  Building metadata is regarded as the signpost in organizing massive building
data. The application of building metadata simplifies the creation of digital
representations and provides portable data analytics. Typical metadata
standards such as Brick and Haystack are used to describe the data of the
building system. Brick uses standard ontologies to create building metadata.
However, neither Haystack nor Brick has provided definitions about the Variable
Refrigerant Flow (VRF) system so far. For years, both Brick and Haystack
working groups have been discussing how to describe VRF in their schema, mainly
about the classification of VRF and the definitions of VRF units. There were no
settled solutions for these problems. Meanwhile, the global VRF market is
growing increasingly fast because of the energy efficiency and installation
simplicity of the VRF system. It is needed to have the metadata to describe VRF
units in buildings for data analysis and management. Addressing this challenge,
this paper extended Brick Schema with the VRF module and verified the Brick VRF
module. Then, the model and the service framework were developed and applied
for a building in China. The framework can serve portable energy analysis for
different areas. The VRF module of this paper provides a possible solution for
the expression of the VRF system in the building semantic web. The works in
this paper will support semantic web in automation strategies for building
management and scalable building operation.
