A Zone is a group of Rooms which share common internal conditions and external adjacency. Critically, each room within a zone shall have the same temperature set points as the zone will contain a single thermostat for controlling that temperature. In load and energy modeling Zones are used to reflect the intended grouping of rooms on to Variable Air Volume (VAV) boxes, Fan Coil Units (FCU), or other terminal units which will serve the group of rooms. By running simulations with these rooms grouped, the coincident peak is reported for the zone allowing for right sizing of equipment.
If no zones are created or assigned to air systems in a project, a zone will be automatically created for each room of the model. The results will be reported per zone and run using the 'Ideal Air Loads' system within EnergyPlus.
To help organize the large amount of data that goes into the building analysis model of a project a simple data hierarchy is used to show connections between types of elements. Here are the rules that pertain to zones:
Zones can include any number of rooms
Zones can be assigned to a only one Air System at a time
Empty Zones (without any rooms assigned) cannot be assigned to Air Systems
Zones must have unique names
Rooms making up a Zone must have the same heating and cooling setpoint