HVAC System Type

HVAC tab in model data


Compact HVAC systems are used when the HVAC model option is set to Compact and is a powerful entry way into EnergyPlus HVAC modelling allowing you to model HVAC systems in quite some detail without the need to draw an air flow network and deal with the complexities of control systems and node connections. You can model many common HVAC systems including VAV with terminal reheat, VAV with PIU, Constant volume, Fan coil units, Packaged DX units and Mechanical ventilation.


EnergyPlus simulations are carried out on the detailed HVAC component models generated by DesignBuilder from the compact descriptions.


When the HVAC model option is set to Compact, there are 5 HVAC system types:



  1. Only one CAV, VAV or Unitary multizone system can be defined per building.
  2. If you select Unitary multizone, CAV or VAV at zone level, then the same selection must be made at building level.
  3. You can enter Fan coil and Unitary single zone systems in any zone without concern for the selection at building level.
  4. Up to 400 zones can be modelled simultaneously using Compact HVAC systems.  It is possible to model more zones than this by making changes to the IDD file (contact DesignBuilder or EnergyPlus Support desks for more information about this).
  5. Pumps are modelled using typical default data.
  6. Unitary multizone and Fan coil units cannot be used in same building.
  7. Fan coil units are incompatible with Calculated natural ventilation.