Optimizing Smart-Home Energy Systems Through Energy-Efficient Off-Chain Blockchain-Based Attribute-Based Access Control (ABAC): A Hybrid LightGBM Approach

The widespread deployment of Internet of Things (IoT) technologies in smart-home energy systems has increased the demand for secure, context-aware, and energy-efficient access control (AC) mechanisms. Although blockchain-based AC provides immutability, auditability, and fine-grained policy enforcement, its dependence on on-chain decision-making introduces significant computational latency and energy overhead, limiting its suitability for resource-constrained IoT environments. This paper proposes Optimized Dynamic-Attribute-Based Access Control-IoT (ODABAC-IoT) , a hybrid off-chain and decentralized ABAC framework that combines off-chain LightGBM inference with selective on-chain verification to reduce blockchain workload while preserving trust and transparency. This work focuses on improving the computational efficiency, latency, and energy consumption of blockchain-enabled AC within smart-home energy systems, rather than directly optimizing physical energy consumption. In the proposed framework, high-confidence access requests are evaluated off-chain, whereas uncertain requests are forwarded to smart contracts for final validation. This hybrid decision-making strategy reduces unnecessary blockchain transactions, lowers latency, and improves computational efficiency without compromising security. Experimental results demonstrate up to 65% reduction in blockchain transaction volume, 64% improvement in latency, and 65% reduction compared to on-chain ABAC and 50% compared to hybrid blockchain approaches. These gains correspond to a reduction in daily blockchain energy consumption from 10 kWh to 3.5 kWh in a representative household scenario. The results indicate that ODABAC-IoT improves scalability, energy efficiency of the digital control layer, and responsiveness in IoT-enabled smart home energy systems, offering an effective pathway toward energy-aware and secure AC in the digital infrastructure of smart home energy systems.