Achieving zero carbon emissions in the construction sector: The role of timber in decarbonising building structures

This comprehensive and policy-relevant study provides a compelling, data-driven case for accelerating timber adoption in the construction sectors of Chile and the UK to meet climate targets. The multi-scenario approach (BAU, TA, ER, OPT) effectively disentangles the contributions of material substitution versus industrial decarbonization, a crucial distinction for policymakers. I have several points for discussion and questions: System Boundaries and Leakage: The analysis focuses on 'cradle-to-gate' embodied carbon of structural materials. How might the conclusions be affected if the system boundary were expanded to include a) operational energy (given timber's potential thermal properties), b) maintenance/replacement cycles (durability of timber vs. concrete), and c) indirect land-use change (iLUC) effects if increased timber demand leads to unsustainable forestry practices? A sensitivity analysis on these factors would strengthen the robustness of the policy recommendations. End-of-Life (EoL) Assumption: The model's optimistic outcome heavily relies on the assumption that timber is reclaimed and reused at EoL, thus retaining its stored carbon. Given the current lack of mature deconstruction and reclaimed timber markets in both countries (as noted), what specific policy instruments (e.g., mandatory deconstruction plans, material passports, landfill taxes) are most critical to bridge this gap between the modeled ideal EoL and current practice? A minor suggestion: The report is rich in data. A summary table comparing key input parameters (e.g., assumed emission reduction rates for concrete/steel, timber adoption rates per building height, carbon storage factors) between Chile and the UK would help readers quickly grasp the comparative drivers of the results.