The Australian built environment is pivotal to achieving national net-zero targets, yet progress remains slow due to fragmented policy frameworks, low retrofit adoption, and uneven integration of emerging technologies. Despite these challenges, little research has applied a foresight perspective that both defines reproducible scenario thresholds and provides semi-quantitative comparisons tailored to Australia. This study integrates strategic foresight with international benchmarking to develop four scenarios for 2050: Business as Usual, Accelerated Sustainability, Technological Transformation, and Climate Resilience. Each scenario is underpinned by measurable thresholds for renovation rates, electrification, digital penetration, and low-carbon material uptake, and is evaluated through a scorecard spanning five outcome domains, with sensitivity and stress testing of high-leverage parameters. Findings indicate that an Accelerated Sustainability pathway, driven by deep retrofits of ≥3% annually, whole-life carbon policies, and renewable penetration of at least 70%, delivers the strongest combined performance across emissions reduction, liveability, and resilience. Technological Transformation offers adaptability and service quality but raises concerns over equity and cyber-dependence, while Climate Resilience maximises adaptation capacity yet risks under-delivering on mitigation. The study contributes a reproducible framework and transparent assumptions table to inform policy and industry road mapping, suggesting that a policy-led pathway coupling retrofits, electrification, and digital enablement provides the most balanced route towards a net zero and climate-resilient built environment by 2050.