Hello!
I am exploring the 2 Zone Data Center model included in the EnergyPlus installation. You can see the model description here at NREL github-repository.:
The model has a thermostat with two setpoints. It is described as follows:
ZoneControl:Thermostat,
West Zone Thermostat, !- Name
West Zone, !- Zone or ZoneList Name
Zone Control Type Sched, !- Control Type Schedule Name
ThermostatSetpoint:DualSetpoint, !- Control 1 Object Type
Temperature Setpoints; !- Control 1 Name
ZoneControl:Thermostat,
East Zone Thermostat, !- Name
East Zone, !- Zone or ZoneList Name
Zone Control Type Sched, !- Control Type Schedule Name
ThermostatSetpoint:DualSetpoint, !- Control 1 Object Type
Temperature Setpoints; !- Control 1 Name
ThermostatSetpoint:DualSetpoint,
Temperature Setpoints, !- Name
Heating Setpoints, !- Heating Setpoint Temperature Schedule Name
Cooling Setpoints; !- Cooling Setpoint Temperature Schedule Name
Schedule:Compact,
Zone Control Type Sched, !- Name
Control Type, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: AllDays, !- Field 2
Until: 24:00,4; !- Field 3
Schedule:Compact,
Heating Setpoints, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: AllDays, !- Field 2
Until: 7:00,20.0, !- Field 3
Until: 17:00,20.0, !- Field 5
Until: 24:00,20.0; !- Field 7
Schedule:Compact,
Cooling Setpoints, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: AllDays, !- Field 2
Until: 7:00,23.0, !- Field 3
Until: 17:00,23.0, !- Field 5
Until: 24:00,23.0; !- Field 7
My suggestion was HVAC equipment should try to return the zone temperature to the given range, and should be below 23 degrees, but it always remains above these values.
If I change, e.g., the heating setpoint value, the difference will only be that the temperature curve decreases or rises accordingly setpoint direction change (up or down), but everything will also be above the upper limit (heating setpoint).
On the plot, you will see the same zone temperatures. This is because I changed the air flow calculation method in the second (EastZone) to AirFlowFromSystem which the same as WestZone:
ElectricEquipment:ITE:AirCooled,
EastDataCenter_Equip, !- Name
East Zone, !- Zone Name
FlowFromSystem, !- Air Flow Calculation Method
!#FIX! FlowControlWithApproachTemperatures, !- Air Flow Calculation Method
[img]https://i.imgur.com/ZYArG0A.png[/img]
I read the documentation saying (Input Output Reference, pp. 1.35.1.2.5 Zone Thermostat Heating Setpoint Temperature), but I couldn’t understand how to explain this behavior. Can someone help me?
