Reducing Embodied Carbon in Buildings: A Delphi-Based Assessment of Expert Evaluated Measures and Future Scalability

The building sector accounts for roughly 21% of global greenhouse gas emissions and 34% of European energy-related emissions, with embodied carbon emerging as a potential leverage point for a climate-neutral construction sector. Although numerous decarbonization concepts exist, their translation into industry practice remains limited, and expert judgment has rarely been used to jointly quantify reduction potential and future scalability. This study applies a two-round Delphi method to collect and consolidate practitioner insights on fifteen embodied carbon reduction measures in the Austrian building sector. Thirty-two experts participated in Round 1 and twenty-six in Round 2, evaluating each measure on a 5-point Likert scale, providing optional percentage reduction estimates, and projecting mid- and long-term scalability for 2035 and 2050. Results show a consistent positive correlation between ordinal and quantified assessments, and identify renewable energy supply for material production, improved cement production, intensified use of recycled materials, and wood and timber construction as priority levers aligned with long-term scalability potential. Life cycle thinking emerged as a systemic transformation enabler despite persistent uncertainty, whereas prefabrication, clay construction, natural insulation, and optimized glazing showed more moderate or context-dependent potential. A comparison with the quantitative literature reveals notable perception gaps: experts underestimate steel-related measures while overestimating improvements in cement, glass, and natural insulation. These findings provide a practitioner-informed complement to life cycle assessment and building-stock modeling, identify knowledge gaps for targeted research and policy support, and deliver actionable priorities for planners, regulators, and industry to advance cleaner construction systems toward climate neutrality.