What a school retrofit actually looks like

If you’ve done controls work in schools, you already know how these projects usually start. The drawings are incomplete. The MS/TP trunk “mostly works.” Teachers are in the building. And the district wants everything done with minimal disruption.

You’re not installing a brand-new system — you’re stitching a modern automation layer onto equipment that’s been modified, repaired, and repurposed for years. That reality shapes every decision you make.

Why open protocols matter more in retrofits than new builds

In this environment, flexibility matters more than perfection. BACnet, developed through ASHRAE (ANSI/ASHRAE Standard 135), allows devices from different manufacturers to communicate on the same network. For schools, this isn’t a philosophical preference but rather a practical requirement.

Districts rarely modernize everything at once. They upgrade one wing, one building, or one system at a time. Open protocols make that possible without forcing a full rip-and-replace every few years.

MS/TP: the network that causes the most callbacks

BACnet MS/TP is common in school retrofits because it’s cost-effective and familiar. It’s also responsible for more intermittent issues than almost any other part of the system.

An MS/TP trunk that’s “almost right” often works well enough to pass startup. Then, weeks later, you get the call: points dropping offline, schedules not executing, or alarms firing without a clear cause.

Independent guidance consistently points to wiring and configuration as the root causes of these problems.

See BACnet MS/TP wiring best practices and Neptronic’s MS/TP overview.

Field lessons that prevent repeat visits

• Treat MS/TP as a true daisy chain. Star wiring might “work” temporarily but often fails under load.
• Terminate only the ends of the trunk. Extra terminators in the middle create hard-to-find communication issues.
• Ground shields at a single location. Multiple grounds invite noise problems that show up intermittently.
• Lock down baud rate and addressing early. Changing them late in commissioning is a common source of confusion.

Integrating legacy equipment without overreaching

Most schools still have boilers, meters, and packaged units speaking Modbus or proprietary protocols. The temptation is to pull in every available point. That usually backfires.

Successful retrofits focus on what operators actually need: status, alarms, key setpoints, and a small number of performance indicators. Anything more increases complexity without improving outcomes.

Commissioning for the people who inherit the system

A clean startup doesn’t guarantee a successful project. What matters is how the system behaves once you’re gone.

Commissioning should prioritize clarity over completeness. If a facilities team can’t quickly understand what’s normal and what isn’t, they’ll struggle to maintain the system — and you’ll get the call back.

• Verify occupancy, warmup/cooldown, and ventilation sequences under real conditions.
• Check network stability over time, not just at a single moment.
• Leave documentation that answers real questions, not just compliance checkboxes.

Why KMC Controls

KMC Controls designs open-protocol building automation solutions with retrofit conditions in mind. Controller families such as KMC Conquest^® and tools like KMC Workbench™ support BACnet integration while giving integrators practical ways to configure, troubleshoot, and document systems.

For ventilation verification, TrueFit^® AFMS supports characterized airflow measurement, helping teams validate performance during commissioning and over time.

A practical takeaway

School retrofits reward realism. Define standards early, keep scope focused on operational value, and assume the next person will need to understand your work. That mindset reduces callbacks, builds trust with facilities teams, and makes systems supportable long after turnover.

Many thanks to Jesse Shoemaker’s expertise in editing this article. Jesse serves as the Vice President of Business Development at KMC Controls.