for zero-carbon material selection in the New Zealand construction industry. Guided by a pragmatic research philosophy, the study adopts a sequential mixed-methods and design science research approach to integrate empirical evidence, expert judgement, and artefact development.

The research is structured across five interconnected phases. First, a scoping review identifies common zero-carbon and low-carbon building materials relevant to the New Zealand context, including timber-based systems, straw bale, rammed earth, adobe, cork, stone, and earth-based materials. Second, a PRISMA-aligned systematic literature review synthesises international and local evidence on material performance and selection criteria. Third, a national survey of construction stakeholders is analysed using descriptive statistics, one-sample tests, and structural equation modelling to identify and weight key material selection factors, namely costeffectiveness, durability, buildability, embodied carbon, availability, and aesthetics. Fourth, a qualitative SWOT analysis evaluates these criteria to capture contextual constraints, risks, and implementation considerations. Finally, the integrated findings are operationalised into a digital multi-criterion DTS.

The study makes theoretical, methodological, and practical contributions by reframing zero carbon material selection as a multi-dimensional decision problem, demonstrating a replicable mixed-method design science approach, and delivering a validated, practitioner-oriented DTS tailored to New Zealand conditions. The research supports more transparent, defensible, and context-sensitive material selection decisions and contributes to advancing zero-carbon construction practice in New Zealand.