.Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.Economizers.Controller

Information

Multi zone VAV AHU economizer control sequence that calculates outdoor and return air damper positions based on ASHRAE Guidline 36, May 2020, Sections: 5.16.2.3,5.16.4, 5.16.5, 5.16.6, 5.16.7.

The sequence consists of three sets of subsequences.

• First set of sequences compute the damper position limits to satisfy outdoor air requirements. Different sequence will be enabled depending on the designes minimum outdoor air and economizer function, which include
  1. separate minimum outdoor air damper, with airflow measurement. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.Economizers.Subsequences.Limits.SeparateWithAFMS for a description.
  2. separate minimum outdoor air damper, with differential pressure measurement. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.Economizers.Subsequences.Limits.SeparateWithDP for a description.
  3. single common minimum outdoor air and economizer damper. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.Economizers.Subsequences.Limits.Common for a description.
• The second set of sequences which have one sequence enable or disable the economizer based on outdoor temperature and optionally enthalpy, and based on the supply fan status, freeze protection stage and zone state. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.Economizers.Subsequences.Enable for a description.
• Third set of sequences modulate the outdoor and return damper position to track the supply air temperature setpoint, subject to the limits of the damper positions that were computed in the above blocks. Different sequence will be enabled depending on the types of building pressure control system, which include
  1. relief damper or relief fan control. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.Economizers.Subsequences.Modulations.Reliefs for a description.
  2. return fan control with airflow tracking, or with direct building pressure control. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.Economizers.Subsequences.Modulations.ReturnFan for a description.

Revisions

• March 1, 2023, by Michael Wetter:
  Changed constants from 0 to 0.0 and 1 to 1.0.
  This is for #3267.
• August 1, 2020, by Jianjun Hu:
  Updated implementation according to ASHRAE G36 official release.
• October 11, 2017, by Michael Wetter:
  Corrected implementation to use control loop signal as input.
• June 28, 2017, by Milica Grahovac:
  First implementation.