Hi @cperez. I’m not a professional BMS engineer, so I can’t answer all of your questions. But I can relay my observation while managing our own system at headquarters in Folsom.
This really is a question of “What tool do you want to use?”. Whether to use BMS software or Ignition, or both, depends on your preferences and skill set.
What I have observed is that dedicated BMS systems require a great deal of training in the way they do things… but once you’re trained, its fairly easy to use, and everything you should need is within their “walled garden”. As far as the control logic, they usually have a bunch of premade components (purpose built for Heating and Air, Lighting, etc.) you can lay out and just connect the dots. Outside of re-arranging their pre-built components, you have no real room for custom programming. BMS systems usually have a dedicated controller, with “remote I/O” devices, which removes the need for a separate PLC (again, this is my limited knowledge). You can’t build a custom integration of your own without leaning on the original developers of the BMS software.
Lets take an example… say you had a complete BMS, and then needed to pull data from PLCs elsewhere in your plant that don’t talk BACnet… Lets say every time Line 1 is cutting hardwood, you need the BMS to reduce airflow in that area… You would have to figure out some other way to do it, external to the BMS software (but hey, that’s the job of Integrators, is it not?).
Okay so, as you know, Ignition is a platform that can tie into any source of data and show them up as tags. Now that we have recently added the BACnet driver, Ignition can be a BMS. But you’re not going to have all of the pre-made software components for controlling Variable Air Valves, Supply and Exhaust Fan PID loops, Compressors, Condensers, etc… So you will be building all of that PLC logic yourself (which you may prefer being in full control of, given your background). Additionally, the equipment associated with a BMS may require traditional BMS software to use them (such as the equipment that would actuate a VAV directly, which talks ARCnet across two wires back to a central BMS Controller). Such a BMS controller would then have an ethernet port you could connect to with Ignition’s BACnet driver.
And this is the case we are in with our headquarters. We have VAVs throughout the building, which it was easier for us to use a BMS just to control those… and have a PLC controlling the Air Handling Units on the roof (since we come from an Integrator background with decades of PLC experience), with Ignition tying the two together. Ignition passes tag values back and forth (VAVs need to know what temp the Supply air is, and the AHUs need to know the combined airflow of all VAVs to determine if its safe to turn on Compressors). To be honest, our VAV controller can be a complete BMS on its own (that company could have controlled the whole thing). But I ask you A, what’s the fun in that? and B, would you want to be at the mercy of their programmers? Or would you want all the tools in your belt?
Our decision to integrate everything with Ignition was well founded when we were able to:
- Alert us if the VAV controller crashes (yeah that happens sometimes)
- Alert us immediately if there are power outages at the office, before UPS runs out (fun trick).
- With historical charts and alarms, we were able to pinpoint the cause of our heater units failing!
- Handle issues with building pressure (exterior doors were blowing open or pulled inward, making it hard for people to come in and out) due to the spec’d exhaust fan not able to run slow enough, or fast enough, to recover from the occasional 20mph winds. We were able to put custom logic to handle this, which wouldn’t have been possible for us to implement in-house with a BMS.
- Tracking maintenance of equipment for faster debug when they fault.
- Easily lock out equipment that regularly fails, until it can be repaired.
- One of our AHUs switches between heating and cooling… having so many data points historically logged allowed us to increase occupant comfort by doing optimizations to the decision to flip modes.
- We have the ability to pull in any source of data we want, such as mounting our own Weather Station on the roof to determine the exact UV levels to determine if the sun is baking the exterior offices, to get ahead of the cooling curve. The possibilities are endless.
There is no doubt it took us longer to implement our system than it would have taken a traditional BMS solution. But personally, the flexibility we achieved beyond what a BMS can do, is INVALUABLE.
So the choice is yours, depending on your skill set and preferences.
I hope this insight helps you and others.