Digital Innovation Across Functional Subsystems of Prefabricated Construction in China: A Patent Analysis

Prefabricated buildings are assembled from components designed, manufactured, transported, installed, and operated by different participants. Digital technologies can give these distributed activities a shared description of component geometry, identity, status, and quality, but their value depends on information remaining usable at each handover. This study examines where digital inventive activity is located within that system and how its technical concerns change over time. We classify 538 retained Chinese granted invention patents by functional subsystem and filing period and then compare subsystem counts, subsystem-specific latent Dirichlet allocation topics, and cross-period semantic associations. Standardized design, on-site assembly, and digital management account for 434 patents (80.67%), with off-site manufacturing, intelligent operation, and integrated delivery less represented. Later themes draw greater attention to component parameterization, quality and assembly control, and management integration. The findings map uneven inventive representation and proposed technical solutions that increasingly address interfaces; they do not show realized coordination, environmental improvement, or that low-patenting functions are bottlenecks. As a diagnostic input to systems engineering, the framework can indicate which functional handovers merit requirements, ownership, traceability, and performance investigation.