The evolution of blockchain in smart buildings with IoT integration and future prospects

The adoption of Internet of Things (IoT) sensors in smart buildings introduces complex challenges around data privacy, integrity, interoperability, and governance. Blockchain—particularly permissioned and hybrid designs—offers immutability, fine-grained access control, and auditable workflows that can strengthen compliance and trust in building operations. This article synthesizes architectural patterns and operational trade-offs for integrating blockchain with smart-building IoT, focusing on latency-aware data placement (off-chain buffering with on-chain anchoring), identity and consent management, and verifiable telemetry for control loops. Across databases (IEEE Xplore, ScienceDirect, Springer, ACM & Wiley), 553 records were identified; Step 1 excluded 311. After duplicate removal and title/keyword screening (Step 2), 375 papers remained with 178 excluded; abstract screening (Step 3) yielded 336 papers with 39 excluded; introduction/conclusion criteria (Step 4) retained 264 with 72 excluded; full-text review (Step 5) resulted in 131 included studies. Consistently with Table 3, counts progressed from 553 (initial) to 375 (title/keyword), 336 (abstract), and 131 (final full-text). We summarize verified design choices and open issues—cross-chain interoperability, light-node feasibility, and empirical benchmarking for off-chain computing—to guide robust, efficient, and modifiable IoT infrastructures.