The disclosure provides an HVAC data processing and communication network. In an embodiment, the network includes a first zone and a second zone. The first zone has a first demand unit and a first subnet controller configured to control an operation of the first demand unit via a data bus. The second zone has a second demand unit and a second subnet controller configured to control an operation of the second demand unit via the data bus. The second subnet controller is further configured to communicate with the first subnet controller via the data bus.