What goes in a BAS points list
By Bassirou Thiam, building automation engineer · Updated
A BAS points list is the table of every input and output each controller handles: point name, point type (AI, AO, BI, BO or a software value), the field device it reads or drives, and where that device sits. Specs ask for one per system controller, and the sequences and graphics refer to its point names.
Which columns does a points list need?
A typical guide specification asks for a point list for each system controller including inputs and outputs, point numbers, the controlled device associated with each point, and the location of that device. Most contractors add a few columns that save time at checkout:
| Column | What it holds | Example |
|---|---|---|
| Controller | The controller or panel that owns the point | AHU-1 controller, TCP-2 |
| Point name | The unique name used everywhere: controller, front end, sequences | AHU1-SAT |
| Descriptor | A short readable description | Supply air temp |
| Point type | AI, AO, BI, BO, or a software value (AV, BV, MSV) | AI |
| Field device | What the point reads or drives | Duct temperature sensor |
| Signal / units | Electrical signal and engineering units | 10k thermistor, °F |
| Location | Where the device is installed | AHU-1 supply duct, Mech Room 101 |
| Alarm / trend | Whether the point alarms or is trended | Alarm high/low, trend 15 min |
What are the point types?
Physical points are wired to a controller terminal. Software points live inside the controller. In BACnet terms:
| Type | Meaning | Typical use |
|---|---|---|
| AI | Analog input | Temperature, pressure, humidity sensors |
| AO | Analog output | Valve or damper actuator, VFD speed command |
| BI | Binary input | Fan status, filter alarm, freeze stat |
| BO | Binary output | Fan or pump start/stop |
| AV / BV / MSV | Analog, binary or multi-state value | Setpoints, modes, occupancy schedule |
Counting physical points by type is how you size controllers: the I/O summary tells you how many inputs and outputs of each kind every controller needs.
How do you build it from the control schematic?
Start from the control schematic. Take each component, one at a time, and ask what the sequence needs to read from it and what it needs to command. A supply fan, for example, gives a start/stop output, a status input and, with a VFD, a speed command. Repeat for every coil, damper, sensor and safety, then group the points by controller.
Name the points as you go, with one naming rule for the whole job (see BAS point naming conventions). The sequence of operations should then refer to those exact names.
Free template
The template below has the columns above and one worked example: a constant-volume air handler with mixed air dampers, a chilled water coil and a hot water coil. Replace the example with your own job.
Sources
- Siemens, guide specification Section 23 09 00 – Building Automation System (submittals, network, point naming)
- AutomatedBuildings.com, how to start a point list from the control schematic (2018)
- UConn, Appendix V – Building Automation Standards
- WBDG, UFGS 23 09 00 – Instrumentation and Control for HVAC (U.S. Department of Defense)
- BACnet International, about BACnet (ANSI/ASHRAE Standard 135)