You can stick with local control and no internet access, all of the major BAS integrators offer completely offline systems. A BAS system is pretty simple, there are microcontrollers with binary and analog inputs and outputs that get networked together (RS-485, Ethernet, ARCnet), sensors and relays get wired to the microcontrollers. The microcontroller network is usually connected to a control panel that orchestrates the controllers, this is what you can connect to via the internet or a local pc not attached to the internet.

But pretty much any grocery store with multiple refrigerated/freezer cases is going to have an automation system that runs it.