Brick Bacnet Mcp

brick-bacnet-mcp

A read-only BACnet/IP gateway that exposes building automation point databases to LLM agents via MCP, with Brick + Project Haystack semantic tagging at ingest time.

Why this exists

The research note this implementation came out of is at https://habchy.dev/research/bacnet-msi-semantic-gap. A version of the same article is also published at AutomatedBuildings.com (link will be added when the AB.com edition goes live).

Short version: vendor agentic platforms (JCI OpenBlue, Honeywell Forge, Siemens Building X, Tridium Niagara 5) keep their semantic AI layer inside their own controls portfolios. Independent MSIs running mixed-vendor 5-50 building portfolios have BACnet point databases but no clean way to expose them in semantic-tagged form to external LLM agents. This gateway is one answer to that gap.

ezhuk/bacnet-mcp does read and write at the BACnet protocol layer with no semantic normalization. This project sits beside it: it adds the Brick + Haystack tagging step at ingest and restricts the v0.1 surface to read-only for a tighter compliance footprint.

What it does (v0.1)

• Discovers BACnet/IP devices on the local broadcast domain (Who-Is, I-Am)
• Enumerates objects per device (AI, AO, AV, BI, BO, BV, MSI, MSO, MSV, Schedule, Calendar)
• Reads present-value, units, and description per object
• Tags each object with a Brick class and a Haystack tag set using rule-based mapping (rules are extensible via YAML)
• Exposes the tagged topology to any MCP host via four tools: list_devices, list_objects, get_object_value, get_tagged_topology

What it isn't (v0.1)

• Not a write path. WriteProperty is intentionally out of v0.1 for the compliance-surface reasons noted in the research article.
• Not a Niagara station integration. Fox protocol / Niagara module wrapping is a separate design.
• Not an FDD or analytics platform. The tagged topology is meant to be consumed by downstream FDD or LLM-agent workflows. This gateway is the ingest layer only.
• Not a UI. Output is MCP only. Pair it with Claude Desktop, Cursor, or any other MCP host.
• Not BACnet/SC. v0.1 is BACnet/IP only. Secure Connect is a v0.2 consideration.
• Not 223P full schema parity. v0.1 uses the simplified Brick + Haystack mapping. Full 223P entity model is a v0.2 candidate.
• Not multi-site federated. v0.1 handles one broadcast domain at a time.
• Not authenticated. v0.1 runs in a trusted local network environment.

Install

pip install brick-bacnet-mcp

Or from source:

git clone https://github.com/Yveshby27/brick-bacnet-mcp
cd brick-bacnet-mcp
pip install -e .

Python 3.11 or later required.

Quick start

Create a config file config.yaml:

bacnet:
  local_device_instance: 555001
  broadcast_address: 192.168.1.255
  polling_interval_seconds: 30
rules:
  brick: src/brick_bacnet_mcp/rules/brick_rules.yaml
  haystack: src/brick_bacnet_mcp/rules/haystack_rules.yaml
mcp:
  transport: stdio  # or "http" for a hosted MCP host
  http_port: 8080   # only if transport == http
log_level: INFO

Run the MCP server:

brick-bacnet-mcp --config config.yaml

Or wire it into Claude Desktop:

{
  "mcpServers": {
    "brick-bacnet": {
      "command": "brick-bacnet-mcp",
      "args": ["--config", "/path/to/config.yaml"]
    }
  }
}

Example interaction

With the server running and the simulator active (or a real BACnet/IP network reachable), an MCP-capable LLM can run:

> User: List all the air-handling units across the building. > > Agent (via MCP tool): calls get_tagged_topology(filter="brick:AHU") > > Agent response: Found 3 AHUs. AHU-1 has 5 child points (dischargeairtemp, returnairtemp, supplyfanstatus, mixedairdamperposition, outsideair_temp). AHU-2 ... AHU-3 ...

See [examples/](examples/) for full runnable scripts.

Checking coverage on your building

The starter rule library targets common US-style object-name conventions (OAT, DAT, ZNT, CHWS, AHU-1, etc.). Real-world mixed-vendor portfolios use wildly different naming. Before assuming the tool is broken or working, run:

brick-bacnet-mcp --coverage-report --config config.yaml

This does one discover + enumerate + tag cycle against your network and prints:

• Total objects discovered
• Brick / Haystack match percentages
• Top 20 most-common object names that no rule matched (use --top-unmatched N for a different count)
• Top 10 hottest rules

Use the unmatched list to extend the YAML rule files for your naming convention. A first-run match rate of 30-50% is normal for a portfolio that hasn't been calibrated yet; 70%+ is what you'd want before relying on the tagged topology for LLM queries.

How tagging works

The tagger applies YAML-defined rules to map BACnet object names and units to Brick classes and Haystack tag sets. The default rule set covers about 50 common HVAC, lighting, and metering object-name patterns. Users override or extend by editing src/brick_bacnet_mcp/rules/brick_rules.yaml and haystack_rules.yaml locally.

Example rule (Brick):

- pattern: '(?i)^(oat|outside_air_temp|outsideair)$'
  units: ['degF', 'degC', '°F', '°C']
  brick_class: 'Outside_Air_Temperature_Sensor'

See [docs/RULES.md](docs/RULES.md) for the rule grammar and override conventions.

Architecture

See [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md). Short version:

• discovery.py runs Who-Is broadcast, captures I-Am responses, caches device metadata
• reader.py enumerates the object list per device and polls present-value at the configured interval
• tagger.py applies Brick + Haystack rules to each enumerated object
• topology.py assembles the tagged objects into a queryable graph
• server.py exposes four MCP tools over stdio or streamable HTTP

Roadmap

v0.1 is a research instrument. The roadmap below is what the research article flagged as worth doing next IF v0.1 gets enough sustained-use signal to justify extending. None of it is committed pre-signal.

• v0.2: COV subscription support, BACnet/SC, 223P full schema parity, SkySpark / FIN Haystack-store passthrough
• v0.3+: Optional write path behind explicit opt-in, multi-site federation, authentication layer for non-local deployment

Acknowledgments

• ezhuk/bacnet-mcp for the prior-art MCP + BACnet integration that this project builds beside
• bacpypes3 for the BACnet protocol library
• Project Haystack for the Haystack tagging vocabulary and community
• Brick consortium for the Brick schema
• The named MSI voices whose published positioning this research builds on: Brian Turner (Adaptive Buildings), Marc Petock (Lynxspring), Tom Shircliff and Rob Murchison (Intelligent Buildings LLC), Jim Meacham (Altura Associates), Therese Sullivan (BuildingContext), Alper Üzmezler (BASSG)

License

MIT. See [LICENSE](LICENSE).

Contributing

See [CONTRIBUTING.md](CONTRIBUTING.md). PRs welcome for rule library extensions, documentation, examples, and test coverage. Larger changes (write path, non-BACnet protocol support, UI, FDD logic) are out of v0.1 scope. Open an issue first to discuss before submitting a PR.

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Yveshby27
• Source: Yveshby27/brick-bacnet-mcp
• License: MIT

Install and usage instructions live in the source repository linked above.