I am often trying to understand the same question you are. Here is a start from my first discussion with Gemini
Can existing BACnet create a Knowledge File, RDF file, and TTL files as per ASHRAE’s 223 standard?
Good discussion. How do we leverage our existing BACnet resources?
No, existing BACnet on its own cannot inherently create or generate a Knowledge File, RDF file, or TTL file.
To understand why, we have to look closely at what ASHRAE Standard 223 actually does and how it interacts with the physical protocol layer.
https://docs.open223.info/overview
The Separation of Protocol (BACnet) and Model (223) www.ashrae.org
Traditional BACnet is a data communication protocol designed to transmit real-time telemetry (the syntax). It handles things like Analog-Input objects, binary values, and trend logs. However, native BACnet objects don’t understand physical topology. A BACnet controller doesn’t inherently know that it is connected to a specific pipe, that it conveys air, or that it serves a particular physical space.
www.ashrae.org+ 1
ASHRAE 223 is an upper ontology—a semantic data model—built entirely on W3C Semantic Web standards. It explicitly uses RDF (Resource Description Framework) graphs and TTL (Terrestrial Turtle) files to map out the meaning, composition, and physical connections (topology) of a building’s assets.
https://docs.open223.info/overview
How the Integration Actually Happens
While existing BACnet hardware doesn’t magically spit out a .ttl file, ASHRAE 223 explicitly acts as a bridge between the two layers.
docs.open223.info
- External References: In an ASHRAE 223 model, a semantic property (like an
ObservablePropertyfor discharge air temperature) includes a dedicated pointer called an External Reference. docs.open223.info - The BACnet Link: This reference explicitly points straight to the specific BACnet Device ID, Object Type, and Instance ID handling that data point. docs.open223.info
A 223 model does not store real-time data. Instead, an external piece of software, an open-source tool (like those in the Open223 ecosystem), or a modern AI-Native edge controller ingests the BACnet network objects, reads the 223 standard ontology (223p.ttl), and weaves them together to output the final Knowledge File.
https://docs.open223.info/overview
The Semantic Interoperability Working Group (SI-WG) under the BACnet committee is actively working on enhancements to the BACnet standard—such as advanced engineering for Tags properties within BACnet objects—to make this translation much smoother. However, the creation of the actual RDF graph remains a function of the cognitive modeling software layer, not the legacy BACnet device itself.
BACnet Committee+ 1 https://bacnet.org/working-groups/si-wg/
The Semantic Interoperability Working Group is developing a comprehensive approach for applying semantic formalisms to represent the context of building system data and the relationships among associated building systems and components. The objective of this work is to enable applications to find and understand information automatically. This will facilitate the development and implementation of building analytics tools and enterprise knowledge applications that can implement a number of building system functions.
This working group is the home for the development of the proposed ASHRAE standard 223P Semantic Data Model for Analytics and Automation Applications in Buildings. It is also developing guidance on enhancements to the BACnet standard related to the use of Tags properties in BACnet objects.
