Data assetization is an important trend in the digital transformation of the construction industry, but it is still in its nascent stage. This study addresses the characteristics of building data and proposes a technology system for data assetization, comprising three steps: security, standardization, and valuation. The study also develops a method for automatic generation of metadata based on Large Language Models (LLM). By examining a case study from a construction enterprise, the feasibility and value of the building data assetization technology system are validated. The study analyzes current challenges and future research directions. Overall, building data assetization facilitates data exchange and sharing, maximizes the potential value of data, and drives the digital transformation of construction enterprises. However, further research is needed on BIM data anonymization technologies and market mechanisms.