.Buildings.ThermalZones.EnergyPlus_9_6_0.Examples.SmallOffice.ASHRAE2006Winter

Information

This model consist of an HVAC system, a building envelope model and a model for air flow through building leakage and through open doors.

The HVAC system is a variable air volume (VAV) flow system with economizer and a heating and cooling coil in the air handler unit. There is also a reheat coil and an air damper in each of the five zone inlet branches. The figure below shows the schematic diagram of the HVAC system

See the model Buildings.Examples.VAVReheat.BaseClasses.PartialHVAC for a description of the HVAC system, and see the model Buildings.ThermalZones.EnergyPlus_9_6_0.Examples.SmallOffice.BaseClasses.Floor for a description of the building envelope.

The control is an implementation of the control sequence VAV 2A2-21232 of the Sequences of Operation for Common HVAC Systems (ASHRAE, 2006). In this control sequence, the supply fan speed is regulated based on the duct static pressure. The return fan controller tracks the supply fan air flow rate. The duct static pressure is adjusted so that at least one VAV damper is 90% open. The economizer dampers are modulated to track the setpoint for the mixed air dry bulb temperature. Priority is given to maintain a minimum outside air volume flow rate. In each zone, the VAV damper is adjusted to meet the room temperature setpoint for cooling, or fully opened during heating. The room temperature setpoint for heating is tracked by varying the water flow rate through the reheat coil. There is also a finite state machine that transitions the mode of operation of the HVAC system between the modes occupied, unoccupied off, unoccupied night set back, unoccupied warm-up and unoccupied pre-cool. In the VAV model, all air flows are computed based on the duct static pressure distribution and the performance curves of the fans. Local loop control is implemented using proportional and proportional-integral controllers, while the supervisory control is implemented using a finite state machine.

A similar model but with a different control sequence can be found in Buildings.ThermalZones.EnergyPlus_9_6_0.Examples.SmallOffice.Guideline36Winter.

References

ASHRAE. Sequences of Operation for Common HVAC Systems. ASHRAE, Atlanta, GA, 2006.

Revisions

• December 20, 2021, by Michael Wetter:
  Changed parameter declarations for issue #2829.
• October 4, 2021, by Michael Wetter:
  Refactored Buildings.Examples.VAVReheat and its base classes to separate building from HVAC model.
  This is for issue #2652.
• September 3, 2021, by Michael Wetter:
  Updated documentation.
  This is for issue #2600.
• November 25, 2019, by Milica Grahovac:
  Impementation of Buildings.Examples.VAVReheat.ASHRAE2006 model with an EnergyPlus thermal zone instance.