Buildings produce a constant stream of operational data: temperatures, energy use, equipment status, alarms, occupancy. Most of it comes from the building management system (BMS) that controls heating, ventilation and lighting, from meters, and increasingly from separate IoT sensors. On its own this data says "sensor 4471 reads 26 °C". Linked to BIM's asset and space data, it says "meeting room 3.117 is too warm, and the fan coil unit serving it has a fault".
At a glance
| Sources | BMS (controls and points), energy and water meters, IoT sensors (occupancy, air quality, temperature), access control, lifts |
| Typical protocols | BACnet, Modbus, KNX, LonWorks for building controls; MQTT and web APIs for IoT platforms |
| Naming and tagging | Point naming conventions; semantic models such as Brick and Project Haystack describe what each point measures and what it belongs to |
| Link to BIM | Points mapped to assets (tags) and spaces (numbers) from the model |
| Used for | Energy management, comfort, fault detection, predictive maintenance, occupancy and space utilisation, digital twins |
Why the link to BIM matters
| Without asset and space links | With them |
|---|---|
| "Point AHU2_SAT high" | "AHU-02 supply air temperature high; serves Levels 3–4 east" |
| Energy totals for the whole building | Energy by floor, department or system |
| Occupancy counts per sensor ID | Utilisation per room type, compared with booking data |
| Alarms the helpdesk can't locate | A work order raised against the right asset, in the right space |
What BIM teams can do during delivery
- Agree point naming that includes asset tags and space numbers, in the AIR and the controls specification.
- Model spaces and assets consistently, with the same tags the controls contractor uses.
- Record which asset serves which space (systems and zones) in the model data.
- Hand over a points list linked to tags, not just a BMS backup.
Worked example
An office's BMS has 6,000 points with names like L3_FCU_14_RAT. The controls contractor and the BIM team agreed that FCU numbers match model tags (B01-FCU-L03-014) and that each FCU records the space it serves. After handover, an energy dashboard pulls BMS data, groups it by space and department from the model data, and shows that two meeting rooms on Level 3 are heated all weekend. The fix is a schedule change, found in the first month.
Common mistakes
- Controls point names invented by the controls contractor, unrelated to asset tags.
- Spaces in the model that don't match the BMS zones.
- Collecting sensor data with no plan for who acts on it.
- Treating a 3D model with live sensor readings as a finished "digital twin".
Where to read more
The Brick Schema and Project Haystack communities publish open semantic models for building data. BACnet and other protocols are maintained by their standards bodies (for example ASHRAE for BACnet). Building services bodies publish guidance on controls and metering strategies.