System Design and Prototype Validation of a Blockchain‐Based Product Carbon Footprint Accounting System

As climate change intensifies, reliable product carbon footprint accounting requires not only accurate calculation but also auditable multi‐party data management. This study presents a system design and prototype validation of a blockchain‐based product carbon footprint accounting system. The system combines a standard life cycle assessment (LCA) pipeline with a permissioned blockchain, smart‐contract‐based rule execution and auditable on‐chain records. The contribution is an engineering integration and validation framework rather than a new blockchain consensus algorithm. Using 1200 lifecycle records from three product categories, eight enterprises and four regions, we evaluate accounting error, processing efficiency, consistency and tamper evidence under controlled deployment (12 PBFT nodes). Compared with the manual LCA workflow, the prototype improves accounting efficiency by 76.39%, keeps calculation deviations within ±5% (MAPE 2.08%) and reaches 98.5% cross‐regional record consistency. Additional comparisons with non‐blockchain digital baselines show that blockchain mainly improves multi‐party auditability and post‐submission data integrity. The results support prototype‐level feasibility, while source‐data truthfulness and large‐scale‐node performance remain open challenges.