How do you plan to handle security (both network and employee)? Target was breached through their HVAC system (which was linked to internal networks in some places). It's suspected that a bad actor got a job at their HVAC vendor long enough to find some good vulnerabilities, and then just went to town.
Is your current implementation an inventory tagging system? Or are you connecting to these HVAC units via BACnet to get real-time data about their current state and conditions? Or, is that your plan for the future?